2x10 evaporator with 8' flue pan, wierd size, will it work?

[motowbrowne]

I'm looking at finding a used evaporator in Wisconsin. I have a couple of leads, but mostly they are old and lead soldered, which I would like to avoid. I did find one, a 2x10 that is 13 years old and only the syrup pan is soldered, while the flue pan is welded. I figure even if the syrup pan is lead soldered, replacing that would be a lot cheaper than replacing a both pans on say a 30x10 or a 3x10, which seem to be the other options available. I must admit that the 30x10 and the 3x10 seem like more regular sizes, especially since the syrup pan on the 2x10 is only 2x2, which seems tiny. I'm worried that the small syrup pan won't be able to keep up with the flue pan, and I'll get sugar sands in the flue pan and have to deal with cleaning that out in the middle of the season. I am in no great hurry, and I will keep my eyes open for something between a 30x8 and a 3x10 with lead-free solder or welded pans, but I would like to know if anyone out there has used a setup like this with a huge flue pan and a small syrup pan. I also want to say thanks for all the great info I've already found on this forum.

Ryan in Wisconsin

[Bucket Head]

Ryan,

I'm trying to figure out a ratio of minimun syrup pan to maximum fluepan also. I asked that question before and did not get any feedback. I'm hoping that some folks will chime in and share their thoughts. At some point a syrup pan would be too small, I just don't know at what point. I have an odd sized rig also. I could certainly use more flue pan for the fire I can burn in it. I just don't know what type pan or size to shoot for.

I think your 2x10 w/2x2 front pan would be o.k. Chances are your firebox/fire won't be able to fully boil the rearmost portion of the flue pan. It will still evaporate sap, don't get me wrong, but your actual performance will likely be very similar to a 2x8. Whatever additional evaporation the last two feet provide probably won't have too much effect on the front pan. I would go with that if I had a chance to get that size rig. I would'nt worry about the nitre build-up in the back. It would'nt be much and whatever does end up there is easier to clean out than the front pan. The cleaners for both soldered and welded pans works well.

I agree that a front pan would be easier to finance if you opt to have a new one made. It will also be easier to have a 3x2 front pan made and stretch the arch if at sometime you feel more syrup pan is needed.

Steve

[3rdgen.maple]

I wouldnt be too all concerned with niter/sugar sand in the flue pan either. Now Niter in the syrup pan might be a different story. If you go with this rig you might want to consider getting the new syrup pan you want and keep the old one to swap out in mid boils so you can keep boiling while cleaning out the other syrup pan if you have alot of build up. I think the only other thing is you would be drawing off more often than norm with the 2 footer on the front. Not that is a bad thing. Is this a drop or raised flue pan? Couple other things come to mind would be to make sure than thing is perfectly level from front to back and side to side. The other thing is Brandon brings up a decent point that if you judge it based on a 2x8 and expect no more than that out of if then who really cares what the back 2 feet of the pan is doing right. If you were having a pan made to fit a 2x10 arch and expect higher gph than you would be wasting the money you paid to have it made. Since its a good price what the heck. Another note I m thinking here is a 2 foot pan on that arch might just be the perfect fit for it. Since its so long and most of your heats up front I think having most of it a flue pan would get the most out of that flue pan with the 2 foot syrup pan. Now heres where the kicker is in my mind, what happens if you want to put a preheater on it or a hood or maybe a steamaway in the future.Its going to cost you more money to have that stuff custom made to fit a 2x8 flue pan. I think you said you were looking at no more than 600 taps once? I would think anything in the 2x8 or larger range will do you good. Preferably a 30"x8' or larger. Just some more thoughts for you to ponder.

[sapman]

I wouldn't think the syrup pan has any lead solder in it. Unless it's not made by a reputable company. My first evaporator was made in '91 by Leader, and was all lead-free solder.

[wiam]

I do not believe there would be any more nitre in that 2x2 pan with raw sap than there is in mine on a 2x6 boiling 10%.

William

[PerryW]

I do not believe there would be any more nitre in that 2x2 pan with raw sap than there is in mine on a 2x6 boiling 10%.

William

that's what I was thinking. A typical evaporator running concentrate would have far sweeter sap running into the front pan than a 2x10 w/ a 2x2 front pan.

