Air over fire ?

[Dan W]

I have done a search and can't find this info so excuse me if it has been discussed. I am contemplating AOF but am having trouble with the size of the blower. I know it should be around 20/80 under and over but how many CFM's at what static would I need for a raised flue 2x6 with an 8 inch stack? Right now I have a blower under the fire that took me several boils to finally get the hang of adjusting the damper on the inlet(almost closed inlet-lots of CFM) and I can get about 30 GPH. But, AOF seems to be the way to go. I have the means to make it just not the technical info on the design. Also, how critical is pre heated air? I could do that too if it was essential. Is it true that oil burner blowers will work for high pressure blowers? Any input would be appreciated. Thanks, Dan.

[maple flats]

Try this: http://mapletrader.com/community/showthread.php?t=7884&highlight=added+over+fire+high+pressure

[maple flats]

Final result after very short season. I boiled faster and used 30% less wood. Not a bad combination.

[WESTVIRGINIAMAPLER]

Here is what I am putting on my 2x8. I have spent a lot of time working on it and buidling the manifold and dampers. So far, I have a lot done, but quite a bit more to do and hope to get back on it in a couple of weeks.

http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=7c447&op=search&Ntt=7c447&N=0&sst=subset

I watched ebay and bought the blower and the motor seperate for about 50% of the cost of what Grainger wants for the entire setup and the motor was new and the blower had been used less than an hour.

[maple flats]

That is the right type of blower. Mine looks similar, except it is all cast iron and about 50+ yrs old, maybe even from 75+ yrs. And it was free, did I ever mention I like free? Even I can afford that price.

[jimsudz]

Dan,I built a new arch this past winter for my new lapierre 2.5x8 raised flew pans.The arch is air tight I built it so I get most of the air under fire but i also have air ducted mid way up the arch in front and at the top shooting forward before the flew pan trying to get the flames to roll under front pans.I used a furnace blower that has 4 spds, I have to run the blower on low and have to restrict blower intake, because I don't have hoods and the sap will jump right out of back pan. Another problem is I'm shooting dime size embers 30 ft in air kinda dangerous in dry wheather. I couldn't get it dialed in last season beacause I didn't get my new pans till 2 weak into season.Iwas able to boil aprox.75 gal with out pre heater.This season I will have hoods,preheater, and the right wood so I will be able to get blower adjusted and be able to calculate wood consumtion to see how efficient it really is.My biggest concern is the embers, does any one have sugestion.

[woodshillmaple]

Do you have a spark arrestor at the base of the stack? It is basically a wire mesh screen with maybe 1/4" spacing fit over the back of the arch where the stack fits on.

[WESTVIRGINIAMAPLER]

I think this is one of the advantages 80% air over top of the fire and 20% air under the fire. All the air under the fire is blowing the embers out of the stack as it sounds you have it reversed. I would think if the majority of the air is above the fire, you wouldn't see any sparks. I know nothing about this subject, but hopefully intend to find out in a few months.

[TF Maple]

Do you have a spark arrestor at the base of the stack? It is basically a wire mesh screen with maybe 1/4" spacing fit over the back of the arch where the stack fits on.

A spark arrestor is good but you have to make sure the screen doesn't plug up and restrict air flow.

[maple flats]

I have no spark arrester. One is not needed. Everything burns up under the pans with the turbulance you get with the high pressure air blowing down at a 10 degree angle. If you do it with high volumn low pressure air I do not know. When this is in operation you have faster boils, lower stack (yes lower) temps and no sparks or flame at the top of the stack. Your complete burn takes place under the pans where you can use it. That is why you will save wood. The efficiency climbs. I do not need to shut the blower off to fuel either, even with both doors open and the blower going the natural raft keeps everything flowing up the stack and away from the door. Before using mine I thought I would need to shut down to refuel and did initially but later found it not necessary. I don't even slow the air to add wood. The only regulation of air is to start and at the very end of the burn. To start the air is low and mostly under the fire, when it gets going good I change to my boil setting which is about 70-80% over and 20-30% under. On shutdown it goes back to start up settings.

[Gary R]

Mine also has most of the air over the fire. When its running, you wouldn't even know a fire is going by looking at the stack. Hardly any smoke. I need to shut my blower down to fuel. My manifold is not large enough and I plumbed the air over into the back center of the manifold. This causes most of the air to be blown right at the door. I would now plumb air to both sides of the manifokd entering at the back of where the manifold goes front to back.

[WESTVIRGINIAMAPLER]

Finally was able to get the manifold in place and got the dampers in place and welded up today also. I spent a lot of time working on it in May and other than a couple of hours this past Monday which I had off for the fourth, I haven't been able to work on it for about 6 weeks. Very happy so far with how it turned out and have everything in place except the final stage of the damper controls which shouldn't take but 2 or 3 hours to finish. One of my top rails had about 1/2" sag in the center of it, so I replaced both of the top rails with a heavier gauge and slightly bigger rail.

I have a new high pressure Dayton blower and still need to get a 6" PVC line and run it from the woodshed to the evaporator which is about 20' away plus about three 90 degree turns on the pipe to get it down and in the right place. Hopefully I can have everything in place by September and give it a test fire.

32 nozzles that are 3/8" injecting air on all four sides of the fire. 23 on the Manifold and 9 around the arch front with 8 on each side of the fire above the fire and 7 behind and above. The 8 on each side are 4" apart and they alternate every 2" from side to side to hopefully get more of a swirling effect. 4 of the nozzles behind the fire blow straight forward and the other 3 are angled down 10 degrees along with all 16 on the sides are angled down 10 degrees. It has been a lot of work and time partly because I don't have the best tools for the job, but I managed to get it done with a lot of help from one of my syrup helpers that is retired and has a welder and has been a great help.

Don't expect to gain a whole lot other than efficiency, but we'll see. Plan on pouring a castable refractory cement grate for the evaporator also designed exactly the way it is recommended by Univ of VT.

Good thing I didn't know how many hours it was going to take for everything or I may have backed out before I started. LOL. Biggest thing is planning and thinking everything thru. I probably have changed things 100 times due to thinking up a new idea. Either way, sure hope it is worth all the time and effort. Hope to find out a little better how it performs in a couple of months.

I will get a fews pics posted on my photobucket link in my signature sometime tomorrow.

[maple flats]

I have no idea what the CFM's are on mine but it sure does a good job and seems to produce what the research papers say I should get. My guess is mine is close to the needed CFM suggested in the report for a 3x8. Refer to the link in reply # 2

[WESTVIRGINIAMAPLER]

Here's the link to the pictures for the air injection:

http://s203.photobucket.com/albums/aa160/wvmapler/Air%20Injection/

[brookledge]

Brandon
You will definately have to tell us the difference it makes for you
Keith

[WESTVIRGINIAMAPLER]

The air injection system is about complete. I need a couple more hours to hook up the blower and get it in place and run a few more feet of 6" PVC. I am running about 38' of 6" pvc to get the air into the evaporator. I poured a grate last week out of Rutland castable refractory cement very close to the description in the VT research paper. As they suggest, I used ice cream sugar cones and they do make a nice hole in the grate. I have 27 holes in my grate which is 19" W x 25" L. The holes start 7" from the arch front and end 3" from the rear of the grate. I have the rows of holes alternating with 5 holes in first row and 4 in second row and they alternate like this every other row. The spacing of the holes on each row alternates every row to try to maximize efficiency. I poured the grate about 3.25" thick and it has 5 pieces of 1/2" rebar squeezed in it between the rows of holes and about the middle of the thickness and the rebar is all running lengthwise with one one each outside and 3 in the middle. This was not recommended but I felt over time, this would ensure the grate if it developed any cracks. I spoke with Rutland and they agreed this could do nothing but help. Need to let the grate dry another 25 days before doing a test fire. I needed to boil out the evaporator as I intentionally didn't clean it at the end of last season so I could do it when I do a small test boil. This project has kicked my butt at times and I can't imagine how many hours I have in it, but I have tried to do it right with nor shortcuts. Don't expect to damper the over fire air much if any but I do have a damper control for it and a separate control for the under fire air which will be most needed for controlling air under fire.

I have come up with other things like the rebar that I think will work better in the long run. For instance, the ice cream cones were wrapped with packaging tape completely on the outside before the concrete was poured. I waited until the next day to pull them out and I was able to pull them all out in one piece since they had tape on them or I would have spent a good while digging out the pieces of them if they hadn't been wrapped. I am not sure how many hours I have into it, but it is a lot and I have several times the amount of hours into the project that I have in thinking things out and coming up with ideas.

[user587]

Thanks all for the great info. One question - I see the pics with the 2" sq. tube manifold. Will this be covered/buried in brick, or will it (or part of it) remain exposed to the comb. chamber? Does all steel on the inside of the arch need to be "covered" by bricks?

I'm thinking of making an arch approx. 2x6, and it seems best to build in air (over and under fire) from the beginning. My initial thought is to make the arch frame upper horizontal long rails be made from sq. tube instead of angle, and then there is a built-in manifold for air injection, I could add outlets in the comb. chamber area only. Any advice from the pros pro/con?

Thanks to the regulars for all of your posts - I've learned a lot from perusing, and I'm thankful for it.

[Sugarmaker]

Brandon,
I chuckled (kind of) when I read your posts about the amount of time you have put into your AOF and grate system. (sounded like my last maple project). I am sure it will be well worth it! There is satisfaction in doing and learning along the way. I think your work looks very well thought out and the design and fab work looks clean. A nice project that should net you some good rewards in fuel savings.
I will be watching, as I may need a project for next season on the old 3 x 10:) Now that I have a MIG welder it may not be that far out of reach. I don't have a air tight front though.:(

Do you have the specs on the Dayton blower you used? (I need one more blower running while making syrup.:))

Regards,
Chris

[WESTVIRGINIAMAPLER]

Here's the blower with specs.
http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=7c447&op=search&Ntt=7c447&N=0&sst=subset

[WESTVIRGINIAMAPLER]

Thanks all for the great info. One question - I see the pics with the 2" sq. tube manifold. Will this be covered/buried in brick, or will it (or part of it) remain exposed to the comb. chamber? Does all steel on the inside of the arch need to be "covered" by bricks?

I'm thinking of making an arch approx. 2x6, and it seems best to build in air (over and under fire) from the beginning. My initial thought is to make the arch frame upper horizontal long rails be made from sq. tube instead of angle, and then there is a built-in manifold for air injection, I could add outlets in the comb. chamber area only. Any advice from the pros pro/con?

Thanks to the regulars for all of your posts - I've learned a lot from perusing, and I'm thankful for it.

Yes, above the manifold to the rails is firebrick and the manifold itself is covered with castable refractory cement. I started to go with ceramic blanket but since I needed four 25 lb buckets of refractory cement for the grate, I ordered an extra bucket and cast it all over with refractory cement. I will have some newer pics posted soon.

As far as building an arch, I think the best thing would be to incorporate it into the arch when you build it. I am learning to weld too with a mig welder and amazing how easy it is. As far as using the square tubing as the top rail, good idea but not sure how it would stand up to heat unless it was protected. You could firebrick up to the bottom and cover the side with castable refractory cement or ceramic blanket.

[Sugarmaker]

Brandon,
Sorry I didnt see the graniger link in previous comments. Thanks, Thats one large unit of a blower! Make sure up have your self strapped to something when you open the door to fire:)
I think we should start a contest to see who has the most and least bells whistles, switches and valves to get one of these going.:) Probably Theron:)
Regards,
CHris

[maple flats]

If your over air works like mine, you will get nothing out the door when you open it to add wood, except the heat from the inferno within. I do not shut down or slow the blower to fuel. I get a slight suction into the arch but it is very slight. It will not suck your wiskers off (nor your hat).

[maple flats]

You are adding medium volume high pressure air and the draft on the stack is taking it all and slightly more when the feed door is opened.

[nymapleguy607]

Not to change the subject but would a blower off a dust collector work? After looking at some of them they have a paddle type impeller blade I thought this might be a cheaper way to upgrade

[maple flats]

Do they have a series of paddles that "throw" the air out, or are they just swirls that "fling" the air out by centrifical force? If they are actually paddles they just might work.
The paddles in mine are cast iron and they do not fit close tolerance inside the housing but the fan sure does put out good pressure. I do not have a reading yet. I might sometime install a gauge (which I also got from the closed out factory) but I haven't yet. I'm not even sure where to install the gauge. The air goes out several nozzles over the fire and through a bunch of 1/4" drilled holes in a 4" stove pipe laid under the grates.

[WESTVIRGINIAMAPLER]

I did get it all hooked up working a few hours on it Wed and yesterday and it seems fine. It took about 37' of 6" PVC to run it from outside to back of the evaporator with 3 elbows. I took several pictures but forgot the camera card at home as I am in VA with my wife in the hospital as she had sugery this morning. I ran the blower on 110 instead of 220 as the motor can be wired either way and it is turned on with a 20 amp breaker which is only a few feet from the evaporator. Dampers seemed to work good but unable to see exactly how it is going to work as I don't have any grate in the evaporator yet as the castable grate is still home in the garage drying. I took form off a couple of days after I poured it to help it dry good. They told me to let the grate dry 30 days for best results, so I will try to fire it up in about 3 weeks to clean the evaporator pans as they are still dirty intentionally so I would have an excuse to fire it up. I have all the pipe joints and adapters screwed together, not glued in event I need to take something apart. I also have all the joints and any possible air leak locations sealed good with aluminum HVAC tape.

I have tried to do it right and not take any shortcuts, just improvements so it will be interesting to see how it works. The above fire nozzles really jet out the air when the lower damper is nearly closed.

I did buy the blower and motor seperate on ebay and have about 50% or less in them than the grainger price. Motor is brand new and blower was used about 45 minutes for a demonstration.

