2 X 6 Raised Flue - Better Boil and Air Flow Question

[beltechc]

New to raised flue evaporator this year.(2 X 6 Small Brother) I was using a flat pan home made system prior to this. I think I should be getting a better gph then I am.

I notice that the flue pan boils rapidly in about the 1st third closest to the fire but not so much near the stack - is this normal or should I have a good rapid boil throughout?

Also what is normally done for air flow. I have the damper below the doors wide open but still leave the doors open some. Should I close the doors completely and just use the lower damper?

Also the damper in the stack seems to do a good job of controlling the heat to the syrup pan when closed and the flue pan when opened. Just wondering how you guys out there run your systems.

Basically new at this and any help would be great.

[mike first timer]

I run my 2x6 with draft door open and other two doors closed and no damper in the stack.Mine boils hardest closest to the syrup pan but the boil does work its way to the back.

[beltechc]

With your stack damper open and a hard boil in the flue pan do you still get a good boil up front in your syrup pan?

[para2]

I used to own a sb 2x6,no dampner in stack! You want the draft of your stack to pull the heat all the way thru. Keep draft door open. Fire every 6
to 7 min alternate doors and keep wood close to doors. Don't push wood back! Good luck.

[Middleton Maples]

My 2'-8' flue pan only boils rapidly in the first third and a light boil everywhere else. Don't worry, I think its normal, I am boiling more an hour than what they rate it for anyway.

[nymapleguy607]

With my evaporator I can usually get the first 2 ft of the flue pan to boil good and hard, sometimes it will go back 3ft but not often. You should run with the doors closed and open and close your draft door to control the heat output. If your syrup pan wont boil but the flue pan is boiling good it means you have too much draft, what I did was close the area under the stack collar a bit. I wouldnt use a damper in the stack. If you dont have one get a stack thermometer that has a probe in the stack natural draft should be run in the ball park of 800-950 degrees. You are likely to never have a full giser boil through the pan but there should be some bubbles coming from the back of the pan. Good luck

[Bucksaw]

With my evaporator I can usually get the first 2 ft of the flue pan to boil good and hard, sometimes it will go back 3ft but not often. You should run with the doors closed and open and close your draft door to control the heat output. If your syrup pan wont boil but the flue pan is boiling good it means you have too much draft, what I did was close the area under the stack collar a bit. I wouldnt use a damper in the stack. If you dont have one get a stack thermometer that has a probe in the stack natural draft should be run in the ball park of 800-950 degrees. You are likely to never have a full giser boil through the pan but there should be some bubbles coming from the back of the pan. Good luck

I only have a 2x3 evaporator but was wondering why you wouldn't use a damper? I added one to my stack because it seemed like I was losing a lot of heat without it.

[nymapleguy607]

Generally with a larger arch you need all the draft you can get so the flames are pulled back between the flues. With a 2x3 your firebox is probably the same size as your pan so the coals will do alot to help boil it. In that situiation I would say keep the damper

[Bucksaw]

Thanks for the clarification. I have been experimenting a little just to see what works best and the damper seemed to help keep the stack temp down a little and keep more heat in the arch. After reading about the half pint and how they recommend making a firewall in the firebox I tried that too but need to move it back a little as I think it decreased my gph a little. Sorry didn't mean to hijack this thread!