[motowbrowne]

Okay, thanks you guys for all the suggestions. I am definitely leaning toward this evaporator because of the fact that the flue pan is welded, my only concern was the weird size flue pan. As far as other options are concerned, this one is closest to the size that I would like (I think a 30x8 would be ideal, and this one is actually the same size, just weird dimensions) and the other ones are all a little large, my next option being a 30x10. Well, I will keep you posted as to which one I go with. I am curious about wha someone mentioned about levelness, do you mean the levelness of installation, or just making sure that the pans are both square and not warped? Thanks for all your help.

Ryan

[WESTVIRGINIAMAPLER]

2x10 would be 25% more efficient than the 30x8.

[RileySugarbush]

I totally agree with Brandon. Long and skinny is the way to go if you have good draft/combustion air.

You will have some great options:


Super efficient if you fire it slowly with the back of the long flue pan acting like a fantastic preheater that can actually evaporate some water.Pulling most of the heat out of the flue gasses.

Super high rate of you crank up the under fire combustion air. High stack temps and low fuel efficiency.


If I was designing an arch from scratch this is what I would base it on, with good insulation and air under and over.

[3rdgen.maple]

2x10 would be 25% more efficient than the 30x8.

Please explain. the way I see it you need a firebox big enough to feed a 10foot pan. If you dont have the fire how is it more efficient? Seems to me if that is the case then why is it an odd ball size and not the norm?

[WESTVIRGINIAMAPLER]

If I had it to do over knowing 10 years ago what I know now I would have had a 2x12 evaporator built with a 9' flue pan and could have easily gotten 100+ gph out of it. I run stack temps of 1300 to 1500 and sometimes pushing 1700 degrees aprox 3' up the stack past the end of the flue pan. This is wasted heat I could put to good use with another 4' on the end of the evaporator.

[motowbrowne]

That's kinda what I thought too about the wasted heat. In my mind a high stack temp. is just heat gone up the chimney. Even if the last 3 feet of the flue pan doesn't boil, it is still sucking heat out of the arch before is goes up in smoke. So it does beg the question then, why are narrow long arches not the norm? Although, to partially answer my question, I suppose they sort of are, that's why don't see any 6x6 evaporators.

[RileySugarbush]

Each foot of firebox width in a 4x12 feeds a 1foot wide by 12 foot long strip of evaporator. There is no need to make it 4 feet wide. A 2 foot wide firebox is capable of boiling a 2x12 just as well.

Now a typical 2x6 has a pretty shallow firebox, about 2 feet or less. Mine is only about 18 inches front to back inside the bricks. If I really wanted more BTU's generated, i could make the firebox deeper so the fire would be bigger in terms of square foot of combustion. This is typically done on big evaporators like the 4x12. You can toss in long logs.

But with the improvements in combustion air there is no need to have a huge firebox. As Brandon and motobrowne mentioned, we now have plenty of heat out of a small firebox. Long and skinny with lots of flue area is what I would go for

[brookledge]

When I went from a 3X8 to a 3X12 it burned the same amount of wood but saw my evap rate double. As far as continueing making them longer I suppose it gets to the point where the cost in materials(stainless) out weighs the production
Keith

[PerryW]

That's kinda what I thought too about the wasted heat. In my mind a high stack temp. is just heat gone up the chimney. Even if the last 3 feet of the flue pan doesn't boil, it is still sucking heat out of the arch before is goes up in smoke. So it does beg the question then, why are narrow long arches not the norm? Although, to partially answer my question, I suppose they sort of are, that's why don't see any 6x6 evaporators.

I think long, skinny evaporators are probably more efficient, but I don't think the relationship is linear. A short evaporator is designed with a shorter firebox (shorter wood) and a smaller diameter stack than a longer evaporator with the same width and should use less wood per hour. The ramp (in a raised flue) would also begin sooner in a shorter evaporator.

I think the bottom line is that as long as your stack temp is not too high, you are not wasting heat. A properly design 3x8 evaporator should have the same stack temperature as a properly designed 3x12.

