copper stack preheater

[MaplePancakeMan]

Hey guys, i want to put a preheater copper coil around my stack i was wondering how big of a pipe should i use its a 2x6 and it has a 12" stack also how many coils should i wrap around it. I know that i should have a vent and is that as simple as adding a t fitting in the coil wrap with an extended pipe up from the t to vent? and how many of those should i have.

Any pictures would be great.

Steve

[nymapleguy607]

I would be cautous about going around the stack. I think you would have problems with it wanting to scorch, not to mention water dripping. Could you just build a hood and preheater for the flue pan. On my evaporator I get 200 degree sap out of the preheater, and alot of condensate to clean with. If you dead set on going around the stack I think I'd go at least
1/2" copper.

[MaplePancakeMan]

well, its around a double wall pipe so its set off the main stack so that should make it a bit better maybe?

[MaplePancakeMan]

I suppose i could just attach it above my flue ban and achieve the same results. but a hood isn't in my budget this year. Do i have to have any sort of pitch toward the float box?

[warners point]

I have a 2x6 with copper tubing wrapped around the stack. Personally I think it is a waste since I'm only gaining 10 degrees in sap temp. My coil is .5 inch diameter and since I'm running 40 gph on the evaporator the valve on the coil is pretty much wide open. If I was doing 20 gph I would probably get a higher sap temp. I hope to build a preheater and a hood this winter if I can find the time.

[palmer4th]

I put foil around mine the a couple years ago and it helped heat it up a ton!!

[nymapleguy607]

I suppose i could just attach it above my flue ban and achieve the same results. but a hood isn't in my budget this year. Do i have to have any sort of pitch toward the float box?
My preheater comes in at the back corner of my flue pan. The preheater rises about 3-1/2" over about 36" towards the front of the evaporator. Then the sap drops back down to the same level it comes in at, then connects to the float box. I have a drip tray under the preheater to catch the condensate water that connects to the drip edge inside my hood.

[syrupdreamer]

MaplePancakeMan,
I once used this exact system on my evaporator. I had a vent and even wrapped it with fire blanket to try to help rise the temp. I had very little temp rise and was really a failure. I went to a preheater over the flue pan a acheived much better results. Good luck.

[Bucket Head]

I experimented also with a copper coil heater. Like the others, I would have been better going with a traditional preheater, which I have now. It did not work very well- you just don't get enough heat transfer. And this was around bare smokestack. If you have multiple wall pipe, you will see even less temperature rise because you have less heat there at that outside surface. A hood and preheater, despite the higher price tag, is the way to go. The performance gain is well worth it.

Steve

[maple flats]

While many have tried and almost all have failed, favoring a hood and preheater method, fellow trader Johnny Cuervo used a stack heater successfully. Check out his photo albumn to see how he did it. His was on single wall stack. Double wall stack would not have enough heat to do it without a huge amount of copper to transfer heat, far more cost than a hood method I would think.