Copper tubing preheater size?

[mike z]

I'm doing the old wrapping copper tubing around the stack (actually not around but coiled against stack base), for preheating sap. The question is: should I use 50' 1/2 in. or 25' 3/4 dia.? I'm concerned that I may not get the volume I need to keep up with evaporation (30 gal. hr.). My storage tank is sitting only 1.5 ft. above the evaporator. Thanks Guys

[Flat Lander Sugaring]

did that years ago, actually we did the wrap first then we drilled holes in stack and ran copper right through it several times it worked ok. Some heat to the sap before it gets into float is better than cold sap any day.
I would use 3/4 and wrap the hell out of it, as much as you can in that 1.5 ft

[adk1]

I thought that wrapping too much would scortch the sap? is this true? also, doesnt it cause a vapor lock?

[Flat Lander Sugaring]

I do remember having vapor lock issues. I'm talking 15 yrs ago we did the wrap thing and through the stack. Kinda hard to remember exactly.

[S Culver]

I wrapped 20' of 1/2 " around my 8" flue and I'm getting pretty good results. I go from 38 degrees to hot about 120 . I used a valve at the tank and one at the pan. when bring in sap I open the top to fill the line and crack open the valve at the tank. This way the sap stays in the line around the flue longer. When I am not having the sap run in ( shutting down or starting up) I close the top tank valve and open the bottom all the way and let it drain. If I do this again I think I would go for more than 20' though.

[mike z]

What is your evaporation rate? The 1/2" keeps up ok?

[S Culver]

I am on 2x6 flat pans with a blower. I would guess about 15 gal hr so I am using only a small stream in when boiling.

[S Culver]

At 30 gal hr you should be fine with 1/2" as I'm not running 1/4 capacity but I would run 30 or more feet wrapped. start with a few screws into the flue so you can get the grade right on the coil and not a lot of gullies which i suppose would cause problems.

Good luck
Sloan

[jfroe939]

I used a 25 foot 1/4" copper tubing and it worked well the first year. I cook on a 2.5' X 6' flat pan. It probably didn't keep up for flow volume, but I guess we didn't just want to throw the copper away. Not sure what size they make, but go larger than 1/4" but probably not bigger than 1/2". And certainly go as long as you can because longer = prolonged exposure to heat. We take down our stack annually. I kinda think the trick is to keep your copper in as tight of a loop as you can in storage. Don't put your stack up first and then put your copper tubing on as it will never get tight to the stack and you won't get good heat transfer if you try to wrap it on after the fact. Heat doesn't transfer through air. It needs direct contact with the stack. Vapor lock was an issue. We'd start out with the stack already hot and then try to attach our 1/4" plastic tubing to the top of the cooper and we'd keep it a tight fit using white plumbing tape so it just kinda slips on and off. Then it would hiss and sputter and after 15 seconds we'd get a flow of blackened sap. After the sap cleared, we'd swing the copper end over the edge of the pan and depending on how hot the stack was we could get the sap uncomfortable to the touch. If the copper wasn't tight to the stack, sap was barely luke-warm. That's my findings. Cheap and effective. Ideally I think I'd like 50 feet of 3/8". Don't go short to save 20 bucks because you'll regret it.