Need idea's on raised flue setup

[1/2 pint sugarhouse]

I just bought a small brothers 2x6 raised flue and sold my 1/2 pint. I have some high hopes, but not real sure about how to set up the back of the arch.
I have been told different things. Some say to fill the back with k-wool or bricks so it forces all the flue gases into the flues. Another idea was to stand up a few bricks to create a wall to make turbulance, also to make several different walls for more turbulance. I need more input on what more people have done or what has worked best for them. Thanks for the help, Scott

[Fred Henderson]

I don't have a raised flue but I have heard tell to have the flues touch the blanket.

[SBClorite]

Do you use a blower, or ever plan to?
I would think you want to leave enough clearance that it would not impede your draft/slow your burning (assuming you burn wood).
We have a blower and we have an inch +/- below our drop flue pan.

[325abn]

On my raised flue I have blanket just about up to the bottom of the pan so the heat is forced up into the flues. It takes some tweeking to get it set up right so the gasses are forced up and into the flues yet have a good route to escape the arch. For the most part I have less than a 1/4 inch between the bottom of the flues and the blanket.

[1/2 pint sugarhouse]

SB Clorite, I do not have a blower, I'm not sure I want to spend any more money this year. I assume it would probably matter how much space is left if there is a blower added?

Thanks, Scott

[1/2 pint sugarhouse]

325abn,
I'm wondering how you tweek it after the pans are full of sap? also how much space do you leave at the end of the blanket when the gases leave the flues?

Thanks ,Scott

[VT maple maker]

On my small brothers 2x6 i have the brick layed flat in the back part of the arch. When i test boiled it my flue pan was still boiling away like crazy! Im not sure how small brothers built there arches but the one i have was custom made by the original owner of this rig. He bought the pans and built the arch. The fire box is normal size for a 2x6 but it arches right up to the bottom of the flue pan at the back of the fire box. Behinde that it drops down about 4 inches the rest of the way to the stack. With the brick in there id say there is a little better than 2 inches or so to the bottom of my flues. Im sure it would be more efficient if i made it less than that but for this year its what i have to go with. I was still very impressed at the boil i had going in the pan with the brick layed flat. Good Luck!!


Kyle

[maple flats]

For my raised flue I have the bricks at the rear of the firebox straight up to within about 6" from the flue bottoms, then it tapers up at about 35 degrees up to within about 1/4" below the flues and stays there back to about 6" before the stack where it drops down about 6" to give good draft flow up the stack. It works good for me. Under the raised section I filled it with vermiculite and capped it with flat brick with minimal refractory.

[SBClorite]

Scott,
It would stand to reason that a blower would need a little more room for air to flow, since you are adding more air, which burns more wood, which produces more combustion gases.
My brother works in HVAC and is working on a degree in mechanical engineering (he turned out a lot smarter than I thought he would!). I have posed the question of "how much space" to him, via email. He is usually a good source of info and I'm sure his answer will help.
I'll let you know what we come up with, in case you want to add a blower down the line (a reclaimed furnace blower works well, which my brother usually can find for me free).
Thanks for asking this question. We will be working on the same problem as we build my arch after this season. It is better for me to think of these things now :)
Steve

[Brent]

last two years we ran a Half Pint.

I got a blower from a local Home Depot style store with a rheostat built in for about $80.

When we got it going, in the dark, the entire stack was glowing a dull cherry red.

We just eyeball engineered the air by turning the blower speed up and down. Since the Half Pint is a long way from airtight, blow back out the front was what set the limit. We figure the Half Pint went from maybe 5 GPH to about 8 GPH with the blower. We needed all the help we could get, on the back porch, in the wind and the dark.

[Father & Son]

I just went from a drop flue to a raised flue this year. It's a 2 x 8 Dallaire. I was told by the local Maple Pro dealer that you have to build a ramp to direct the flames into the flue pan. He said determining where the ramp is placed is the most important thing. He said the flame must be directed into the first 1/3 of the flue pan. My flue pan is 5' (60") so the ramp ends 20" back on the flue pan. Coming back down into the arch he said can be an opening 8"-12" in size to allow the gases to exit through the stack. He said to try 10" and see if you get good draft, too much draft - close the opening a little, too little draft make the opening bigger. I know nothing about this other than these are the guidelines he gave me to start with. If this is incorrect, someone please correct me. The void area I filled with vermiculite and covered with ceramic blanket.
I tried to put together a quick drawing (I'm no artist) to illustrate this. I hope it helps.

