2x12 Evaporator Idea?

[rob1640]

For this season I built a 2x4 evaporator with a 1x2 preheater pan out of a 200gal oil tank with a forced air system (old furnace vent blower). It worked great, but I will be tapping more trees next year, so I have already sold the
2x4.

I'm considering building a 2x12 evaporator for next year. My plan is to build a three pan evaporator. The back pan would be a 2x6 flat pan without dividers, the next pan would be a 2x4 divided flat pan, followed by a 2x2 syrup pan. The arch will be a homemade standard style wood fired system with two forced air blowers, one for over the fire and one for under the fire.

I know that this is an odd set-up but 2 foot pans seem to be very reasonably priced and very available, so I thought that this may make a good evaporator until my next bite by the maple bug (this year I had 150 taps, next year plan is 500-600).

Will this evaporator work well?

Rob

[WESTVIRGINIAMAPLER]

Rob,

Sounds pretty cool. I kinda always wanted a 2x12 flued evaporator with a 9' flue pan. It would be very efficient and I think I could get it up close to 100 gph. Oh well, not likely to happen but would be a very efficient unit.

[3rdgen.maple]

I thinking out loud here but 600 taps with flat pans on a 2x12 seems like you would never get any sleep when the sap is running. I used to have an odd ball size 30"x 7' arch, it had a 12"x30" finishing pan, and 4 flat pans behind that. I can tell you that the back pan was basically a preheater cause it would never boil just steam. There was alot of days when dad boiled all day and I boiled all night to keep up with 150 to 200 taps on that rig. So If you add an extra 5 feet to that I'm not sure how much boiling you would get in the back. I think you might be better off with the 4 foot pan in the back and use that to preheat the sap. I would Put a divider in that too so incoming sap would not cool the whole pan down. If you got a shorter rig with a flue pan you are gonna be happier and get a little more sleep.

[WESTVIRGINIAMAPLER]

You would have to have the proper amount of heat back there for it to work correctly. I run about 1400 to 1750 stack temps 4' past where the pans end on my 2x8, so I wouldn't have any problem with boiling back there.

[Haynes Forest Products]

Show me an inventer that doesnt have a pile of proto types. Go for it and report back ASAP. I would go for a longer fir box and longer wood but what do I know im an oil guy. I bet there used to be a one eyed Indian out there that had a buddy who asked him what the heck are you doing throwing hot rocks in that sap.

[WF MASON]

The idea was done in Canada years ago(15-20) by a company , they made short 20"long drop flue pans , the one nearest the stack had the deepest flues , like 7", then as the pans came forward the flues got shorter, then it had a couple syrup pans , all the pans were connected. They were soldered, and basic, I had seen a couple different ones, the interesting thing was the arch had a jib crane mounted by the stack with a arm that telecoped out to pick the pans off. It might of Belideau or one of the others up there who made them. I'm sure others have seen them.

[Teuchtar]

A few years ago, I extended my 2x6 by adding a 5 foot flue pan on an extended arch. With a raging fire, I could get the 5 footer to partly boil, but not nearly as vigourously as the 4 footer up front.
Sure, it was efficient. Stack temperature ran under 550degF, so the new pan was pulling energy out of the gas all right. But I was disappointed with slow boil.
The theory is that a flue pan should contribute 3 gal/hr to the boil rate, but with a long gas path, the fire temp is dropping and you don't get that ideal rate. I've lost the data I collected, but my recollection is I got about 1/2 the ideal rate gain. I suppose the pan has to be exposed to radiant flames to have such a high rate. For sure there never was flames under my back pan.
Maybe if I'd fitted airtight door and a blower I would have raised the rate back up. I tried the blower trick, but lost interest when I saw flames coming from my rafters.
I tore the system down last year when I put the RO in operation. The extra pan maybe gave me 25% production boost. But the RO can give you a 400% production boost. RO Rocks.

[hookhill]

We did pretty much what you are talking about. We had a 2.5x8 and added a 2.5x5 syrup pan to the back. Now the rig is 2.5x13. The pan that was added to the back gets the sap up to about 150 degrees. The sap is then pumped through the preheater that sits over the flue pan. This jumps up the sap to about 200. When the rig gets hopping it will do better than 60 gallons/hour. If we wanted the new pan to boil we would have to make the firebox longer and cut longer wood. This rig is for sale. We are buying a 4x12.

[brookledge]

Rob
Why wouldn't you want to use a flue pan and keep your arch shorter?
You will do better with a 2X8 with a flue pan than you will with a 2X12 with all flat pans like you are thinking.
Either way you are on the right track. Alot of efficiency can be gained by extending the arch. But there is a fine line on trying to get too much heat transfer. This would lead to slow boiling and the sap would flow slower through the pans causing darker syrup.
Keith