Stack Height

[VTnewguy]

Hi everyone, we are setting up our 2x6 leader evaporator for use this year. I was just wondering how high most people go for their own stack? I know the general rule of thumb is double the evaporator length, but for us that barely gets out of the sugar house. Any thoughts would be greatly appreciated.

[psparr]

More height won't hurt to a point. Could potentially create too much draft. May need to restrict the back pan some. Only way to know for sure is to run it.

[wiam]

I had close to 20' on my 2x6 to clear the roof. No problems with that.

[VTnewguy]

So when you say too much draft, would you have put some bricks in the back half of the arch to restrict the air flow?

[maple flats]

When I had a 2x6 I had 17' of stack. You will not be too high. The 2x evaporator length is just the minimum, the max might be well over 3x.
If you brick the arch properly you should have no issues. Thus if raised flue, have the space under the flues small, mine is less than 1", if drop flue, do the same, less than 1" open under the flues. Do not restrict the air flow using a stack damper.
On my 3x8 the stack is 19' tall, I have about 3/4" space under the flues once I get back to the end of the ramp. I then have high pressure air blowing in both under fire and over fire, and I do not shut the HP blower off to fuel, I get no smoke out the fill door when I open it and my boil is a hard boil all the way to the back of the flues pan, but my stack temp is usually in the 700-850 range. If my draw was too hard, the stack temp would be higher because the draft would pull the heat back and out before it had been put into the boil.

[VTnewguy]

Thank you so much for the info! It looks like we are going to be about 18' . So we should be in the right ballpark.