Can't retain the heat

[notacarpenter]

For the past five years, my evaporator was nothing more than a 2 X 4 pan on a cinder block fire pit. I had a simple smoke-stack coming out from the end to redirect most of the smoke. Although basic, this set up produced a lot of heat, giving my pan a constant rapid-boil. This year I received a free old wood burning stove which was modified by cutting out the top for my pan to fit right over it. I thought things would be simpler and more productive, but it does not produce enough heat for a decent boil. The fire is pretty intense but I notice that the flames pass under the pan(practically untouched) but goes straight out through the smoke stack (too much draft??). I don't have a damper but I was thinking of putting a small obstruction at the bottom of the stack opening (8 inches). All I know it's talking me almost twice as long to boil. Any suggestions?


Greg

[PerryW]

Is there a way to put some kind of ramp (made of bricks or stones) that forces the flames to go up against the underside of the pan? My raised flue 3x10 had a ramp that goes up within 2" of the bottom of the pan so the flame is forced to hit the bottom of the pan.

[beaglebriar]

I put a firewall in my 2x3 that basically blocks off the stack hole. It's about 2" from the bottom of the pan. Working good so far.

[optionguru]

I'm certainly no expert but an 8" stack seems big for a 2x4 pan. My old pan was equivalent to a 2x4 and it used a 6" stack my new evaporator is 40" x 48" and uses an 8". I also agree with the others, there should only be a few inches between the bottom and the pan towards the back 2' or so.

[Cabin]

Is there any way to put a damper in the stove pipe???

[brikel]

Greg,

I had an old wood burner that we took out of our house and tried something probably similar to what you are doing. I had the same results, great heat but not efficient. I ended building an arch out of that wood burner by cutting the back out of it and extending it to accommodate a new pan. It is working great for me this year. Good luck hope things work out for you.

[notacarpenter]

Is it a simple wall, or is it built like a ramp toward the stack hole? How much of the hole is blocked?

Thanks.

[beaglebriar]

You can build a wall out of brick about 8-12 inches in front of your stack. Build it up to about 2" below the rail/pan. Here's a picture of mine. I added two or three more courses of brick after this picture was taken.11207

[PerryW]

Is it a simple wall, or is it built like a ramp toward the stack hole? How much of the hole is blocked?

Thanks.

They use a ramp for longer evaporators. For shorter evaporators, a wall would probably be better as there is really not enough room between the firebox and the stack.

[eustis22]

Thank you, Beagle and perry....the past few years I had a sand ramp on my 2X3 and just couldn't get or maintain that perfect boil. This past summer I put a wall of brick the same way you've posted (although I seem to have used a lot less than the required refractory cement :) ) and I am anxious to see what this portends for this weekends boil. I'm a little less anxious now.