Jim

[Brent]

I got to wonder why "we" have to build ramps and fill voids. Shouldn't the arch make be designing that in ???

[Father & Son]

You would think the arch would be made for the design but there must be a good reason. !!!!!!!!!!!!!!MONEY!!!!!!!!!!!!!

Jim

[danno]

I got to wonder why "we" have to build ramps and fill voids. Shouldn't the arch make be designing that in ???

I asked the same question a couple of months ago - and received a good answer. The arches are made to accomodate raised and drop flue pans.

[Brent]

I asked the same question a couple of months ago - and received a good answer. The arches are made to accomodate raised and drop flue pans.

Now isn't that the height of stupidity.

Maybe they should leave the flues too out and let us make our own depending on whether you want a raised or drop flue.

The real cost of making a shallow arch for raised flue or deep arch for drop flue is so close to the same you could simple say
"you want drop flue, OK two hundered bucks more"

Instead we screw around with unscientific experiments where you and I play dam builders will plasma gases and little or now way to accurately measure
real differences in performance. We could be busting a gut to split an extra cord of wood or paying for oil ... for what???

Isn't there a responsible builder out there ??

[super sappy]

Just wait until china starts building all of our stuff, We will get instructions in 7 languages that are difficult to follow and half of the parts will be missing lol. ...-To answer your question Jim I just got a new maole pro as well and this is how they had me set it up.(Tim in St Albans) Your drawing is correct. This is what my dealer drew out for me. The front ramp 1/3 back. As tight to the bottoms of the flu as you can. Then fill with kitty litter or sand etc. He said to scallop this out a little "sand" then the opening of the rear ramp should be the same as the debth of the base stack and tight to the bottom of the pan again. So on my 2x6 my base stack was 6" deep X18" +- so the rear opening was 6" from the Base stack plate to the top of the finished rear ramp. I did a test boil and she was tossing water over the sides of the pan back there. I know that alot of guys do it different but it really ripped. I guess that scallop in the "sand " will cause some added turbulance. I hope this helps.-ss

[PATheron]

Father and son- I hired a guy to brick my arch becouse I was up against it on time and I dont like masonry work. He did a great job and called and asked a lot of questions to get it right. When I boil you can almost put your hand on my stack and it boils hard. If you want Ill pm you his number if you want to call him and ask him some questions. Guy is a very nice guy and im sure he would help you out. Theron

[ibby458]

When I bricked my arch, I calculated the stack collar area, and tried to maintain the same number of square inches as the gases enter and leave the raised flues. That worked out to be about 6" back from each end. (THe back of the firebox wall ends 6" back from the front edge of the flue pan, and the "dropdown" into the stack began 6" from the back of the pan).

To avoid cutting so many bricks, I ended up with a 2-1'2" space under the pan the rest of the way. It worked, but not well. There was so much draft, the fire really didn't go up into the flues, just ran underneath. The sap boiled like CRAZY at the beginning and end of the pans, but only margainally thru the rest of the pan.

Even with a tight hood and super-preheater, I could only barely reach the rated boil rate for the evaporator with a lot of extra tinkering. After reading a lot of posts here and discussions with other sugarmakers, I'm installing another layer of brick under the flue pan, leaving only 1/4" of extra space under the flues. The fire will HAVE to stay up in the flues this year.

This will obviously cut back on my draft, so I'm installing a blower to help it out. My doors are warped and cracked, so that will also limit how fast I can put the air to it. We'll have to see how this works out.

[maple maniac65]

I have a 30x8 Leader Revolution drop flue. No instructions came with it on how to insulate the arch so this is what I did.

1. Cut 1" arch board and fit it in on all sides.

2. Used full brick except for last course which was 1/2 brick.

3. Ran 1" ceramic blanket under flues and over ramp to back of where the wood lies.

4. Decided there needed to be more insulation on ramp so ran another piece on ramp making it 2" thick.

Resulting fact is a 30x8 with 2.5% sap now does 100 gallons/hour. Have now added a steamaway and that is supposed to increase production 75%. I am looking forward to finding out this season.