[Brent]

This is a topic that I had a lot of fun with last year. My rig is a Phanuef 2x6 raised flue. After reading the studies done by Proctor and Michigan, that basically said the same thing, I put two very small blowers on in the '09 season. I like what they did but it was not dramatic. For the '10 season I put two stainless steel tubes all the way from the back, under the insulation, (raised flue) and into the fire box. I got a "high pressure blower" that put out nearly one PSI, started drilling holes in the stainless with very tiny holes and lit the fire. The result felt good so I drilled the holes out bigger and bigger. By the standards of some of the pictures my holes were tiny. I don't think the biggest got to 1/8" - but I had lots of them. There was about 3" of pipe exposed and I put the holes about 2" apart = 18 x 2 tubes = 36 of them. The blower was about 3/4 Hp. No rehostat. The draft door was left open about 1/2". The arch was not modified in any other way ... certainly not airtight. I could fire it with the blower running. Firing intervals went from typical 5 - 7 minutes to 20 minutes and the stack temp stayed above 1000 degrees. Towards the end of the season I was firing about every 12 minutes and holding the stack near 1100 pretty steady. Roughly, my wood consumption was cut ing half.

If you want to boil fast, then I think higher volumes of air will do the trick, at the expense of more wood, and I think air over or under the fire will work ... enough volume that you need an airtight arch and a switch or rehostat to set the blower lower when firing.

If you want efficiency, I think the emphasis is on small high pressure, high velocity air almost all over the fire.

This coming season I'll be firing up a new-to-me 2-1/2 x 8 with an Inferno arch. I plan to leave the Leader blower
system intact but add two pipes on each side of the firebox to blow down at about 30 degrees into the wood. I have picked up a GAST Regenair blower that puts out about 3 1/2 the pressure of the squirrel cage blowers that Leader put in the Inferno and mentioned by WestvirginiaMapler. The spec on the GAST is 28"WC. I think the higher pressure will cause more turbulence and better oxygen mixing, without blowing unburned wood gasses up the stack.

And hopefully without many sparks. Last year we had near zero sparks fly out.

It's going to be an interesting season.

[whalems]

I am getting ready to rebuild a 4' vermont arch and was thinking of adding air over. My question is should i put air tubes in the back of the fire box if I dont have an air tight door? I could see it making a real mess. Or is it better to have it there and just have some of the ash blow out the door? I have never used a "real" evaporator so some of this will be trial and error I am sure:lol: Any suggestions are most welcome.

[WESTVIRGINIAMAPLER]

Know nothing about the subject, but I would think that if you have air behind the fire and both sides of the fire, the air from both sides would help cancel out the rear air blowing out the front of the arch. My rear air is 36" from my arch front, not nearly as far as it would be on one of the new nigh efficiency arches, but I am not concerned with it blowing ash out the front as I have 7 nozzles behind the fire and 8 on each side of the fire. I also have 9 more around the arch front in front of the fire, so they should give it some turbulence. I used 1/4" steel pipe for the air behind and on both sides of the fire because it is almost 3/8" ID whereas 3/8" pipe is right at 1/2" id. I added the nozzles every 4" on the sides and the air behind the fire is every 3". The side nozzles are pointed down aprox 10 degrees and four of the rear nozzles are pointing straight forward and 3 are pointed down aprox 10 degrees and they alternate to try to get best air mixing and swirling action of air.

[Brent]

Whalems

I think this thread could be split into two.
Those that have lots of wood and primarily want to increase the boil rate, and those that are primarily trying to economize on wood.

If your goal is to boil harder, then lots of air, up to the point you create pressure in the arch and would blow ash out if it wasn't air tight, is the way to go. The Dayton style (furnace style) blowers will give you lots of volume. These are not high pressure in my mind, even though the ads say they are. You'll need to control ash at both ends, ie around the arch and coming out the stack in the form of sparks. Your stack temps will go way up. You may need to add a heat shield between the stack and the flue pan or you could get scorching of splash on the back wall of the flue pan. The guys I got my Leader with the Iferno arch had this problem. A simple sheet of stainless standing between them was all it took.

If your goal is to maximize efficiency, you want a lower volume high pressure blower. Your stack temps won't change much, at least mine didn't, but your firing fequency will get longer and you could cut your wood consumption in half, maybe more because I'm sure what I did can be improved upon. I used lots of small holes. I could see the yellow/blue swirls from the injected air about 6 - 8 inches into the fire. Given that the pipes were only 18-20" apart, I think the fresh air was getting to most of the fire. When the blower came on there was a rumbling sound to the fire.

I see from your signature that your arch is 4' wide. I think the newest hi performance arches that wide have air nozzles across the slope, pointing back into the fire and if my arch was that big, I'd put a pipe there. How big and with how many holes depends on your goal.

One thing I would add. The first year I tried this idea, I got what I thought was good pipe from a fireplace dealer. The pipe was actually for gas furnaces/fireplaces from the spare parts list. At the end of one season it was a corroded mess. If you're going to leave the pipe exposed, go stainless. The stainless tubes I put in last year are now a little discolored, but otherwise like new.

I would also mount the tubes lower if I could to get more space between the bottom of the pans and the top of the tubes. And I make the pattern of the holes different so some sprayed air downward at say 65-70 degrees, right at the wood, and some at 45 degrees, and some at about 20 degrees, the goal being to get oxygen to as much of the flame as possible.

Good luck

[maple flats]

I have lots of wood and also have high pressure air over the fire. Just because I have lots of wood does not mean I want to burn it all up so I can cut lots more. Both wood use and boil rate were very important to me. In another thread you can read about mine, so here I will only say, I used the Proctor design and boiled faster with about 30-35% wood savings. I will get better figures this year, my season last year was way too short so I did not get to boil long enough to get a true accurate measure of iether, just approximates. Next season I will have vacuum on most of my bush so my production should rise dramatically and then I can get more precise performance figures.
At any rate, I highly encourage anyone burning wood to add some form of over fire air. High pressure is by far the best, but a squirrel cage will be better than nothing and when you make more syrup you can better afford to buy the expensie high pressure blower to gain even more efficiency and increase production at the same time. The thing about over fire air is that you burn the wood gases more completely instead of sending them up the stack. If you add just forced draft under the fire, you increase the boil rate but do not improve the combustion efficiency. I use about (guessing) 75% over fire and 25% under, might even be 80 over and 20 under. Without flow meters on each it is just a guess, but I do know one thing about it, WOW what an improvement over naturally aspirated draft. My top manifold has nozzles every 6" and they are pointed down (10 degrees if memory serves me) and I can refuel without stopping or slowing the blower with now ashes coming out the front and no sparks out the stack. The turbulance is impressive to look at.

[whalems]

Thanks for the replys. I am picking up the steel tomorrow to start the rebuild on the arch and I am sure I will have many more questions on the air over before it is all said and done:) What size tube for the manifold is recomended for a 4' arch? and what diameter holes should be used? Thanks again, Mike

[WESTVIRGINIAMAPLER]

Here is link to research project by Proctor:

http://www.uvm.edu/~pmrc/

It is under right side listed under recent publications: Guidelines for the Improvement of Combustion Efficiency for Maple Producers

[WESTVIRGINIAMAPLER]

It is showing 4" for a 4' arch and there is a lot of additional info in the paper to help you.

[whalems]

Thanks Brandon. Just read the article. very well written and easy to understand. Thanks again Mike

[Brent]

I just looked at the initial recommendations and I think anyone considering the Cornell recommendations should look at a regenerative style blower. The Dayton high pressure blowers are really furnace fans on steroids, getting specs like 8 to 10" WC. The regenerative blowers get into the range of 30 to 50" WC.

I got one from eBay about a month before I made the deal for the new evaporator. It's 2 1/2" wide and by pure serendity, has exactly the output suggested in the Cornell papaer. :D

My observations, not my science, lead me to think that more nozzels with smaller holes, will distribute the air better in the firebox and result in more complete combustion of the wood gasses. The way I did it last year started with holes about 1/32" every two inches. It was good, but every time I drilled the holes a bit bigger, the performance seemed to get better. I openned up every other hole each time I progressed. I don't know where the optimum hole diameter is but my instinct tells me that its way below the 3/8 nozzles mentioned in the article. The advantage I had with the stainless tubes was that they were totally exposed and with the pans off I could easily rotate them and drill them out. The disadvantage was that openning a stainless hole to a size larger is harder on the drill bits than drill the hole in the first place ... I should have bought stocks in a drill bit maker before I started. I thing I averaged only 3 holes per bit - even going very slow and with coolant drizzled on.

This year I'll start with the same holes I ended lastyear with, and alter the angles of injection and see how it goes.

[maple flats]

Refer to the link in reply 2 in this post and when you get there click on the link in the 1st post. That will give you the complete specifications for any size rig. Basically they say you should have a 1.5 HP high pressure blower for 4' wide rigs with a 4' square manifold around the firebox to distribute the air. The nozzles should be of 3/8" iron pipe and with a 4' wide rig you should have 2 rows of nozzles, spaced every 6" and angled down 10 degrees, maybe even stagered for the nozzles.
However, my rig is 3' wide but I used what I had for the manifold. As such I have 2" sq tube for the manifold with nozzles every 6", it works very well.

[twofer]

How are you guys hooking the square tubing up to the blower? More specifically what are you using to transition to the blower?

The reason I ask is because I'm planning on running a Dayton 7d747, per the article recommendations, and it has an outlet of 3"x3". My setup will have one 2" pipe going to the manifold above the fire and one 2" pipe into the ash pit. This means I have to figure out how to transition from 3"x3" at the blower to 2"x4" (two - 2" square tube) at the evaporator.

[WESTVIRGINIAMAPLER]

Brent,

Does Cornell have a paper on this or just Proctor?? I had not seen a paper on Cornell's website about it, but never really been on there and looked around much??

Ultimately, we are not trying to blow the evaporator apart or are we?? I would think there is a limit of enough being enough as far as pressure?? I have a big 1 HP motor turning the blower I have, so I would think ultimately your pressure is going to be based a lot on the motor you have running the blower?

[WESTVIRGINIAMAPLER]

I added some finished pics to my weblink below. Forgot to take some pics of finished damper controls and will get a couple of the grate I built out of castable refractory too in a couple of weeks.

http://s203.photobucket.com/albums/aa160/wvmapler/Air%20Injection/

Nice thing is photobucket is extremely fast now.

[Brent]

That mention of Cornell may have been a SNAFU on my part. I meant Proctor. Sorry

[Brent]

I just read some of the PROCTOR paper and wish they had
dated it.

The second thing is that they suggest 6" spacing of the nozzles, with no explanation or indication that they had tried different spacing. Given that they put the tubes behind the bricking with nozzles coming through the brick, it would have been on hell of a lot of work to make up various piping systems at say 2", 4" 6" 8" and 10" spacing to see what really worked best, rebrickinging between each configuration. Not saying they didn't do it, but it seems unlikely.

They finish the section on wood arches by saying the efficiency can be increased 25 to 50%. This makes me feel like I had beginners luck. I documented every 5 minutes of stack temps and every time I fired last year and I'm pretty confident saying that I hit 50% less wood consumption than the previous year, while maintaining the same stack temps. I'm also pretty sure that I did not luck on the optimum configuration. As I said before, every time I drilled the holes a bit larger, it got better. I never found the point that I openned up the holes an got no improvement. And while I started with holes at 4" spacing, I could see looking in the door that the areas between the injected air, were not burning the same as the areas right where the air was injected, so I doubled up and made the spacing 2" and that made a big difference. Maybe 1" is optimum .... who knows ?

Burying the tubing in the bricks makes experimenting a huge chore. The open tubes down both sides let me fiddle pretty easy.

That rig is sold to a Trader in PA and I think he'll do some of his own playing with it.

Meanwhile for this year I'm scratching my head on what to do with the Leader Inferno, that the previous owners had modified to put in more nozzles than Leader started with. It's gonna be fun.

[Brokermike]

wv mapler.

I noticed on your airtight front you have no ash pan access, is this normal?

Does the blower prevent all ash from building up?

Do you have forced air grates or are you blowing from under or behind the orginal grates?

[WESTVIRGINIAMAPLER]

The airtight arches don't have an ash pan as there is hardly any ash that falls thru as it is all burned up or blown out the top. Hopefully with the air injecting above the fire, I will eliminate most of it blowing out and all the sparks eliminated.

As far as grates, I was using fire bricks with 3 holes that were 3/4" in diameter drilled in each brick but this year I poured a grate out of castable refractory cement with 27 holes in it that taper from aprox 1.5" on air side to 3/8" on fire side for air injection. 3 or 4 or of the holes need touched up with a drill and I will put pics of it on my weblink in a couple of weeks.

[Brent]

Wow ... so that's the rest of the story.

If I get my air over fire going as I expect, on the Leader Inferno, I will have some ash falling through the grate.

I guess that means the cleanout will only be the next morning when everything is cool.

Edit # 392 of plan of action.

[WESTVIRGINIAMAPLER]

Brent,

Do you have standard wood grates in the evaporator or special forced air grates?? If it is an inferno arch, it should have forced air grates unless it is a converted inferno??

If not, you can make them with either of the two designs I mentioned earlier for a lot cheaper than the evaporator companies want for them.

I have about $ 125 in cement in the castable refractory cement. I could have probably done it a little cheaper but went with Rutland Castable refractory cement and had it shipped to their closest dealer to me as they sell it in 12.5 and 25 lb buckets and I used about 3.5 buckets(25 lb) in my grate. FYI, it was $ 36 @ bucket. Firebrick grates I already had would have probably done good too, but decided when I started this project, if I was going to do it, I was going to do it right and not take shortcuts.

All the Rutland products I have used in the past seemed to be extremely high quality and they have excellent customer support like Leader, maybe it is a Rutland VT thing! LOL. Thus the reason I went with Rutland.

[Brent]

Brandon
I this rig was made as an Inferno airtight original by Leader.
The grates are inverted V shapes with holes about 3/8 or 1/2". They look the same as thsoe in Leader's catalog on the "forced air draft units". Each section must weigh 40 lb. It has the Dayton blower under the arch and about 5" diameter heavy pipe (with lots of holes in it) running under the grates. The front looks just like the current Leader catalog. No ash door. There is an ash door at the base of the stack but Lee Porter told me he never used it. I guess they ran the fan so hard it blew all the ash out the stack. He siad they regularly got 3 to 3 1/2 GPH of syrup out, without an RO and that the Steamaway dumps 100 GPH of condensate. I suspect they used and ungodly amount of wood. I don't have that luxury.

