Smoke Stack Height

[dblact38]

How tall must a stack be on a wood burning evaporator? Any advice will help, Thanks all

[bowhunter]

The standard answer is twice the length of the pan, so a 2 x 6 would need 12 feet.

[jmayerl]

Any taller than that and it will have more draft, shorter will be less draft.

[Michael Greer]

Lots of old-time sugar houses had really tall stacks, probably because they were placed at the very bottom of the slope, which is great for gravity, and not so great for draft.

[Biz]

Is it possible to have a stack too high? I am putting my 18x48" CDL evaporator inside my new 8x12 sugarhouse. With the 12/12 pitch roof, it has a very high peak. I had 9' of pipe in the old sugarhouse which had excellent draw. I need to add 3' of pipe on the new sugarhouse which brings stack length to 12', now it will only protrude out the roof jack by about 1 foot. Should I add another length (brings it to 15' on a 4' evaporator)? Want to use stainless but it comes in 3' lengths and I would hate to have to cut it.

[n8hutch]

If you have an adjustable draft door on your firebox I think you would be OK, on the 2x4 I used to run we would adjust the damper depending on the barometric pressure of the day, sunny&dry/Damp&raining, we had A 16ft stack.

[BreezyHill]

It has been my experience that there is never to much draft. My current evap is a forced draft with 8" stack with 14' to get it out of the building. I piggy backed a second fan to force feed #1 fan and increased boil rate by 7-10 gallons per hour.

Visiting a customers sugar house and he had a 10" stack on the same size arch with natural draft and he was getting mid forties to my 37 max gallons per hour. I also run a very good preheater and feed the unit at 185 and his is cold from outside storage tank.

Since I need a new transition I will be changing to a 10". This will be custom fab at a SS shop.

[maple flats]

The stack should be the greater of the two, either twice the length of the evaporator, or 2' higher than the highest point within 10' on the roof. In your case it will be 2' higher than the peak, or 2' higher than the cupola peak if you have a cupola.