Smoke from the evaporator door

[Florio79]

I have a 2x4 evaporator... a lot of smoke spews from the door when I open it.... It is a home made evaporator shaped like a leader evaporator. It has a 6 inch stack about 7 feet long with and S bend. The ash door is not air tight... Neither is the main door.... There is a cap on the stack. What should I do to minimize smoke spew out of the door when it is opened? Longer stack or a stack with a larger diameter? Any guidance would be appreciated. I'm happy with how it boils.... Thanks!

[RollinsOrchards]

My first thought is larger diameter, but you could try getting rid of the cap first and see if that helps. Also if you can eliminate that S-bend in the pipe you will be farther ahead also.

I think some smoke will spew out the door no matter what. Perhaps you can bend a piece of tin and direct that smoke away from yourself and/or the syrup?

[maple flats]

7" minimum on the stack. You can just remove all but the first section for now where it attaches to the arch, and get a transition to 7 or even 8", then add enogh stack so you have 8' or more total.
What is the wood you are burning? How small is it split? How long has it been drying?
Anytime an evaporator smokes after the initial starting of the fire it is because the wood is not dry enough, not split small enough or you are not giving it enough air. When I had a half pint (2x3') and a 2x6 set and then a 3x8 set up until I added my high pressure air, the air inlet (draft door) was open at least half way and more often full open. It don't recall what the draft size was on the 2x3, but the 2x6 had a 6x12" door and it was usually propped up to a 45 degree or higher open, on the 3x8 the door is 8x14 and it was usually open over a 45 degree angle. You need more air, dry wood and a bigger stack. First try just adding 2' more of the stack size you have, it may help enough. You need a minimum of 2x the arch length so for you that is 1'. Then, no angles, no caps while burning.
On mine, in fact, I have a high pressure blower and that is turned on as soon as the fire starts and stays on until the fire is done for the day and the coals are most all gone.

[Big_Eddy]

Agree with maple flats. 7"or8" stack min and 10' would be good

You mention the ash door is not air tight. Do you run with it open? Or how much of an opening do you have for air? Do you have a grate and how much clear space (no ash or coals) is under it?

You need a large opening to allow air under the fire and a large enough stack for a good draw. Once the fire is going, my evaporator generates enough natural draft to suck leaves and small twigs off the ground up Into the ash space