[WESTVIRGINIAMAPLER]

Your grates would probably be sufficient and work good if you added high pressure air over top of the fire. I have one blower supplying all my air as it is more than enough and I have the above air and below air controlled by 2 separate dampers. Doubt I will be dampering the above fire air very little if any, but the under air will definitely need dampered..

[Brent]

Brandon
That sounds almost exaclty what I expect. Let it rip on the over the fire system and use the rehostat or flapper valve to limit the through the grates air.

Last year I found natural draft under the fire was plenty to give me 1100 on the stack. I don't want more than that.
Too much waste heat.

The guys on oil burners only want 800- 900.
I just read the Intensofire manual and they say 850 on the stack for wood firing.

[twofer]

When I went to the D&G open house earlier this spring they had a combustion expert giving a talk about high efficiency arches and I asked him what the optimal temperature for the stack was for peak efficiency and he said that you wanted it to be at 600 degrees. Obviously that low you are going to sacrifice some evaporation but if you're in a small run it might be worthwhile to run it that low in order to save wood and spend a little more time boiling.

On a side note I have a wood gasification boiler (solid wood, not pellets) that we heat our home with that operates at a pretty high efficiency. At peak combustion the temperature 18" above the boiler is only 300-350 degrees in the stack, even after achieving 2000 degrees+ in the secondary combustion chamber. Granted we are trying to actually boil water so it is a bit different situation but IMO this makes his recommendation of 600 degrees make sense to me.

[WESTVIRGINIAMAPLER]

This has been a very interesting and enlightening discussion and has stayed on topic and everyone has been very kosher.

[Sugarmaker]

I like the idea of 600 degree stack temp. Ours usually runs about 750+.

Brandon, is that 3 inch tubing or 2 inch? Stainless correct? and what is the wall thickness? Also what is the outside dia of the nozzles?
Thanks for sharing the pictures and information. Great project! I like the 6 inch ducting to the back of the arch. Very clean well thought out system!

Regards,
Chris

[WESTVIRGINIAMAPLER]

Chris,

The tubing is 2" square tubing with 1/4" wall thickness, so I don't think it will every burn out. The pipe is 1/4" steel pipe with ID of almost 3/8". Makes no sense that 1/4" is right at 3/8" ID and 3/8" pipe is right at 1/2" ID. Not stainless tubing, just plain old steel. Didn't really see a need for stainless as it is protected on all sides from the fire and will be air cooled.

[whalems]

I was looking at the recommended blower for a 4' arch in the grainger site and noticed it was only offered in 3 phase. If I am understanding the process correctely it is high pressure not high volume that is important, right? Is there another resource for high pressure blowers that are not 3 phase That will deliver the pressure necessary for a 4' arch?

[Brent]

Whalems
Leader puts a nearly identical single phase Dayton blower in their Inferno arches. I just got (a used) Inferno and the motor is definitely single phase. Look around the Grainger pages and I think you'll find it.

See http://www.gastmfg.com/productinfo.html

I just took a look at the GAST page and some of theirs go up to 125" WC.
I can also recommend thier dry vane vacuum pumps. I ran one last year and will run 2 on an expanded system this year. Other Traders (Haynes being one) use these pumps to.

There you will see their regenerative blowers that produce 3 to 4 times the pressure of the Dayton blowers from Grainger. I have a 3/4 Hp 110-220/1/60 that I got of eBay for $199.99. Most of the listing on eBay for these are from commercial re-sellers on the Buy-it-Now program but if you watch for a while someone will put one up like the one I got.

I think this 3/4 Hp unit will give me lots of air at the pressure suggested (30" WC) and that the under fire air will be run at very slow speed, maybe with a dump valve partially open, or maybe not at all.

Edit
the GAST I have is the R4110-2 1 Hp 110-220/1/60 and has a max pressure of 52"WC and will deliver about 60 CFM at 30"WC. I think this will do a great job ... but I only think that. First firing of the new arch is at least a month away.

[Sugarmaker]

Brandon and Brent thanks for the info. Lots of data here. Now to set and ponder a bit:) I did pull the front pan off tonight and did some eyeballing of the AOF concepts used here.

Regards,
Chris

[maple flats]

Just run off the one blower with a valve for over and under. I have a 4" blowing HP air to a y then it splits into 2- 3" lines with a valve on each to balance the flow. On mine I generally have the over air at about 60-70% open and the under air valve at about 30% open. This would not translate to 2x air over because the more a valve opens the greater the flow exponentially. I'm guessing I likely get about 80-90% over and the bal under, actual CFM. The main thing is that it is high pressure, not high volume.

[WESTVIRGINIAMAPLER]

Brandon and Brent thanks for the info. Lots of data here. Now to set and ponder a bit:) I did pull the front pan off tonight and did some eyeballing of the AOF concepts used here.

Regards,
Chris

Chris,

Take a break and go hunting with the boys for a couple of months. You need some time off. Let the rest of us scape goats work out the problem so you will know exactly what you need to do next year. That way you can spend the rest of the 4 months left until tapping getting all the bugs worked out on your evaporation enhancement!

[Brent]

I was just planning my tubing for the air injection and thought I'd better check the port size on the GAST Regenair.

I'ts only 1 1/2" Cool, I'll stick with the same size pipe I had last year.

Then I started thinking about the big furnace style blowers.
How much head do you suppose it takes to warm up all those CFM's from the cold temps near the floor or outside to the 1000 degrees plus it takes to start combustion? I havn't checked the output from the GAST but I'll bet its warmed up some just because its getting compressed. In the case of the size I've got, to almost 10 times the pressure of the Dayton blowers. When I really read the specs it hits 58" WC.

[Brokermike]

Does anyone have any thought about using black steel pipe? It is readily available and for those of us without the$ for stainless seems like a good alternative?

I'm talking about the thick wall stuff they use to run gas lines

[Brent]

The first year I tried 2 peices of steel pipe it corroded so badly that I could not get it back out the holes that I had inserted it through. It will work and gas pipe with heavy walls will last longer. The tubes I tried, (not pipe) would have perforated in the second year.

If you bury them behind the brick, they'll last a long time, but your up the creek if you want to change anything. This is still pretty experimental.

[maple flats]

This is far from experimental unless you mean your set up. I installed mine by removing the top 2 rows of firebrick, installed the manifold and exited thru the rear slope. After installing the manifold (with 3/8" pipe nozzles every 6" angled down 10 degrees) I covered them with refractory cement so only the nozzles stick out. My original intent was to cut any nozzle excess off but I never got to it. After the season I could not see any degrading of the black pipe nozzles, which stick out from 1/2" to 1.25 ". I now plan to leave them alone. I decided that with cold air blowing out thru the nozles all the time they never got hot enough to have any erosion. The refractory I put over the manifold is about 1" thick in the thinner spots, and I applied it in 2 or 3 coats with minimal firing between applications. Before adding a new layer I just brushed the surface to remove any soot. To fire it I did not burn wood, but rather I used a 500,000 BTU propane torch head with the heat turned down considerably.I am not going to try removing the manifold, it is permanently installed. If you try it without covering the tubing with some protectant, it will likely need to be replaced yearly. Things get extremely hot with over fire high pressure air.

[Brent]

Dave
There is nothing experimental about the concept. We're all pretty much agreed that air over is better. The devil is in the details. How much air, what pressure, where to aim it, how many nozzles for each width of arch, etc are all pretty much guesses until someone really gets into it. The new arch that was all the rage last year has pretty much had to recall and rebuild them all ... or so the rumors have it.

On the heating of tubes and corrosion issue. Your's are well protected and with 3/8" nozzles you will have a lot of air going through them and that will keep them cooler so you should have minimal corrosion.

Maybe someone can get an environmental grant to make real study that can answer some question to help us optimize on a good idea.

As if making good syrup consistently wasn't already complicated enough !

[maple flats]

Just follow the details in here.
http://www.uvm.edu/~pmrc/Combustion.pdf
Experimentation done!

[Brent]

They got results, you got results and I got reuslts and the system I used was miles from theirs or yours. We have no idea what the ideal system is until someone does an exhaustive study. Maybe there should be 3 or 4 rows of pipes on each side of the fire box. Maybe each should gently waft air in. Maybe we should put pipes right in the middle of the flames. I don't think anyone knows or will know for quite a while.

What we can say with some certainty is that it sure beats blowing all the air in your sugar shack up through the grates every 15 seconds. I'll have lots of pressure and the opportunity to play with a few and then more holes and blow the air in different directions. The big challenge will be to somehow measure the effect. I know my car has an oxygen sensor in the exhaust to help efficiency. I wonder if we could put one in the flue gas. I'd also like to find a digital thermometer that will stand the heat in the firebox of just in front of the flues and one at the back of the flues and derive how much heat the flues absorb with different volumes of air injected.

Going to be lot of fun. Might even make some syrup.

[Sugarmaker]

Dave and Brent and Brandon and others interested in this AOF subject,

I am kind of like Brent. A design to me is a stepping stone to saying what if I changed this what would it do then.
I think Dave and Brandon followed the suggested guidelines and will have execelent results. Keep in mind that the Thunderbolt system was developed and marketed by one company. I am sure it works. I am glad they shared the paper and information with us.
Me on the other hand will probably do something to see if a differrent AOF concept will work also.


When I saw Brents exposed pipes that allowed him to rotate the air jets I thought now thats cool. Does the system need that? Probably not, will he learn something Yes Did he share Yes!.
Pardon me for being a borderline engineer and have a strong desire to turn ideas into maybe better ideas in my garage. The maple production hobby lets us dabble with things the may help us boil water faster.

Chris

[WESTVIRGINIAMAPLER]

I am with Dave, I tried to do mine right and by the research paper even though I made several changes, it is basically permenantly mounted and protected on all sides. As I mentioned before, on the sides, I have nozzles every four inches and they are alternated from side to side 2" so they are now blowing at each other to hopefully be able to cover the fire even more. Be interesting to see what happens come spring.

[maple flats]

Sorry to be the one who is satisfied. I guess I can see the point of those who are still not satisfied that this system is the best it can be. That is what drives even more improvements in the world.
I for one put far too much on my "to do list" to ever complete it, and if I ever get close to completing it I take a little time to find more things to add. As such I do not have the time to make change after change for testing purposes. This does not mean I never try new ideas on my own, but I use others developements in things like maple where there are so many who use different approaches. MY improvements that I try are in areas where I see no one else working on my problem. However, I am glad there are those who do, otherwise I would have to add that to my to do list and I'd be even farther behind than I am.

[Gary R]

I'm with Dave on this one. The research was done by UVM and great improvements were found. Following their guidlines it burns clean and stack temps are low. I added it to mine. It helps alot. Could it be better, maybe, but I doubt any of us have the tools needed to measure any improvements we might get over UVM's. Heck just the weather from day to day changes the way things burn. As advanced as these are getting, "I think it's better", probably won't cut it. Were going to need some numbers. All this just to boil some water:D

Chris, I got your PM. I'll give you a call.

[Sugarmaker]

I just saw a add for Leaders new gassification arch in the Maple Digest. Looks like a very long deep fire box with air injection at the place where the ramp would be pointing at the door?? Cant see nozzles along the sides. Anyone eyeball one of these yet, or have they been out for a while?

On that note I did not respond, ( till now) but sounds like the Force V had some problems. Or is that a rumor? Where's DaveY?

You guys are all doing fine with the forced air over fire. I'm just jerking your chain a little:) Thanks for putting up with my crap! If there wasn't a discussion there wouldn't be a need for this forum! Which I think is a get place to learn, debate, and improve.

I agree with Brandon, If you build a AOF system, no matter what type of style, the proof will be next spring when those that did, can spend more time on the trader.:) right after they spend more time with their families.

Have a great night.
Regards,
Chris

[Brent]

Chris
The guys I bought my used rig from told me that they looked into the Force 5, the new Leader Vortex and the Intesofire. They say the shop was full of Force 5's being rebuilt. In view of that bad news they also did not want serial number 3 or 4 Vortex, so they went with the Intesofire, which is proven and improved over a few years.

I think all the latest high performance rigs, at least the pictures I've seen, have a row of nozzles across the top of the slope, pointing toward the door. I wouldn't think you'd want a lot of air their, but that would be the last point to enrich the O2 before the gasses go under the flues. I'm scratching my head about how to do that. Maybe the same way I did in year one with the 2x6. Drill a 1-1/2" hole in thru the side, stick in the 1-1/2" round stainless tube, put a support on the opposite side and I can aim it where I want and dril or plug holes till I'm crazy, and put a regulating valve on it too.

[Parker]

All right,,I have read the posts and printed out the proctor paper...now I have some questions,,,#1 how critacal is the damper in the stack? My stack is an absoulte BEAR to handel (24"),,The paper says use a barometric pressure damper (sounds real expensive)...
#2 Paper says preheat your air in the stack with a heat exchanger,,,,,Now,,,I thought cold air had more oxygen, burned better,,,and agine,,,doing work inside the stack,,and building a heat exchancer in it would be VERY difficult,,,
#3 Has anyone done this with a 5 foot wide rig, and did they go with the 2 rows of air pipes around the firebox? If not, what were the results?
#4 I have the recomended blower for this mod. But was not really that impressed with the ammount of air it moved just blowing under the grates and into my front (airtight)...I thought the duct work I had was too small to move the volume of air the blower was producing,,,BUT,,,it is bigger than what is recomended in the paper
#5 Where can you buy-salvage from another application,,the 2" window-sight glass recomended in the paper?
Thanks for for the input and this enlightening thread..Parker

[twofer]

Last spring I saw the Leader Vortex and to be truthful I was not all that impressed. For a rig that expensive I would have liked to have seen digital controls and also have them mounted either on the arch or at least in a nice enclosure that could easily be mounted. Heck even my $4k gasification boiler for my home has digital controls where I press a button to shut the fan off for loading or modify fan speed on the fly.