[WESTVIRGINIAMAPLER]

I can run my evaporator at about 45 gph and keep stack temps at 1000 or less or I can run it around 65 gph and run stack temps of 1300 to 1700. Yes, higher stack temps use a lot more wood but in the long run there is not much difference due to fact that I am gaining about 35% more in gph. I would rather run it at higher gph and get done boiling lot sooner or on days I have an open house and don't want any sparks flying out I can run under air shut down and mainly just AOF. If I really wanted to make it ultra efficient I can run it with a steamaway next year and just AOF and get around 70 to 75 gph and probably make 30+ gallons of syrup with 1 cord of wood.

[motowbrowne]

I was wondering about the air over fire concept. Our woodstove int the house has a couple of tubes with holes that feed preheated air into the firebox. My understanding of AOF in maple syrup is that it's essentially the same concept. My question is whether I can retrofit something into the arch that would allow me to add hot air. I guess I'm thinking of a pipe or two that enter the arch at the back under the stack and then runs up to the backside of the firebox. Is there an easy way to add an AOF setup to a manufactured arch? I'm sure that there's a bunch of good info on this site, but I just thought I'd ask while we were on the topic.

Thanks,
Ryan

[RileySugarbush]

I added a new AOF to my existing arch this year. It worked great.

I didn't preheat the air, but attached the inlet to a manifold at the top of the back firebox wall from underneath the flue. I made the manifold in a u shape to reach the front of the firebox along each side and dropped it right in on top of the firebrick. I wrapped it in ceramic blanket and poked the nozzles through.

You can get a look at it on You Tube before it was installed at:


http://www.youtube.com/watch?v=LhiEyMjVx5g

And watch it in action at:

http://www.youtube.com/watch?v=p3Y8pc530LU&feature=youtu.be&hd=1

[WESTVIRGINIAMAPLER]

My manifolds get hot enough that the air gets heated good in them and it is pretty hot coming out of them.

[brookledge]

As far as efficiency it comes down to how you want to run it. just like a car, you can go easy on the gas pedal and get better mileage and take longer to get to where you want to go. Or put the pedal down and burn more fuel but get there fast. If it wasn;t for speed limits everyone would opt for getting there fast.
just like my evaporator. I'd rather boil as fast as I can even though I have higher stack temps and i'm burning more wood than if I eased it back a little
Keith

[motowbrowne]

Speed limits aren't the only reason to slow down. I don't think I'm the only one who would like to burn as little gas as possible, especially with gas over four dollars a gallon. I drive an eighty-three toyota tercel, and if I go sixty on the highway I can get close to forty mpg. One of these years we may have six hundred taps or more and then I'm sure I'll want to put the pedal to the metal, but in the meantime while the evaporate is still oversized, I'd like to know more about operating for max efficiency. By adding AOF is it possible to even achieve both, faster rate of evaporation and less fuel consumption?

[RileySugarbush]

Certainly adding air over fire can improve fuel efficiency. The idea is to get more complete combustion of the fuel gasses right above the fuel instead of at the top of the stack. After that it is a balancing act, where air under the wood will increase the rate that those gasses are given off.

For max fuel efficiency, minimize air under and adjust air over for a reasonable stack temp.

[motowbrowne]

The high efficiency wood-stove we have for heat doesn't have any type of blower for the air over fire pipes. We don't have power in the sugar bush, and I kinda like it that way, so I'm wondering if I could rig up something similar in my arch. Essentially try to get the doors as airtight as possible and let the fire do the work of moving the air into the manifold and the back of the box. Does anyone know anything about that? I've been reading some air over fire threads, but they seem to be mostly about what kind of blower to use.

[Dill]

I've been trying to read the AOF thread, but honestly its just too long.
Could we get a how to thread for retrofitting into an existing arch that wasn't 60 pages.

[RileySugarbush]

The high efficiency wood-stove we have for heat doesn't have any type of blower for the air over fire pipes. We don't have power in the sugar bush, and I kinda like it that way, so I'm wondering if I could rig up something similar in my arch. Essentially try to get the doors as airtight as possible and let the fire do the work of moving the air into the manifold and the back of the box. Does anyone know anything about that? I've been reading some air over fire threads, but they seem to be mostly about what kind of blower to use.

You could try it but don't expect too much. The key isn't just getting some air over the fire but violently mixing the air into the combustion contents. To do that, the air needs to be really squirting in there. In my setup, the air is exiting 16 nozzles at 180 inches/second.

