Air under Fire

[Eberzin]

I have a old Vermont Evaporator arch for my 2x4 drop flu pan. It has a firebox with grooved grates where air comes up thru from the draft. Can I put a blower at the front of the unit blowing horizontal thru that draft door. If I do, will I need to do anything else, like a stack damper, or a diverter under the grates to push the air vertically? If I cannot I suppose I could cut a rectangular hole in the back and force it forward. Just trying to see if I could go thru the front and get good results, and save some time. Any advice greatly appreciated. Thanks

[maple flats]

You can blow it in thru the front or the back but a sealed entry is best, so the air must go in and not simply escape and go thru the blower again. Also, it helps if you block the front 4-6" in at the door so the air is pushed thru the wood and doesn't just go up and around since the front of the grates as a rule get less ash and coals on them.

[Eberzin]

Thanks, I put the blower in the draft and put blanket on the sides and a big piece that covered the bottom half of the door and the gap in the top of the draft. After reading your reply I think I can tighten up some more under the blower. It really made a difference when I did this. Did you mean to cover the first six inches of grate openings right behind the door? If I do that would it lower the boil rate in my syrup pans? Thanks again

[maple flats]

If you do that the boil will be harder in the pan. Without it some of the air blown in will take a short cut and bypass the wood, that air will then cool the front portion of the pan. When the air is forced thru the wood, the fire gets much hotter and that gives you a faster boil.