More importantly the design of the air injection seems questionable to me as there looks to be a lot of air being injected low into the coal base which seems to me would do little to increase efficiency. From my amateur understanding of gasification the increase in combustion efficiency occurs from when you have a separation of primary and secondary combustion whereas their unit seems to just swirl the entire firebox. Maybe it does work like they claim but for such a new design unlike any others I'd want to see a controlled study done to get hard measurements on efficiency like they do for gasification boilers.

I was also able to see the Force 5 in operation out in Vermont and IMO that is a better design. You can visibly see the secondary combustion in the unit and the stack temps run quite a bit lower than the Vortex, which I guess could have just been how the Leader rep was running their unit.

[Brent]

I have frequently tried to understand what benefit a draft damper would be and come up empty. That doesn't mean it wouldn't help. But I'm one of those types that does not often blindly follow. So I did not put one in my little rig... and still got something like 50% wood savings. I also did not pre-heat the air. I started off with the blower on the floor of the sugar shack, with the intention of eventually putting it up in the rafters to take the warmest air. ( I don't have a cupola) but the noise was too much so it went outside and stayed there. This year I have a quieter blower and hope to at least get the air intake high above the stack in the rafters, if not the whole blower. This seems like a good payback in efficiency, but to put a heat exchanger in the stack, it would need to be copper or stainless and that expense just seems too high. If you think you stack is bugger to handle now, think about adding a few hundred pounds of heat exchaner !!! Wow !!

As for oxygen content, I don't think heating the injection air would cause any change.

As to the new Vortex, what you report does sound like a bit of an improvement over the Inferno but not much. I think any air going up through the wood or blowing directly onto the wood will certainly make it burn faster and hotter, but do little for efficiency. I believe you have to inject air several inches above the fire where the combustion is starved of O2. I think you could even get a re-ignition under the flue pans if you did not have air injected directly over the fire.

Hmmmm. One tube sliding over another to open and close some tubes under the grates and a peep hole to see
if I get re-ignition. If it worked I could a least adjust it before I start in the morning. Then again, why would you want re-ignition that far back when it has so little opportunity for the resulting heat to be absorbed into the flues. Hmmmm.

[maple flats]

I did not do the barometric damper yet. My system has no damper and the results are very impressive. I do plan to make a barometric damper in the future. Try it without first. The barometric will further enhance the performance.
To install a barometric you do not need to remove the existing stack for any reason. You would make the unit to fit on like a saddle fitting. Then trace the outline to mark the install location. Then just inside the mark (at least a safe margin smaller hole), drill a hole and cut the outline either with a pair of offset tin snips or better yet use a sawzall (and ear plugs) to make the cut out. Then hold the saddle in place and drill for rivets or screws to hold it in place. Use SS screws or pop rivets to anchor it. Use more that 1 rivet in each anchor point for safety.
To make the barometric damper, study one on an oil furnace and just size it to your stack size. It will not be hard to make but 2 points. The damper must pivot freely and you must be able to fine tune the balance by moving a suitably sized heavy weight in or out. I suggest you attach the barometric just above the top of the transition where the final diameter starts.

[Brent]

Thanks for that detailed explanation of how to install.

Can you explain what it is that the damper will do to enhance performance? I can recall them from many days ago, very many days ago, and it seemed that they allowed room air into the stack, and reduced the amount of draft that the stack would normally induce.

It seems a bit backwards to me to be putting blowers in to increase the draft and then a damper to reduce it. I've got to be missing something. I have not seen one offered in a maple syrup equipment catalog yet. (may have missed that too !)

[twofer]

...

Can you explain what it is that the damper will do to enhance performance? I can recall them from many days ago, very many days ago, and it seemed that they allowed room air into the stack, and reduced the amount of draft that the stack would normally induce.

...



The idea behind it is to regulate the amount of draft so that it is consistent. With varying heights of chimney and weather conditions the amount of draft from the chimney will vary along with it. Too much draft can pull more air through the blower and increase the speed of the air moving through the arch and make tuning the amount of air harder, as well as, decrease combustion and pan efficiency. The decrease in combustion efficiency comes from the inconsistent amounts of air getting blown to the fire. The decrease in pan efficiency comes from the increasing air speed that lowers the amount BTU extraction from the shorter amount of time that it is in contact with the pans.

At least that's how I understand it. I'm no expert but I did stay in a Holiday Inn last night. :)

[Brent]

Twofer

Thanks for the expanation. Off topic a bit but on the hotel thought: My last hotel stay was in Vermont, where the breakfast was do-it-yourself waffles.
The Pam like waffle iron spray had "oven baked aroma" added. The syrup, with maple leaves on the jug, was fructose with "added flavors", and the butter was, well, not butter but hydrogenated vegy oil. Sacriledge. In Vermont !!!!

One the damper, that's about what I expected. The problem I have is that I think we are so far from finding optimum performance, I don't think adding a damper to maintain non-optimum, is worth the trouble. I would rather spend some time and effort trying to quantify how efficient any system or blower speed is. I'm starting a search for an oxygen sensor that I have put in the stack.
My thinking is that we keep adding air above the fire until we get some unconsumed O2 going up the stack. Then we'll know that no unburned smoke or wood gas is going up. I'll happily invest a few hundred dollars to find out how to set the rig up. If an O2 sensor is a few thousand dollars, then I'll be looking for a Holiday Inn too !

[twofer]

I'd like to get an oxygen and carbon dioxide sensor in the stack but until I do I plan on adding a thermocouple (thick sheath) between the syrup and flue pan. Once I get the boil rate in the range expected I plan on adjusting the over fire air until I no longer see an increase in temperature.

[Sugarmaker]

towfer,
Sounds simple but elegant. Hope your trials work with the thermocouple between the pans! Interesting!

Going into the crazy zone for a minute or two just hang on and dont try this at home!

I have thought about this a little too much so here is where the crazy ideas come out.
What if the AOF was really AOF (Air Over Fire) not ABF (ABF= Air Beside Fire) What if the air was directly over the center of the fire box pointing straight down into the fire? like a row of air nozzles running down the center of the bottom of the front pan pointed vertical down? I know..... don't shoot me, there are 17 reasons why this wont work!

We that have under the fire blowers can already get a lot of fresh air to the fire. Maybe at the wrong place but still a lot of fresh air. the fire is not starving for air. It burns like crazy with a under the grate blower. The Leader catalog still calls the under grate blower system a wood saver?

Anyone see the Geico (sp)wood chuck commercial. It kills me:) Looks like me firing the old King arch!

Regards, and have a great evening
Chris

[WESTVIRGINIAMAPLER]

Chris,

With an air injection at the center top of the firebox would burn out pretty quick unless it was ultra protected and would block the heat getting to the area of the syrup pan it blocks, so it would be counter productive and doubt we'll see much like that from the manufactures.

I did not add a sight glass to mine and may in the future, not really concerned about it at this point but would like to try one.

[Brent]

I was just boring my wife with some re-cap of this thread and then the light came on.

We can have our cake and eat it too.

If we have an oxygen sensor in the stack near the stack thermometer for example, it would tell us when we have reached maximum thermal efficiency... ie add air over the fire until you actually get some oxygen up there. Everything that can burn will be burned.

BUT

then we can turn up the blower under the grates, cook the wood to get more wood gasses and particulate, then the O2 sensor will show nothing. Then crank up the blower for air over until you get some O2 and you'll be burning both hotter and still a maximum efficiency.

Gotta .... really gotta ... find and affordable O2 sensor (that can stand the heat)

[Brent]

Brandon

I'm with you, I don't want anything, or at least much, between the fire and the pans.

But so far as lasting, the stainless tubes I used last year took a lot of hot fires, up to 1350 top stack temp if I recall correctly, and they came out last week looking just like new, except for the same yellowing that you get on a stainless stack base. They have relatively cool air being pumped into them. All this might change if the blower feeding them quit and the blower under the grate kept going and the temps really skyrocketed. Last year I did not have a blower under the grate, but this year with the Inferno things will be different.

PS the 1-1/2" stainless tubes were unsupported at the door end of the firebox and did not warp, droop or otherwise look like an ED commercial.

[Parker]

I have dial up so it is almost impossibel for me to post pics,,but I can e-mail them,,I took a bunch of pics of an evaporator a few years back that had a VERY radical AOF system (and sight glass).. I think the pics of it would be helpful-useful to this thread,,if someone PM's me their e-mail adress that will post the pics in this thread Ill send you the pics....This desgine is not for everyone,,,but,,might help some..I have not seen another rig set up like this one since....

[Amber Gold]

Catching up on this thread and it's got me thinking about building one of these. With the RO I don't need the increased evap. rate or efficiency, but it would be a neat project to see how well it works.

If I did it, it would be the last thing I did once all my other projects are complete. I would modify my Grimm arch with the AOF system Could I get by with the standard doors?

[twofer]

Catching up on this thread and it's got me thinking about building one of these. With the RO I don't need the increased evap. rate or efficiency, but it would be a neat project to see how well it works.

If I did it, it would be the last thing I did once all my other projects are complete. I would modify my Grimm arch with the AOF system Could I get by with the standard doors?

I asked the combustion expert that worked on the high efficiency arches for D&G the same question and he said that it is still possible to realize some efficiency improvement without an air tight arch. Though the better you can seal it up the higher the efficiency improvement will be.

[Sugarmaker]

These are some pictures that I posted for Parker due his slower system.
Parker you can take it from here. (I should have copied the words from your email)
I thought it was interesting to see how they took out the ramp and extended the fire box under the flue pan.

Chris

[nymapleguy607]

This setup looks similar to the hurricane style arch setup. I think most if not all the commercially built High efficientcy wood arches do not use a ramp they rather extend the firebox back under the flue pan. Not so much to increase the amount of wood you can add rather give the wood gasses and oxygen more space to mix. The firebox layout is similar to how I want to build my new arch.

[Parker]

Thanks for posting the pics chris...I never saw this rig boil so I dont know how fast it was,,,,Thought it was interesting how they had it set up,,as I recall 2 blowers fed the front (hollow doors-each door was a hollow box about 4 inches thick made of 1/4" plate- with slits cut in them so air would blow on the fire- air blew into the hollow tube below the doors which had an opening in its top,when you closed the doors this opening lined up with the opening in the bottom of the door,,air exited the door thru the slit in the door, blowing on the fire),,1 blower blew under the grates,,and 2 blew in from the back of the arch towards the doors,,as you can see there was no air down the sides of the arch,,the firebox had been extended about 2 feet under the flu pan,,they were burning 4 foot wood,,This was a standerd arch that they modified......would not bee too hard to make a front like this set up

[Sugarmaker]

Parker,
No problem, Sorry it took me a while to post the pictures.
Interesting that the blowers that they are using are not HP paddle blowers but large squirrel cage type blowers.
I think this looks a lot like the picture of the Leader Vortex design.

Regards,
Chris

[Brent]

Yeh
they look that same as on my Leader Inferno and the Steamaway.

[twofer]

Are the air ports all the way to the back of the arch? If so I question increasing the distance between the primary combustion and the secondary combustion for two reasons. The first being that the gasses have passed over much of the arch and you're reducing the amount of pan contact they're going to have after achieving secondary combustion. And the second being that it would be possible to not even achieve secondary combustion if the gasses have been cooled down below the 1200°F threshold from all the pan contact they've had.

[WESTVIRGINIAMAPLER]

I did get my arch finally put back together today and did a test fire to clean out the pans. Everything worked really good and no problems or disappointments with function of everything. Not sure how it will perform once I get to boiling sap. I only loaded it with wood one time after starting it with just a partial firebox of a few pieces of bark and small scrap wood. Did seem to burn quite a while but never even got the firebox hot enough to really test it out and kinda hard with 10" of cold water and milk stone remover from the start in the pans. I left the pans dirty in the spring when I finished boiling to I could clean them when I did a test fire.

Be interesting to see what happens when I get sap in the pans and how it performs. Looks like the wood savings will be there and hopefully won't give up any gph, but time will tell.

[802maple]

Interesting concept, this air over the fire. Does anyone really expect that air over the fire will really work? LOL

[Thompson's Tree Farm]

:lol: Jerry, I've been waiting for you to chime in on this. Just wasn't sure how you would wiggle in. Thought maybe Parker's Pics were of an old prototype or something.

[Brent]

Of C o a r s e it will work. Our elevation here is about 950 ft. We've got at least 60,000 ft of air over our fire. Shouldn't that be enough ????

[WESTVIRGINIAMAPLER]

Interesting concept, this air over the fire. Does anyone really expect that air over the fire will really work? LOL

Jerry,

It is basically the same concept of the Intens-O-fire arches you developed other than my firebox/combustion chamber isn't as big, except I have air on all 4 sides instead of just 2 and we know how good the Intens-O-fire arches are!

[Brent]

twofer
I think there are a few problems with this rig, as I try to interpret what I see.

First it looks like there is a huge gap between the bottom of the flue pans and the floor of the arch. Hot air a foot under the flue pans is not going to heat anything but the night sky.

Secondly, I agree that the air injected virtually at the bottom of the stack, IF it ignites, will not have a chance to deliver very much heat to the flues. If it does not ignite it will only cool the pans there.

Like the cookie monster, this thing will be a wood monster with all that air going through it will eat up a lot of wood.

[802maple]

Brandon, it sounds like you did a good job and I think you will be very happy with it. I am presently doing a retro for another arch much like you have done.

[Parker]

THe air injection at the rear of this arch is not under the stack,,,This is a 12 foot long rig,,had 2 cross flow 2 foot wide pans, then an 8 foot flue pan,,the air came into the back of the arch about 5-6 feet fron the front...from what I herd from sevral people this was a very fast rig...

[802maple]

The manufactured arches have their air come in at about 2/3rds the length of the total arch, if that helps anybody that is building or remodeling.

