Flue pan not boiling as much in the back

[KReinisch]

Hello,

I have a 30 by 8 evaporator and I was just running a test boil and I noticed that the back 1/3 of the raised flue pan was not boiling as hard as the front. I have the arch ramped up but I'm not sure what else I could do. Do I really need to build the arch up in the back after ramp. I have about 2 inches of space there.

Thank You,
Kevin

[nymapleguy607]

On a raised flue evaporator you want the area under the flue pan as close to the bottom of the flues as possible. I have about 1/2 an inch of space between the bottom of the flues and the area behind the ramp. Last year I added a row of fire brick that were right even with the flues, about 12" from the stack collar, that really helped with the boil in the rear of the pan.

[mellondome]

Fire and heat will take the path of least resistance. .. which is not through the flues . Ramp should leave first 1/3 open to flame. Rest of pan bottom should be as close to the flues as you can get . The opening in the back should be no more than 4-6" for the gases to drop out of the flues.

[maple flats]

My raised flues have about 1/4" space under the flues. You must force the heat thru the flues for the best boil. Even with that said, you will get a more violent boil in the first 1/3 but it should still be a good rolling boil at the back end.

[morningstarfarm]

Might want to give a blower some thought..,a little air under the fire made a huge difference for me...

[Bucket Head]

I did what Jeff describes on my old 2.5x6 and it made quite a difference. I kept moving my row of bricks back until I got a little smoke coming out at me when I fired. Once that happened, I moved them back to the previous "no smoke" position. It took several boils to "fine tune" it. You would be (and will be) surprised at how little of an opening is actually required for exhaust. I never measured it but it was around 4 inches. Making a lot of heat, and then keeping it in the flues can be tricky, but it can be done. Good luck.

Steve

[David in MI]

How tall is your stack?