Just to give a frame of reference, that is roughly 6 times faster than the water flows out of a typical garden hose. To get that high velocity takes a high pressure blower. Relying on the draw of the stack will give a very week flow of air, and hardly any volume if restricted through nozzles.

[220 maple]

I'm jumping in here but first I'm going to tell you why my evaporator is a 3 by 16. Wood fired. We started making syrup in 1998 just for a hobby like most on this site. We used kettles that Spring, One day we had 250 gallons to boil and it took us over 24 hours to get it down to the point where we could take it into the house and finish it on the kitchen stove. Needless to say something had to be done. I decided I needed to educate myself, I didn't have a computer and I'm pretty sure this messageboard was not operational then, I visited other syrupmakers, a Mr. Garnett Whetzel offered for free his old 6 by 16 english tin evaporator. the only thing wrong with it he fell a sleep one night boiling and burnt oneside. My father picked it up and cut out the burnt side, cut the arch also and brought it back together. We have a 3 by 16 three pan vermont evaporator, it worked pretty good until our cousin in Baltimore who has a high tec machine shop offered to make us all new stainless pans for it for no charge. They work real well also, the only problem. The last foot to foot and a half in the back of the flue pan will not boil very good. We have a blower that makes the rest of it boil like mad. We have tried everything to make it boil in the back end with no luck. I have toyed with the idea of putting a bubbler in the back section of the flue pan to gain some evaporaton. My personal experience, my 3 by 16 evaporator works, but it probably would work better if it was shorter!!!

[RileySugarbush]

220,

You say it would be better if it was shorter, but that would only be the the case if the sap in that last foot or so didn't even warm up. In reality, it is contributing. The fact that it is not boiling hard just indicates that the last useful heat has been pulled from your fire and your stack temps are down. Your rig is running more efficiently than most mine. Shorten the pans and you would evaporate a little less water for the same amount of wood. Increase your fire rate and you will evaporate a little more for a lot more wood.

[brookledge]

I'm jumping in here but first I'm going to tell you why my evaporator is a 3 by 16. Wood fired. We started making syrup in 1998 just for a hobby like most on this site. We used kettles that Spring, One day we had 250 gallons to boil and it took us over 24 hours to get it down to the point where we could take it into the house and finish it on the kitchen stove. Needless to say something had to be done. I decided I needed to educate myself, I didn't have a computer and I'm pretty sure this messageboard was not operational then, I visited other syrupmakers, a Mr. Garnett Whetzel offered for free his old 6 by 16 english tin evaporator. the only thing wrong with it he fell a sleep one night boiling and burnt oneside. My father picked it up and cut out the burnt side, cut the arch also and brought it back together. We have a 3 by 16 three pan vermont evaporator, it worked pretty good until our cousin in Baltimore who has a high tec machine shop offered to make us all new stainless pans for it for no charge. They work real well also, the only problem. The last foot to foot and a half in the back of the flue pan will not boil very good. We have a blower that makes the rest of it boil like mad. We have tried everything to make it boil in the back end with no luck. I have toyed with the idea of putting a bubbler in the back section of the flue pan to gain some evaporaton. My personal experience, my 3 by 16 evaporator works, but it probably would work better if it was shorter!!!

As I said before the length gets to a point where it cost more to make than you gain. So if you figure out the amount of money it cost to make an arch and flue pan an extra 2-3 feet longer and then it doesn't boil because to much of the heat has been used up, it doesn't pay
Keith

[motowbrowne]

Okay, I've got my dad going over to take a look at the 2x10 tomorrow. He is asking 4700 for it, but he said he could come down a little bit. I saw that his friend sold the same evaporator on Maple trader with hoods for 4200, but not necessarily in the same condition. New this evaporator would cost around 7800-8200, so being 12-13 years old, do you think that this is a fair price? Obviously I would like to get a good deal on it, but I want it to be fair also. As far as I know the pans are welded together, but have some (presumably lead-free) solder in the interior construction. the pans are stainless, as is the stack, but the sides of the arch are not stainless. This evaporator does not include hoods. Please let me know if you think this sounds fair.

thanks,
Ryan