[maple flats]

I'm sure all of you understand the air over fire concept, but just in case there is anyone new to the idea, here is a Readers Digest type explanation.
When burning wood the wood does not burn, it is the wood gas given off from the wood because of heat. To witness this, just light a match and look at the flame. It hovers above the wood or even cardboard match. The air over the fire is burning wood gas that is already there but is passing up the stack unburnt because it ran out of air to burn. The see this, look at the top of your stack during a hard boil with the lights off. You will see a ball of flame on top as the hot gases get the needed air to burn. When we add the new air over the fire we can burn these gases under the pans where it can do some good.
I hope I didn't offend anyone by giving a little explanation, but I intend it only for anyone who is not on the right page yet.

[802maple]

I have a fair idea as to how it works, but thanks for the explanation. I might give it a go sometime. LOL

[Brent]

I've had some emails and comments that using stainless tubes is too expensive. The 9' long tubes I used last year
cost a grand total of $ 136. Canadian. for the pair. They were 1.5 diam, 0.12" wall. They were unsupported on the end nearest the doors and suffered no corrosion or distortion.

[Sugarmaker]

Brent,
thanks,
May look at that option too.
Chris

[Sugarmaker]

Folks,
As usual I'm making something out of nothing! I have a AOF system in place on the 3 x 10 but with several loose ends yet to complete, most of which need dollars thrown at them. Hopefully we will get it operational for the 2011 season. Thanks for all the ideas and suggestions on this AOF thread.
Hoping the wood consumption will be reduced somewhat as others have witnessed using these systems.
Regards,
Chris

[sweetwoodmaple]

http://mb-soft.com/juca/print/315.html

I have been looking at all these AOF posts and wondering if it is the right thing for me to try. I have been a bit skeptical with the efficiencies gained by adding AOF by itself without the airtight arch, arch design changes, etc.

I did some research on one, two and three stage combustion. I think this article brings up good points about combustion air preheating. Seems like cool air that is not pure oxygen (even added with AOF) will have some trouble gaining efficiency without significant preheating.

For me and my little operation, I'm going to stick to my low tech traditional rig. I equate this AOF to adding a NOS bottle to my car just to get to the grocery store a few minutes faster. So little to be gained compared to the risk of burning the place down. ;)

P.S.....my pellet stove fire box has the AOF concept. There are larger holes in the bottom and small holes around the permimeter pointing into the flames.

[Sugarmaker]

Brian,
Thanks for including the article on secondary combustion. This has been a interesting AOF project that I am working on, but only time and some boiling will tell if there will be any gains.
Hope your getting things ready for the 2011 season!
Regards,
Chris

[twofer]

http://mb-soft.com/juca/print/315.html

I have been looking at all these AOF posts and wondering if it is the right thing for me to try. I have been a bit skeptical with the efficiencies gained by adding AOF by itself without the airtight arch, arch design changes, etc.

I did some research on one, two and three stage combustion. I think this article brings up good points about combustion air preheating. Seems like cool air that is not pure oxygen (even added with AOF) will have some trouble gaining efficiency without significant preheating.

For me and my little operation, I'm going to stick to my low tech traditional rig. I equate this AOF to adding a NOS bottle to my car just to get to the grocery store a few minutes faster. So little to be gained compared to the risk of burning the place down. ;)

P.S.....my pellet stove fire box has the AOF concept. There are larger holes in the bottom and small holes around the permimeter pointing into the flames.

No offense but to be blunt that paper is biased and uses pseudo science to further it.

The bias comes from trying to sell their JUCA product (believe they out of business?) and is readily apparent when they things like:


"Some currently available products do seem to be able to support secondary combustion SOME OF THE TIME and TO A LIMITED EXTENT."


And it represents more material that must be pre-heated so as not to chill the smoke to below 1200°F. Getting back to our example, if we mix our 1400°F smoke with an equal amount of room temperature secondary air, the resultant temperature of the mixture will be less than 800°F, far less than the necessary 1200°F. No reaction. Poor efficiency. A lot of creosote. A lot of pollution. Bad. You can probably see that you are going to need a source of secondary combustion air at about 1000°F or higher under these conditions. A pre-heater will be necessary to boost the room air to 1000°F.

That is a pretty broad stroke to claim that every other design on the market doesn't work or only works parts of the time and even then doesn't work very well. Well a picture is worth a thousand words so below you'll find a picture I took of the secondary combustion occurring in the gasification boiler I use to heat my home, that does not preheat the air. The picture isn't very good because it is off my cellphone but the flame you see is burning so hot that it is blue/white and the little bit of ash that is left over sees some fusion. If you look up my chimney you know what you'll find? A bit of fly ash and no creosote buildup.

http://img38.imageshack.us/img38/5323/mysecondaryburn.jpg

As you can see it is entirely possible to achieve secondary combustion without preheating the air and that their second statement that I quoted is false. You've probably proved it yourself if you've ever opened up a smokey wood burning appliance and there is a big puff. That is essentially secondary combustion.

[Gary R]

Brian, I don't know squat about combustion. Myself and a few others on the trader added OAF. I'd say we're very happy with the results. Can't quantify anything, but it sure does burn hot. If you stop by this spring, the first thing you'll ask is how can I make all that steam with no fire (smoke)?:)

[maple flats]

I still say, Try it, you'll like it. I noticed the link I ref in post 2 and a few others takes you to the same report as the link WVM posted, even thou they are different routes.

[sweetwoodmaple]

http://msuextension.org/publications/HomeHealthandFamily/MT198405HR.pdf
Sorry about that....I was reading something like this (like I posted above), then went over to the JUCA stuff. Lots of sales pitch and attitude. Anyway, no offense taken...it's fun kicking this stuff around. If anyone offends easily, they shouldn’t be posting! ;)

I have no doubt that we are getting secondary combustion. I don’t have to clean anything but the flues on occasion for my 3 x 10, though I run it like a freight train!
I could take a photo of my pellet stove, which also burns very efficient with just a bit of fly ash and no creosote.

Honestly, I’m not after super clean burning. I want the best boiling rate possible out of my rig with minimal creosote. I’m not even that concerned about wood consumption, though as others have said, the phrase “wood saver” with air under fire designs seems like false advertising. Saving some wood would be nice, but if I could step up my GPH 20-30%, then I’m all ears.

Back to the pellet stove example, the efficient burning there is geared towards no creosote buildup while going through all the heat exchanger and exiting the stove at around 300 degrees. If the stove wasn’t extremely clean burning, this would spell disaster at such low temperatures.

Going back to sap boiling, I’m not sure we are after the same thing as a pellet stove. From my limited experience, it seems that flame contact with the pans is the ticket to the maximum boiling rate. Any time my flames don’t go all the way back the flues, the boiling tends to slow down. This seems to make sense as secondary combustion occurs at 1,100 deg F and the flames themselves are up to 2,500 deg F.

I watched some videos of a Force 5 unit running, and it does seem impressive. The fire box seem longer, so that helps with the flame contact. I’m just not sure it’s worth the risk for me as I’ve heard you can have major bad things happen if the fans stop under full boil.

All kidding and joking aside…Perhaps you folks that are doing the AOF would consider using the 800 deg F exhaust air for heat exchangers as the combustion would be so clean and not build up. Maybe a secondary boiler system with coils inside the stack leading to an open tank with a bubbler?

[Gary R]

I was at Dave Y's Force 5 boiling demonstration. Lapierre reps were present also. From what I recall, the heat to boil was radiant, not flame contact.

[twofer]

http://msuextension.org/publications/HomeHealthandFamily/MT198405HR.pdf

...

Back to the pellet stove example, the efficient burning there is geared towards no creosote buildup while going through all the heat exchanger and exiting the stove at around 300 degrees. If the stove wasn’t extremely clean burning, this would spell disaster at such low temperatures.

Going back to sap boiling, I’m not sure we are after the same thing as a pellet stove. From my limited experience, it seems that flame contact with the pans is the ticket to the maximum boiling rate. Any time my flames don’t go all the way back the flues, the boiling tends to slow down. This seems to make sense as secondary combustion occurs at 1,100 deg F and the flames themselves are up to 2,500 deg F.

I watched some videos of a Force 5 unit running, and it does seem impressive. The fire box seem longer, so that helps with the flame contact. I’m just not sure it’s worth the risk for me as I’ve heard you can have major bad things happen if the fans stop under full boil.

All kidding and joking aside…Perhaps you folks that are doing the AOF would consider using the 800 deg F exhaust air for heat exchangers as the combustion would be so clean and not build up. Maybe a secondary boiler system with coils inside the stack leading to an open tank with a bubbler?

IMAO that is an excellent article.

You are correct about the low flue temps not being a problem when you have a high efficiency system. When my boiler is up and running full steam ahead (pun intended) the flue temps are < 350°F. The reason they are not a problem is because any creosote causing gases have been combusted and no longer pose a threat. The reason evaporators don't have a problem with creosote is not because of higher combustion efficiency but rather they are being run so hard and hot that the creosote causing gases never get a chance to condense in the chimney.

I definitely agree with the Procter guidelines and trying to preheat your air as it will increase efficiency even further. While the boiler in my home does not do it and still achieves secondary combustion I still see that as a flaw.


I was at Dave Y's Force 5 boiling demonstration. Lapierre reps were present also. From what I recall, the heat to boil was radiant, not flame contact.

When I attended the combustion efficiency talk at the D&G open house this year the combustion expert (I forget his name) was talking about this. He said they actually modified their high efficiency arch so that more the bottom of the pan was exposed to the face of the flame. The reason? Because people were complaining they were not seeing boiling (bubbles) at the back of the pan and claimed their boil rate was suffering. He claimed that the boil rate was not affected and that they went ahead and modified the arch anyways to deal with the psychological affect of not seeing bubbling at the back of the flue pan.

[Brent]

No question the JUCA guys had an axe to grind but I think this supports some of what I read elsewhere, that we should be striving more less volume of air, but at higher pressure (through smaller nozzles) and through more nozzles so it will penetrate and reach lots of the tops of the flames, without the chilling effect.

Last year I could see a difference ( but not measure anything) when I turned the tubes from point the air horizontal under the pans, to down into the flames at about 45 degrees. I recently found a source for pyrometers ... high temperature probes good for up to 2500 degrees. Now I want to find a display to give me a temp reading. Lots of dreaming and not much progress.

[nymapleguy607]

No question the JUCA guys had an axe to grind but I think this supports some of what I read elsewhere, that we should be striving more less volume of air, but at higher pressure (through smaller nozzles) and through more nozzles so it will penetrate and reach lots of the tops of the flames, without the chilling effect.

Last year I could see a difference ( but not measure anything) when I turned the tubes from point the air horizontal under the pans, to down into the flames at about 45 degrees. I recently found a source for pyrometers ... high temperature probes good for up to 2500 degrees. Now I want to find a display to give me a temp reading. Lots of dreaming and not much progress.

Brent
What did you find out when you turned the air tubes from almost horizonal to 45 degrees?
Could you tell a diference wether it was good or bad?

[Brent]

Brent
What did you find out when you turned the air tubes from almost horizonal to 45 degrees?
Could you tell a diference wether it was good or bad?

There was no real way that I had to measure much. But I can tell you that the more downward the jets aimed, the more fire made a lot more noise, like a deep rumple, and I have literally lost half my hearing, so if I could hear it, it was significant.

I never actually aimed the jets very high. I didn't want to inject cool air right below the pan. After reading the articles it seems that we need to aim the jets right near the tips of the flames, with enough air to re-ignite but not so much that we cool below the re-ignition temp. I think it will be easier to keep the fire at a consistent height by using smaller more frequent firings, that to be always trying to re-aim the jets. ( I used round tubes that ran right out the back of the evaporator so I could just twist them)

Too much theory and not enough data.

[Sugarmaker]

I finished some minor stainless steel MIG welding and then air tested my AOF TRS today and found that I did have air coming out the right places (nozzles) so that's good!:) Not sure it will be enough air, or if this system will work? Real test results will be in the spring on several hundered gallons of sap in the holding tanks.
Next will be to apply some insulation and then I should be able to set the pans in a week or so. That will allow me to get the rig back together and the pans in place. May do a test boil when I get the AOF blower purchased and installed.

That overhead rail system to lift the pans by myself has really allowed me to do some much needed work on the old arch.

Hope things are good out there!
Regards,
Chris

[jasonl6]

I just recived my blower off ebay. I bought it from seller NPS . He has several more posted and the prices are cheap. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390265218869&ssPageName=STRK:MEWAX:IT

I ought the 4c108 which is the same that UVM suggested here http://www.uvm.edu/~pmrc/Combustion.pdf for a 3' arch Grainger # 7C447. I have a 30"X8' arch and overkilled it a little but the price was great.

I would highly suggest this seller to anyone looking for a blower.

Jason

[WESTVIRGINIAMAPLER]

That's the same blower I bought to install on my 2x8 and I got it off of ebay. I installed a 1 hp A.O. Smith 3450 rpms on it.

[jasonl6]

I'm still looking for a 1 hp motor. Tried an older heavy duty 1/2hp that weighs like 40lbs but it kept fluttering so i need the 1 hp.

Have you had yours running yet? Do you have your air manifolds done? How is the pressure at the nozzle tips?

Jason

[WESTVIRGINIAMAPLER]

I have mine finished and did a small boil to clean up the evaporator and it works good. As far as pressure at the nozzles, it seems good but I don't have any way to measure it. Guess I know more in about 3 months, it worked good on test boil.

[Brent]

Correcting my previous post.....
This blower seems to be a max pressure of 7" SP / WC.

[nymapleguy607]

The spec on the blower referenced above is 28" WC. To me that should do a great job. Thats roughly 10 times a furnace fan output pressure wise.

Brent
How can you tell the spec on that blower. I looked at the same one at Grainger and they said that it would work up to 5" static pressure. Is static pressure and WC the same thing?
Sorry to bug you about this but I am trying to find a High pressure blower for my 2x6 and am having trouble with the specs. Thanks Jeff

[Brent]

Brent
How can you tell the spec on that blower. I looked at the same one at Grainger and they said that it would work up to 5" static pressure. Is static pressure and WC the same thing?
Sorry to bug you about this but I am trying to find a High pressure blower for my 2x6 and am having trouble with the specs. Thanks Jeff


Good work. I have retraced the search I did and now I have no idea what gave me the idea that it was 28".

