How big of a fire?

[Maplewalnut]

For wood burners....Do most of you push your fire up the slope of the arch a little or try and leave it over the grate? I got great evaporation rates pushing it up a little but also had the bottom few inches of my stack glowing red every now and then. Just curious.

[Breezy Lane Sugarworks]

I tried to keep it pretty much over my grates. and a few inches from the doors, to allow for more combustion.

[brookledge]

I never tried to push wood up the slope. The only thing to be careful is if you have drop flues. You don't want to be banging them with wood. But as far as whether it will do any harm, I don't think so.
Keith

[Fred Henderson]

I think that it was Parker that said not to have the wood over 2 layers thick and over the grates.

[ibby458]

Last year, I had a 2x9 with 3 pans. I got my best evaporation rates by pushing as much wood under the middle pan as I could. With the forced draft, I often had stack temperatures in the 800-900 range, but that was the only way I could get 50 gph.

[Hal]

Before I rebuilt my arch I always used to push wood up the slope. It definitely boiled faster this way. The worst problem was that without forced draft, it would build up a bed of coals big enough to roast an ox, which would still be there after all the sap was gone and I wanted to go home. As rebuilt, my firebox is longer, and flat bottomed, with a vertical wall at the back. With sealed doors and plenty of forced draft, there is very little build-up of coals, and I can put the wood anywhere I want to.

[parsissn]

My main hobby is steam engines so we spends lots of time around fires and making them work to our best advantage. The firebox in an evaporator is functionally very similar to a steam engine. The key is to make sure you don't have cold(er) air that is able to leak around the fire. You want to make the air either go directly through the fire or at least up and over the fire. This means you should try to lay your wood up so that there is no big air gap between the front of the fire and the slope of your arch. You also want to make sure to have the wood covering side to side. The ensures your air must make contact with the fire before moving on through the evaporator. When you lay in your wood you might try to criss cross it some, especially if you fire with slab wood. This helps keep the wood stack open so air can move through it and you get good combustion. Just my input from experience with contained fires.

Mark

[maplehound]

Mark,
That explains alot to me. On my Dellair evaporator I have factory installed forced air. The air comes through the duct work and into a smaller box in the ash pit. the box efectavly makes the ash pit smaller and just lets the air go up into the center of the fire and not around it. I was never sure why they did that instead of just blowing air into the exsisting ash pit. What you said does explain why they do it this way and I must say it does work great.