Yes, I do have a blower and a extreme back pressure on fire side of the flues. I generally see 1400 on my stack. Leader reps say I am wasting wood but I normally make 35 gallons /cord of wood.

There are no set standards on how one should run their sugaring equipment. I for one run it to the extreme and try to get the most out of my time when I am boiling.

[Russell Lampron]

Ibby take the fire brick out from under the flue pan, fill the area with vermiculite to 2" below the rail and put the brick back on top of that. Normally you don't have to use any brick past the ramp that goes up to the flue pan but you already have them so use them.

Russ

[super sappy]

Theron- I thought that I was nuts with such a low stack temp. My back pan was boiling like crazy and the stack temp was low, like 450 or so .My little 2x4 ran a hotter stack temp than that. I have alwayse been told to have a stack temp of at least 600. I dont know I guess if it aint broke dont try to fix it. -I really wanted to use the vermiculite in the back but it was not readyally available, so I used kitty litter / floor dryer. I thought that it may absorb any moisture that could condense back there. and I had a 50 lb bag on hand. Can anyone think of a downside to using this stuff? -ss

[Russell Lampron]

SS,

The downside to using kitty litter is the same as sand. It will hold the moisture and cause the metal under it to corrode. Vermiculite won't hold moisture.

Russ

[SBClorite]

Brent,
When have any of us left things the way the factory sent them? I agree a controled factory setting would be good to have, or at least some instruction on how to maximize effieciency, but most people would change it anyway.
We are always trying to get more out of the machine than what it is rated for.
That's why it's great to read these posts. You can pick the best option for your budget and equipment.
I still haven't heard how much extra draft a blower needs. Hopefully someone here can give us a good idea.

[Brent]

Steve
Being a diddler I would certainly rather have the floor of the flue too low than too high. It can be built up pretty easily. But I have seen some new stuff that had 14" of gap between the floor and the flues.

Anyway playing with bricks or blanket and getting a variable speed blower and a stack thermometer will get us close.

[SBClorite]

Super Sappy,
A possible reason for a low stack temp could be the way you are measuring it. When we first got our 3x12 at work we had low temps until we made sure the stem of the thermometer was deep into the flue pipe.
I guess the outer column of gases is a much lower temp than the center. If you have a large diameter pipe, the hottest gases are in the center and a short thermometer (or surface type) won't give you the best reading.
So, if you increased your flue size, but used the same thermometer, you might read a lower temp.
We actually melted the solder on our roof boot trying to get a higher temp in our first year. (we also had the pipe slip down, so there was a lot of heat blowing on the boot). That's when we realized that we needed a longer stem on the thermometer and now we read around 1000 when it's really going.

[peacemaker]

i agree with sbc .. i had a friend who raced moto cross i almost fell over laughing when his sponsor sent him his new bike him and his dad started tossing parts left and right mumbling them factory boys no nothing ...
i was rolling and teasing them ...lol then one day he was in my millwork shop to see our new molder he looks at at and see all the parts me and dad remade and asked whats this .. to which i reply them factory engineers dont know anything about making molding ...lol

[peacemaker]

hey brent did your new rig come yet ?

[Brent]

Patrick is leaving Quebec Monday with 4 rigs on his truck. I'll see him when he gets the first 2 set up. Hopefully by Wed or Thursday.

[ibby458]

Russ - I agree about vermiculite. Wish I had done it that way from the start. Since I didn't, it's cheaper to buy the extra 18 bricks I need. When I was first planning this, I priced ceramic blanket - MUCH cheaper to brick it.

I'm still thinking that I'll build the perfect arch from scratch when I build my new sugarhouse, to correct all the mistakes I made the first time around.

My stack thermometer stem does hit the center of the pipe, and when I'm really pouring the wood to it, it'll stay at 1000 to 1200 degrees, but my flue pan still isn't boiling hard down the middle. Hope to change that this year.

[Brent]

I've seen it mentioned here that the big advantage to not using bricks is that the lighter insulations, vermiculite, blankets or boards, will loose there heat heat fast when you're shutting down. Less risk of boiling dry. I guess the inverse is also true, faster startup.