I beleive WC and SP are the same.

To get a real high pressure blower, search Ebay for GAST regenerative blowers, there just happens to be lots of them there these days. These babies pump up great pressure ... the one I picked up is rated 58"WC.
Go to www.gastmfg.com/blower.html (http://www.gastmfg.com) to veryify the specs.

[nymapleguy607]

Well I bought a blower for my new arch I'm building. It is a dayton similar to Jason and Brandon's the only difference being this has a 9" impeller. I am just about ready to go to work on the air dampers, I just need to pick up the sheet metal and I will start. I hope to have everything completed in time for the season but time is running out quick.

[jasonl6]

Has anyone used a reostat instead of dampers? I have a furnuce blower for my under air and i think if i use a reostat i can control my over air pressure with that.

Jason

[nymapleguy607]

Jason
Correct me if I am wrong but are you planning on using 2 seperate blowers? I tried this last year and didn't have very good luck, my under fire air blower was having a hard time pushing air against my over fire blower. My new arch will use the same blower to supply over fire air and under fire air as well as air through the door frame. Just a thought.

[maple flats]

I use 1 blower with valves and it works great. I never tried two, but my guess is it should work. Even with high pressure you are still at fairly low volume. The draft on the stack while firing will more than prevent any back flow.
As I said before, once I get the fire going full tilt I do not even need to sllower or air flow to open the doors. Last year I noted a slight inward draft thru the fill doors, never got any sparks or smoke out the fill doors with the blower on. The front on my rig is not even air tight and hi pressure still works great. Someday I might add an airtight front to increase boil even more and keep less heat loss out the front but I have many other priorities before that.

[jasonl6]

I never thought about the difference the two blowers might make. Maybe i'll try just one blower w/ valves.

jason

[Sugarmaker]

Added some rope type pan gasket at desired areas on the AOF system. Just about ready to reset the pans on the arch. Then scrounge for a blower and some plumbing parts to move the air to the evaporator.

Did get a chance to see a 3 x 8 being converted from wood fired to natural gas in the very near future. That would be the hot set up. What to do with all that spare time???:)


Regards,
Chris

[nymapleguy607]

Brent and Dave
I was currious what size would are you burning since you started using AOF. Have either of you tried larger pieces and what were the results?

[twobears1224]

i,ve posted this before..if you wanta learn about blowers heres the website to study. http://billpentz.com/woodworking/cyclone/index.cfm

delbert

[Brent]

NYMapleguy

I hav been burning mostly hard maples and beech, cut to about 2' lengths and split to about the size of my wrist. This year will see us firing up a bigger evap (2 x 6 vs 2-1/2 x 8) so we're cutting to 32" and likely going to be a bit bigger in diameter.

[nymapleguy607]

Thanks Brent
After reading your old threads from last season and your 15-20 min firing times I was curious what size your wood was.

[Brent]

Jeff
Those firing times we an indication of better burn efficiency. At risk of repeating myself, as the season went on I found that as I shortened the firing times with smaller loads, I "seemed" to maintain more consistent stack temps and boils and the black smoke I got right after firing, (indicating that too much cold wood had killed off the secondary combustion) became almost non-existent. I beleive we need to rethink the old wives tale that opening the door leads to cold fires. I think it's big piles of cold wood going in that leads to cold fires. In fact last year I used to stand the next load of wood in front of the arch and let is soak up some of the outrageous amount of heat I was losing throught the un-insulated iron doors.

[jasonl6]

Did get a chance to see a 3 x 8 being converted from wood fired to natural gas in the very near future. That would be the hot set up. What to do with all that spare time???:)

Get a second job to pay for the fuel. Our neighbor has a nat gas fired arch. told me it cost about $4,000 last year for his season :-/

[Sugarmaker]

Get a second job to pay for the fuel. Our neighbor has a nat gas fired arch. told me it cost about $4,000 last year for his season :-/
I think the rig I saw being converted to natural gas will be run at zero fuel dollars as long as the gas in his new well holds out!:)

Regards,
Chris

[Sugarmaker]

Folks,
12-8-10 Completed the AOF TRS system to the point I could reset the pans tonight. Thanks to S Durff for some insulation.
These are some early shots of the fabrication.
I have several more pictures that will follow. Hope the size isn't a problem, I did not shrink them:)
Yep its more than a concept! Its "real in steel". Time will tell how it may preform.
Regards,
Chris

[Sugarmaker]

Some additional shots of the AOF TRS.
Cross tube is insulated. Perimeter tubes are not insulated but have rope gasket material above and below. Rail Air tubes have additional 3/8 supports welded vertically through the tubes every 12 inches.

Thanks to several of the traders for ideas on design issues.
Regards,
Chris

[whalems]

Chris, Looks good! I keep debating on using square or round tube. I will most likley put mine lower in the firebox but then again I am still rebuilding so there are no firebricks in my way yet. Is your tubing stainless? mike

[Sugarmaker]

Mike,
Yes stainless tubing. Round was much cheaper and I had 30% on hand. Sq. would be easier to fit up and fab.
Chris

[Dennis H.]

Very Nice, I like the idea of adding it to the top of the arch rails.

Great retro-fit idea for any evap.

[Dave Y]

Chris, you need to go to work for an evaporator company. That looks better than some manufactured units. All you need to do now is drop your sack base 8 inhes and you will have a "vortex". Nice work!

[Rhino]

Really some nice work and a great idea. Nice thing is its easy enough to add more nozzles if needed. Keep us posted if you do a water test boil.

[Sugarmaker]

Guys some AOF shots at different angles. Some words to follow in next post.
Chris

[Sugarmaker]

Dennis H.,
That was one of the concepts, that it could be added to arch relatively easily. It still wasn't that easy. But I'm lazy and did not want to take the bricks out.
Dave Y,
Good to here from you. Not sure I understand about droping the stack base? But I did raise the pans 2 inches and added more ramp under the flue pan.
Rhino,
Thanks. Yes nozzles could be added as desired. I would like to do another test boil over the Christmas holiday.
Some more data on AOF TRS (Top Rail System) to follow:
Cant seem to post real long text messages any more.
Chris

[Sugarmaker]

Air nozzles are pointed down at about 45 degrees. They are 1/4 I.D. sst tubing 3/8 O.D.. The air hole at each nozzle in the rail tube is about 3/16 dia.. 30 Nozzles 10 on each side, 5 at the front, 5 at the rear.
Pans are lifted about 2 inches. Air tubes (rails) are round 1.75 O.D. sst. 45ed at the corners then MIG welded. Air inlets will be at rear of arch on both sides and pass on each side of the rear flue pan. These inlets will be connected to the blower system. Probably another SPA blower mounted either under the arch or outside next to the one for the WRU.

If this thing explodes and melts into a pile of mush I'll be te first to say well that didn't work out.
Chris

[Sugarmaker]

Some one ask how will I know when its (AOF) working? I said I really don't know what to look for but would use these four things as positive indicators:
1. No big red fire ball at the top of the stack. (Burning more gases)
2. Very minimal sparks coming from the stack. (Burning more completely)
3. No reduction in the boiling rate. (Not cooling the pans)
4. The wood pile is not going away as fast as normal. (less wood per gallon of product)

Old arch, old pans, old sugar maker, seems to be a theme here!

FYI: Cheryl and I will be celebrating our 39th wedding anniversary on Saturday. We may go out to dinner after I get back from deer hunting!
C'mon guys who says all I do is maple stuff Ya have to hunt some too!
Regards,
Chris

[Dennis H.]

Wow deer hunting on your anniversery!! She's a Keeper!:D
I hope you get cleaned up for the outing to town 1st!

Great to hear that you have made it 39 years.

[Dennis H.]

Where did you pick up the spa blowers? Do you have any pics of them?

I see that you have 2 inlets to your AOF, They are going to be hooked up to the same blower right?

[Dave Y]

Chris, You would have to reconfigure the back of the arch to force the flame down and allow sparks and ashes to fall out before they go up the stack. this will also keep the hotter air under the pans longer and the cooler air will drop out and up the stack. You are a smart guy if you think about it you will figure it out.

[S Culver]

Has anyone thought about the blowers that are used to inflate between the plastic on greenhouses? They are quite, the flow is adjustable with a plate that covers the inlet. The motor stays at a constant speed. They are already plumbed for I think a 3" outlet and The last one I bought has sat on the dirt floor of the greenhouse for 3 years getting sprayed with water, no problems. I think they are in the $ 70.00 range

[Sugarmaker]

Dennis H,
Google Aqua pro blowers should find info on them.
http://www.aquaprosystems.com
I know these (spa blowers) are not producing the very high cfm (120) that some of the other blowers mentioned. So you may want to check out the specs from other posts on this thread.
Yes the intent was to hook both air inlet drop tubes to the same blower. The system is not blocked off for right and left flow streams, its all one system. In fact one of the ideas was to put the blower under the arch. That still may be a option since I have power under the arch now. Would just need to run a line out and back for a controller. Or not, maybe just let the blower run wide open and put in some ball valves to control flow??

DaveY,
I think I get the drift on the lowered stack. Mine will be like that but not 8 inches, only 2 inches, then will ramp back down at the back of the pans.

S. Culver,
Do you have info, name of mfg? sounds interesting.

Regards,
Chris

[gmcooper]

S. Culver
The inflation blowers we use on our greenhouses are dayton brand. I think they are only 1 1/2" discharge. They are quiet but cfm I think would be way below what is needed. Maybe there are some way bigger than I use but all I have seen at Griffen Greenhouse Supply are same as mine.

[S Culver]

gmcooper / sugarmaker

The Schaefer that I have is only 60 cfm and Mayerfeld supply is one supplier out of NJ. Dayton is another mfg and they have all sorts of sizes I know the Dayton 4C443A is 100 cfm. I think they also have 180 cfm model. Look on Ebay there are a whole lot of them. Depends on how fast you want to go. Hope thats helpful.

[Dave Y]

I have been Away from the trader for a while and i have been reading old posts. To Clear up the issue whit the Force 5, It had some brick issues. The wrong temp fire brick was installed at the factory. Lapierre correct all of the units in the field at their cost and have rectified the problem at the factory. The are no design issues. If i where in the market to buy another rig it would be a force 5




I just saw a add for Leaders new gassification arch in the Maple Digest. Looks like a very long deep fire box with air injection at the place where the ramp would be pointing at the door?? Cant see nozzles along the sides. Anyone eyeball one of these yet, or have they been out for a while?

On that note I did not respond, ( till now) but sounds like the Force V had some problems. Or is that a rumor? Where's DaveY?

You guys are all doing fine with the forced air over fire. I'm just jerking your chain a little:) Thanks for putting up with my crap! If there wasn't a discussion there wouldn't be a need for this forum! Which I think is a get place to learn, debate, and improve.

I agree with Brandon, If you build a AOF system, no matter what type of style, the proof will be next spring when those that did, can spend more time on the trader.:) right after they spend more time with their families.

Have a great night.
Regards,
Chris

[Sugarmaker]

DaveY,
Thanks for the update on the Force 5, That's a very impressive evaporator. I even gleaned some good ideas off it when I built the hoods for Keith Talbot.
I assume the wood pile is a little smaller now? or is that offset by increased taps? Saw somewhere you were going to have 3000 buckets? That scares the heck out of me, I just could not get the crew together to service that many taps.
Regards,
Chris

[Sugarmaker]

S Culver,
Quote - "The Schaefer that I have is only 60 cfm and Mayerfeld supply is one supplier out of NJ. Dayton is another mfg and they have all sorts of sizes I know the Dayton 4C443A is 100 cfm. I think they also have 180 cfm model. Look on Ebay there are a whole lot of them. Depends on how fast you want to go. Hope thats helpful. "

I have a Dayton 550 cfm squirrel cage blower under the arch now which will be the under fire blower. I will damper it down to provide limited (20%??) under fire air.

Regards,
Chris

[Dave Y]

Chris, The wood pile is 40 cord of the nicest wood you will ever cut. I hope to only burn half of it and make 1000 gal of syrup. although my figures could be off. I have added a steam away though.

[Sugarmaker]

DaveY,
Your scarin me! 40 cords and a steam away on that big rig! WOW! You have been busy. (I call that the less talk more action syndrome) Did you have to raise the roof or was there room to sneak it in?
That will be some evaporator! Hope you have the help lined up! So estimated 50 gallons of syrup per cord of wood. Thats Great!
(make sure you read lawnmowers thread):)

Regards,
Chis

[Dave Y]

Sugarmaker, Not to suggest what anyone should do, but less trader and more work = more syrup. The only way to make more syrup it is to add taps and boiling capacity. The room is large enough I could put another steam away on it and have room left over. It is about 13 ft to the strong backs. The rig is now over 9ft tall very impressive. When I get a chance i will post some pics for you.

[Sugarmaker]

Dave,
I like the "Less trader = more syrup" theory:) Have to get my fix though.
Would love to see some pictures of that big force 5 and the steam away in place. Bet that's a beautiful thing! Surprised you didn't go with a R.O.?

Chris

[Dave Y]

Sugarmaker , the steam away was $15,000 less than the RO. But,in a year or two I will have a 1200 gph ro.

[sapman]

Dave, you sure have come a lonnnggggg way since you bought those aluminum buckets from me! Wish I could get down and see YOUR setup some time. My operation has undergone some changes, but not like yours!

Tim

[sweetwoodmaple]

Ha DaveY...less trader + more work = more syrup. I like it.

I did notice it wasn't more syrup AND more $ in profit. Payback on this stuff is crazy. Yes, larger operations make it up, but oh my the investment.

So, I'm coining "more trader = less debt on equipment". ;)

[Dave Y]

Yes , Guys I have come a long way In a short time. I have discovered I really cant have a hobby! Every thing I get in to becomes a for profit venture. How ever this is the best I have done on any of my Hobby attempts. More syrup does = more profit you just have to be patient on the profit!

[Dave Y]

Sugarmaker, and anyone else that is interested. I posted a couple of pics of the Force5 in my picsa abum. Just click on the link in my signature.

[sweetwoodmaple]

Wow...a thing of beauty. You need your train engineer's hat to run this baby!

And...I must say that you must not be married to or closely associated with an accountant as the ROI on this deal would scare them to death! ;) ;)

[nymapleguy607]

Very nice looking rig, I'll bet that thing will really chug through sap

[Sugarmaker]

DaveY
That is VERY impressive! I like the clean construction. Looks great with that steam a way in place too.
Thanks for posting these.
Regards,
Chris

[Dave Y]

Thanks for the complements. It is very easy to run. Almost as easy as oil! Brian what is ROI ?

[nas]

ROI = Return on Investment??

Nick

[Dave Y]

Thank you. I dont do well with initial speak. However the return on investment is much better that on a new 4x4.:)

[dschultz]

Dave Y
How many GPH is that rig suppose to do with a steamaway.

[Dave Y]

Well the numbers say 330, but we will see. What I like is the reduced wood consumption that the Force 5 offers. Then putting a steam away on it is like adding another 125gph with no more fuel consumption

[Amber Gold]

Dave, thanks for the pics. Nice looking rig. You have come a long ways in a short time and after talking to you in St. Albans, you have lots of future growth too. This started as a hobby for me, but it has switched gears to a business and now my goal is to make is very successful and provide a nice income on the side.

[Brent]

Hmmmm ..... if we .....
Hmmmm ..... or if ......

Happy Holidays to all.

[Ausable]

Yes , Guys I have come a long way In a short time. I have discovered I really cant have a hobby! Every thing I get in to becomes a for profit venture. How ever this is the best I have done on any of my Hobby attempts. More syrup does = more profit you just have to be patient on the profit!

Dave --- All I can think of to say is WOW! One of the most beautiful man-made things I have ever saw ------- Mike

[Dave Y]

I am glad everyone is enjoying the pics. This rig is not just a pretty face! It will work too.
Merry Christmas!

[nymapleguy607]

So I am getting ready to modify the over fire air in my arch and was wondering what size air holes did others use. My thought was to use 1/4" pipe plugs amd just drill out the centers to the size I wanted. I know the research paper says 3/8" holes, but to me that seems too big for a smaller arch. I thought 1/4"-5/16" holes and then space them apart every 4".
Thanks
Jeff

[Dave Y]

3/8 is the size you want. It will produce the volume of air you will need.

[Sugarmaker]

Air hole size? I am starting small around 3/16 inch dia and can open them to about 1/4 inch if needed. I have 30 ports around the firebox area.
Chris

[nymapleguy607]

Thanks for the replies
My thought was to use a threaded pipe plug and the be able to interchange the ends if they burnt out. I would have about 30 nozzles maybe a few more. Again thanks for the replies

[Brent]

Dave Y may be right that 3/8" is the size you need BUT

this is my minority opinion

- first there is no record that anyone anywhere ever tested how much air you need, what pressure it shoud be at and what the flow rate (volume in CFM ) should be.

I put a couple of 1-1/2" stainless pipes in my arch last year with a blower that put out 2 to 3 times the pressure of the Dayton blowers most guys are using. I put about 18 holes down each side, starting with really small and by the end of the season I had enlarged them up to nearly but not quite to 1/8". The more I openned them the better I like the results. But keep in mind the higher pressure blower. We could see the jets creating turbulence all the way to the center of the fire.

You can put in too much air. Once you hit enough to burn everything, any extra air just uses energy to heat the excess air, and it forces you good really hot stuff up the stack faster.

So, as I've said before, until we can measure the oxygen levels going up the stack, we're all just guessing. And I think we should be adjusting the air flow every time we fire. The Inteso-fire arches, which I think are the best on the market, have 3 separate adjustments so you can change tem on the fly.

I'm about to start on a new-to-me 8 2-1/2 that was a Leader Inferno. I've gone to an even higher pressure blower this year so I blast right to the core of the fire, with blasting in a huge volume.

I do like the idea of threaded nipples that you can replace. I did like the round tubes I had last year because I could turn them to aim the air up or down.

We've all got a lot to learn. I like keeping options open while we're experimenting.

[Ausable]

Brent --- I just have a home-made 2' x 5' evaporator without forced air. Yet - I enjoy reading about forced air rigs as I fired boilers for 12 years in Electric Generating Plants - so in somes ways the two things relate and in others very different. But - I have a few questions if you don't mind. Is there such a thing as having to hot a fire and boiling maple sap at to fast a rate? When boiling using forced air is temperature a concern at any point - other then stack temps and of course sap temps? Is there any concern for metal stress of fatigue from running to high temps? Have a lot more - but figure I should stop here -- Thanks Brent ---- Mike

[Brent]

Mike
I have never heard of having a fire too hot for sap. That doesn't mean it doesn't happen. It might be one of the things that affects nitre percipitation. Just don't know.

I can say that there is a point when the steel and iron in the evaporators suffer. From what I've heard, selling replacement grates is a good business. On the new-to-me evaporator that I'm rebuilding, it had been run so hot that all the galvanizing had broken down and the sheet metal sides were corroding badly. Even the angle iron frame was corroding and will be sand blasted in the rebuild. Interesting pattern on this. From the level of the grates up to pan and back under the flu pan. See photo.

I have to add that this rig was not well insulated. There was about 1/8" of ceramic and then firebrick. This is one of Leader's Inferno arches that has some modification to put air over the fire, but had no way to control how much went under the fire or over the fire. The guys I got it from said the steel roof of the sugar shack had a half inch of cinders on it at the end of the season. They were blowing tons of unburned gasses and solid stuff up the stack. They also had an unlimited amount of wood supply.

I am adding more controls and more stainless tubing for more air over the fire and we'll see how that goes.

I can't recall if it was in this thread but I found a fellow that has an identical rig to mine and he says he keeps the vari-speed on the blower turned down and runs great. But a friend of his has the same evaporator (Inferno ) and he runs it wide open and has to rebuild it every other year.

Yes you can get too hot for the structure. But I guess when you're starting to melt down and oxodize the evaporator, you must be making syrup at a hell of clip.
Trade-offs.

[WESTVIRGINIAMAPLER]

I have had an inferno arch for a few years and I don't think there is any way possible to run one too hot as to cause damage. It is stainless arch with steel rails and yes, the rails oxidize some which is normal. I run stack temps as high as 1800+ degrees aprox 8 to 9 feet from the firebox.

[Brent]

Brandon, Yea stainless is the way to go. I've been teasing myself with the idea of changing (building new) to stainless angle. With 1800 in the stack you must think you've got more wood than time to boil. I have to buy my wood so I'm going to run it more for efficiency than speed. Got an RO and Steamaway if I need to go faster.

[WESTVIRGINIAMAPLER]

I put new rails on mine when I tore it down to install AOF system this year. Yes, I have plenty of wood but hoping to make it a little more efficient this year, thus the reason for the AOF. I went with steel rails this year, never thought about stainless.

[Ausable]

Thanks for the reply - have another question - with a forced air system you have stack temps. that reach 1800F. Are the gases from the fire ignited all the way from the fire box - all along the arch and up the stack or is it just the heat of the exhaust gases that get temps of 1800F. Is there a limit on how long an arch can be when it is no longer efficient - example - say a 4' x 20' or can you just keep building them bigger - with a larger fire box and arch and more forced air? --- Mike

[Sugarmaker]

Over the weekend I installed the 2 inch PVC piping from outside the sugar house wall to the AOF system connections under the arch. About 15 feet of 2 inch. Still need to glue it up. Should have the blower installed by mid January and be ready for syrup season and or a test boil prior to first run.

Brent are you doing stainless sides on your arch rebuild?
Regards,
Chris

[WESTVIRGINIAMAPLER]

Thanks for the reply - have another question - with a forced air system you have stack temps. that reach 1800F. Are the gases from the fire ignited all the way from the fire box - all along the arch and up the stack or is it just the heat of the exhaust gases that get temps of 1800F. Is there a limit on how long an arch can be when it is no longer efficient - example - say a 4' x 20' or can you just keep building them bigger - with a larger fire box and arch and more forced air? --- Mike

I would guess it is just the heat as I never have had any fireball or re-ignition at the top of the stack.

[WESTVIRGINIAMAPLER]

Over the weekend I installed the 2 inch PVC piping from outside the sugar house wall to the AOF system connections under the arch. About 15 feet of 2 inch. Still need to glue it up. Should have the blower installed by mid January and be ready for syrup season and or a test boil prior to first run.

Brent are you doing stainless sides on your arch rebuild?
Regards,
Chris

Chris,

I just put 2 screws in each section of my 6" pvc air line and taped each section with HVAC aluminum tape so if I ever want to take it apart, it will be easy as it is not glued and I have no air leaks.

[twofer]

...

So, as I've said before, until we can measure the oxygen levels going up the stack, we're all just guessing. And I think we should be adjusting the air flow every time we fire. The Inteso-fire arches, which I think are the best on the market, have 3 separate adjustments so you can change tem on the fly.

...



Take this with a grain of salt because I haven't even set my evaporator up yet, but it is in. *fist pump* :)

My rudimentary plan to keep an eye on the air ratio was to jam a heavily cladded thermocouple between the syrup and flue pan. I would then dial in the evaporation rate with the primary air (under fire) and then gradually increase the secondary air (over fire) until I see a drop in combustion temperature and then dial it back a bit.

Also, from my understanding the secondary air can be as high as 40% in excess before you start to affect the combustion efficiency significantly. What happens at that point is the excess secondary air cools the combustion gases below what is needed for secondary combustion when it hits the fresh oxygen.

[Brent]

The guys that 'wrote the book' on this stuff say 20% of the air up through the grate and 80% over the fire. How you and I are supposed to get to that ratio is a challenge.

Some thoughts:
- if you have cinders and sparklers flying out the stack you've got too much air under the grates.

- if you've got black smoke your fire is cold, likely because you just threw in a bunch of nearly frozen wood and that kills the whole gassification thing. I'm not sure what to do with air flows at this time but I am going to put my wood in more frequently and in smaller piles in order not to chill the whole thing down too much. I'm guessing that when we fire, we should back off the air under the fire a bit, in hopes of heating the fresh wood faster and get the gassification going..... guessing.
Someone with an Intenso-fire or Force 5 would have some instructions that might help us on this.

- some guys here run stack temps at 1500 to 1800 degrees. That heat in the stack is doing nothing for us except global warming. If the air over fire is working correctly, almost all the combustion should be done long before the bottom of the stack. I know a fellow that burns oil. A couple years ago he upgraded to a Leader Maxi-flu. He did not change the oil burner set up at all, and he was thrilled to see his stack temps drop about 45 degrees - around the 850 mark. The pans were absorbing 45 degrees more heat with the larger surface area. He saw the difference in the oil bill at the end of the season and figured he more than paid for the new pan in year 1. Cutting, splitting, drying, moving and firing with wood eats up a lot of time. I want to burn every last bit of wood and wood gasses that I put into the arch.

[Sugarmaker]

Brandon.
I have my blower pipes for the WRU screwed together and the seam calked so I can take it apart. I am going to have several joints on the AOF with screws to allow dis-assembly of the pipes too. Plus I put in a pair of 2 inch plastic unions. Not moving very fast on things as it is cold in the sugar house.
Chris

Chris,

I just put 2 screws in each section of my 6" pvc air line and taped each section with HVAC aluminum tape so if I ever want to take it apart, it will be easy as it is not glued and I have no air leaks.

[nymapleguy607]

Worked on my AOF system last night. I got all the pieces cut to length and on set of holes drilled. Still need to tap them and the make my inserts. It is looking like 33 holes so far. 12 down each side of the firebox and 9 across the back manifold, but the number across the manifold may change. Also made a set of supports for under the side air tubes. Things are starting to come together nicely.

[Sugarmaker]

Jeff,
Be sure to post some pictures!
Chris

Worked on my AOF system last night. I got all the pieces cut to length and on set of holes drilled. Still need to tap them and the make my inserts. It is looking like 33 holes so far. 12 down each side of the firebox and 9 across the back manifold, but the number across the manifold may change. Also made a set of supports for under the side air tubes. Things are starting to come together nicely.

[nymapleguy607]

Well made some more progress last night. I finished drilling all the holes in the manifolds. It came out to 30 holes. 12 holes down each side and 6 across the back. I got about 16 holes tapped and then the tap broke, so I need to pick up another tomorrow. Instaled the hangers on the sides and got those leveled up. I still need to weld all the pieces together and build my dampers, but progress is being made.

[Sugarmaker]

Jeff,
I assume this is a in the bricks AOF system?
Blower type? and cfm? and location.
Tubing material type and size?
Controls on air flow?
Under air system?
Pictures:)?
Chris

[Sugarmaker]

Shots of AOF plumbing system to the blower. I have most of it glued but will have the upper and lower unions and a couple screws, as Brandon suggested, so I can take apart if needed.
Need the blower, wiring and switch to complete this project.

Chris

[murferd]

We got a "new to us" evaporator this season & I've been converting it from oil to wood & installing air over fire. A few pictures of my version of manifold. Do you think I need to cover the pipe?

[Dennis H.]

It would last langer if you did cover it with blanket.

How thick of wall pipe did you use. The thicker the more it could stand but wraping it would do more, just leave the tips of the nozzles sticking out.

[maple flats]

Ditto, it should be covered. Are you going to put firebrick in to protect the blanket? If not, it will suffer tearing and other physical damage. If firebricking over, continue right up to cover the manifolds with just the nozzles exposed. In time the nozzles will erode but not bank into the bricking (or blanket)

[WESTVIRGINIAMAPLER]

One thing that I see a little concern on some of the last few AOF designs on here is that they are right against the pans. I would think this would be a little detrimental, but I could be wrong. The research on this recommends 6" from the top of the arch. All the cool air going thru the pipes is going to keep them cooled and all that air is coming out right against the pans. I may be wrong, but just speculating. I would guess with the research that was done by UV, they probably tried several different combinations and found this worked the best.

After doing it nearly identical to the research paper including building the grate out of refractory cement, I realize these recent designs are cheaper and a ton less work and quicker and I hope they work as effectively. At this point, not sure how mine will work but it was designed as recommended.

[murferd]

I plan to brick the firebox area & up the slope 18 inches or so, looking for ideas on whether to cover the pipe with blanket or brick.
I hope that we have enough down angle the air won't affect the pan bottom area. Time will tell I guess.
Dennis where did you get your refractory? I think I would like to cover the blanket in some areas.

[Dennis H.]

I picked up my blanket at a local place that deal with pottery kiln supplies.
I never knew that they were there until I called a guy near by that does hand made pottery and asked him where he gets his kiln supplies. This place deals with all things pottery, clay, pottery wheels, glazing, and refractory.

The nice thing about dealing with a local guy is that you might not have to buy the entire roll. I didn't, just got what I needed. He would have cut me a deal if I bought the entire roll but I just couldn't think of anything to use it for.

[Brent]

Murray

In the pics it looks like your pipes are stainless. If they are I wouldn't bother with covering them. I had stainless pipes in mine last year and when they came out to ship it to its new owner, they were only slightly discoloured. They looked like they could take another 20 years.

[Sugarmaker]

Murry,
Wow when I looked at your pictures. It looks very familiar:)
Like Brandon says I hope these work near the pans. If It doesn't you will be cussing me!
Nice thing about yours is that you did not have to raise your pans.
But your nozzles will be about the same place as mine in relation to potentially "cooling" the pan.
First couple of boils should allow us to comment on this type of system
Looks like 1.75 I.D. stainless tubing? Whats the blower going to be?
Regards,
Chris

[MartinP]

Question for you guys with AOF. How big of blower (CFM) are you useing?

[nymapleguy607]

The blower on my 2x6 will put out 173CFM @ 5" static pressure and about 375 @ 1" static pressure. The key is make sure that the blower is a high pressure or regenative blower.

[Sugarmaker]

Martin
I will be using a 120 CFM SPA blower not sure of the static pressure.
Chris

[MartinP]

Thanks for the replies guys,
I currently have a line dryer from a milk house that I am going to try. Don't know if it will run for the amount of time that will be required but it came free with the milk veyor. Found a blower for 120 bucks that will work if this doesn't.

[Sugarmaker]

Just ordered the SPA blower (AquaPro, 2 hp, 110v) last night. If this AOF doesn't work out I guess I will have a blower for sale.:) Electricians coming tonight so things are coming together for a trial in the near future. Going to use a sliding reostat for the air control on the top blower. Not sure its needed just want another gadget to play with:) Plan to test fire the rig, boil some water, clean everything up and be ready for the season to begin. Time to stop playing with equipement and boil some sap!

Chris

[WESTVIRGINIAMAPLER]

Here is blower I installed, it is pushing 559 cfm at 4" of static pressure.

http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=7c447&op=search&Ntt=7c447&N=0&sst=subset

[maple flats]

WVM, that should be a good match for your rig. I'll bet mine is close but slightly less CFM, and it works GREAT. There are no specs available for my 75-100 yr old HP blower. My observations are that the pressure accounts for more than the volumn. I base this on the fact that I feed with one 4" PVC pipe from the blower to a Y and thru 2 ball valves, 1 each under fire and over fire. I seem to get the best action with the valves about 30-40% open under fire and 60-70% open over fire. This works better than fully open over and under 30% open under. This might relate to the pressure. I suspect the pressure/volumn relationship is best there. With both fully open the pressure would most likely be less.

[Brent]

Brandon

I've just in the last few days learned that there is a very serious difference in that blower and the ones the Leader put in thier Inferno arches. It's the motor.

If you want to run it through a rehostat so you can change the speed, you need one with a shaded pole motor. Shaded pole motors do not have capacitors and are not available in dual voltage (110-220). I was wanting to put rehostats on my Gast vac pumps and was searching around for data on rehostats and various links let me to this gem of info ... before I ruined a motor.

Check it out. The info I picked up looked valid but I'm no expert on single phase motors.

[Sugarmaker]

Nic wired in the sliding reostat switch and ran the MC cable for the new blower tonight. So one step closer to being ready.
Chris

[WESTVIRGINIAMAPLER]

I done away with the Rheostat and my air under the fire and over the fire is controlled by dampers that are on the right side of the arch next to the fire door and I hope to find the optimal setting for above and under air and leave it set all day and not have to change it while boiling.

I have a 6" pvc pipe supplying the air to the firebox from the high pressure blower and the underneath and over air are both supplied from this 6" pvc pipe. I have about 30' of pipe and blower is outside above wood storage.

[Sugarmaker]

My blower/s will not hold a candle to Brandons, and not sure if the dimmer will work yet we will see. (not sure any of it will work yet:))
But I have a question. I am close to having two blowers the same except for the HP currently the 1.5 hp is on the WRU and I was going to put the 2 Hp on the AOF. Where do you think I would get the most good? Should I put the 2 hp on the WRU (Water Reduction Unit) to try and get more sap bubbling action? Seems that might be a better use of the additional cfm's?
Chris

[WESTVIRGINIAMAPLER]

Chris,

The motor on my blower is only 1HP, but it turns at 3450 rpms. Sounds like a lot of HP for not a lot of air??

[Brent]

Here's something that you guys should find real helpful.

This link will get you a pdf file of tables for airflow through an orifice at different pressures.

So you can look at furnace type blowers vs radial blowers
vs regenerative blowers, hole sizes and how many cfms you can actually get into the arch.

http://www.duffyslanemaple.ca/syrup-equipment/AirFlowOrifice-1.pdf

[maple flats]

Some of you need to realize just how much pressure we are talking about for high pressure air. Even though it is called high pressure, the numbers in reality are quite small. For example, if we have 4" WC (4" water column) you only have just over .14 PSI. The basic point is that a squirrel cage blower can't generate even this small amount of pressure, but they do move lots of air. But that little pressure creates the turbulance needed to make the gasses burn well.

[Sugarmaker]

Trying to get some specs on the spa blower so I can compare.
Back to the question which blower in which location? any comments?
Chris

[Brent]

Here's the blowers that Leader put on my rig

First for the Inferno arch. As I understand it, the early models had all the air under the fire. Mine was modified later to put air through the door and door frame. The original blower for the 2-1/2 x 8 rig was a Dayton4C054B with 1/3 hp shaded pole motor. The spec says it should output 940 cfm with nearly no back pressure, ie at 0.1" SP.
But it drops down to only 210 cfm with max pressure at only 0.8" SP.

For the Leader Steamaway, they change to a high pressure radial blower. Dayton 2C820 which will deliver
270 cfm at 4" SP.

So the change to radial blower delivers 28% more cfms at 5 times the pressure. It needs the pressure to bubble up under the head pressure of the sap in the Steamaway.

So back to the air over fire. Play with your planned rig and all the holes and diameter with the tables noted a couple posts above this, then figure what blower you want. My experience last year with a radial high pressure blower leads me to think you can use a lot less air if you inject almost all of it above the fire through smaller hose to make more penetrating high pressure jets. But like most of us, I've only played with one rig. This year with the new-to-me modified and now re-modified 2-1/2 x 8
will be interesting.

[WESTVIRGINIAMAPLER]

Here's Brent's blower with motor and specs:

http://www.grainger.com/Grainger/DAYTON-Blower-7D749

[nymapleguy607]

I have the exact same blower as brents. As for Sugarmakers original question I think I would try each blower on your AOF and your WRU, and see which one worked better. Problt easier said than done though. But that would be my thought.

[xulgiy]

I made 275gal oil tank arch a few years ago, and put in an over the fire manifold last year. I never got enough air to it with the blower I used....so out it came! What I did do was use fire brick for the fire box, and drilled 3/4" holes for grates. I then cut the back out of the tank just enough to slide a big furnace blower in the air space underneath. This gave me a planum and a ton of under air which me the unit boil like like crazy and eat wood at the same rate! So what I'm wondering is this. If I drill holes in the brick, across the ramp, toward the top and blow air toward the front, if that would help with my wood consumption??? Any thoughts?

[nymapleguy607]

I made 275gal oil tank arch a few years ago, and put in an over the fire manifold last year. I never got enough air to it with the blower I used....so out it came! What I did do was use fire brick for the fire box, and drilled 3/4" holes for grates. I then cut the back out of the tank just enough to slide a big furnace blower in the air space underneath. This gave me a planum and a ton of under air which me the unit boil like like crazy and eat wood at the same rate! So what I'm wondering is this. If I drill holes in the brick, across the ramp, toward the top and blow air toward the front, if that would help with my wood consumption??? Any thoughts?

It might help some, if you read some of the posts from the begining of this thread you will get a better idea about how over fire air works and how it needs to be setup to work.

[xulgiy]

I do indeed have all of the info, and built everything to specs....except for the expensive blower. I'm just trying to make things work without dishing out a done of cash.

[nymapleguy607]

If you want something that will put out higher pressure air than the furnace blower and don't want to spend alot you could use a leaf blower. I did that last year before I bought my new blower and that helped some. A furnace blower really doesnt have the pressure needed to remix the unburnt gases.

[murferd]

This is the blower I got off Ebay for my setup, probably too large but should be able to control with the valves. Hopefully!
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=320635554177&ssPageName=STRK:MEWNX:IT

[maple flats]

To answer your questions, I would use the higher pressure blower over, to create a "boil" and the lower for combustion. However, high pressure is very important for over fire air. With high pressure air on top, aimed down at the right angle and all around the inside of the firebox, you create a turbulance that burns the wood gasses far more completely, gases that would have gone up the chimney unburnt to ignite at the top of the stack when they got some air.. Only under fire air significantly increases wood conumption. That is why I use my balancing valves to direct most but not all of my air over the fire. Doing this increased my evap rate while using LESS wood. Infact, I used to need to add wood every 5 minutes, now I add every 12-15 and only add slightly more than I did on the 5 minute rate before. Boil faster and use less wood, I think it is a real good combination.

[Sugarmaker]

Thanks guys for the information. Yes some trials in the future.
Regards,
Chris

[Brent]

Dave, I'd like to buy you a drink some day.

[Sugarmaker]

Murry,
I would try that blower, looks like a good unit.
SM

[twofer]

Well the Inferno I ordered finally came in and now I can participate in the thread. While it is an Inferno I had Leader remove all the air delivery equipment that comes with an Inferno. Essentially I just wanted the arch and the air tight front. Here are couple pics of the air over fire manifold.

http://www.wilsonsugarhouse.com/images/external/airOverFire/leftSideAir.jpg

http://www.wilsonsugarhouse.com/images/external/airOverFire/rightSideAir.jpg

Next up I plan on getting the arch set and get to work on casting the refractory floor for the primary combustion air (air under fire).

[WESTVIRGINIAMAPLER]

Where exactly are these air over fire nozzles located on the arch?? Looks different than mine but mine is 8 years old.

[twofer]

They are located six inches down from the top of the firebox and they start at the door and run back to where the ramp starts.

[maple flats]

Dave, I'd like to buy you a drink some day.
Brent, I rarely drink but I'd love to sit and chat anytime.

[maple flats]

Twofer, Looks like a good job. I will sometime cast a floor using the specs in the original report, I have the refractory, but for now I am still using the original grates. Some summer soon I will do it.
My manifold looked very similar on each side but I wraped around the front for 1 nozzel each side of the door facing rearward and also across the rear facing forward, all angled down at the prescribed angle. I guarantee you will not regret taking the time to do this. Your cumbustion efficiency will rise considerably and wood consumption will drop while boiling faster and more evenly.

[maple flats]

Last year I could not boil at full speed because the flue pan (which starts just 2' back) would boil so hard sap jumped all over and lots jumped from the flue pan into the gasket between the pans and into the syrup pan. This year I made a shield like what Leader has to eliminate this and send the jumping back into the flue pan. Now I expect to be able to boil even faster.

[WESTVIRGINIAMAPLER]

They are located six inches down from the top of the firebox and they start at the door and run back to where the ramp starts.

Are these installed from the factory or did you put them in??

[WESTVIRGINIAMAPLER]

Dave,

I built a refractory poured grate nearly exactly per the research paper and will let you know how it performs. I have the holes alternated in every row to increase sufficiency with about 12 holes per square foot.

[nymapleguy607]

Made good progress on my AOF system this weekend. I still need to connect the under fire air to the damper box and maybe reduce the opening there. I got my blower powered up and connected to the damper box. I need to warm up the garage enough so I can caulk around where the AOF manifold comes through the bottom of the arch. I must say the inside of the firebox looks like a hybrid of an intenso-fire and a force 5. Will try to post some pictures to night.

[ABS5405]

Dave did you preheat incoming over fire air? Or just get it in the right place towards the fire.
Any body have experience with preheating the air too? Seems like they are doing that with the Force 5. They must have a reason for it.

[maple flats]

I did not preheat the air, but I'd think it would be rather warm by the time it gets out the nozzles. The manifold is 2" sq tubing and that is only protected by about 3/4"-1" refractory. The mainfold would get quite warm and thus the air would take up some of it. My manifold just goes up into the ramp space and distributes around the firebox from there. It might help some if you ran the infeed air thru the arch under the flue pan it might add some pre-heating to the air. I don't know how much that would help, mine works fantastically but I suppose there could be fantastic+.

[nymapleguy607]

Well I hit a small road block with the AOF. I tried reducing the opening for my under fire air but I'm still getting alot of air blowing by the damper and the baffle. I think tonight I will add a deflector ahead of the blower opening to force the air up as it comes in. Knowing what I know now I would have made the blower connect at the top rather than the bottom. Oh well hind sight is 20 20. I keep forgeting to take pictures maybe after I get the air distribution figured out.

[twofer]

Are these installed from the factory or did you put them in??

I had them put in after I received the arch.

When you poured the refractory grate did you use any stainless steel needles for reinforcement? Also, do you have any supports under the refractory grate?

I'm trying to figure out if I need to run a support underneath the floor or if it will be strong to span the 2' without it.