Can you overfire a forced air wood furnace?

[CowboyAndy]

Title is pretty much self explanitory... I figure no because of the blowers moving air over the heat exchanger.

On my newmac cl86 there is an air control fight on the door, to be used when the power is out. Sometimes in the morning I open it to get the fire going nice and hot, usually only for 20 min or so. Is this a bad thing?

 

[johnsopi]

I have a Yukon Big Jack wood furnace. I think you over fire it. With the ash door open and the combustion fan on
I can take the smoke pipe temp up to 600 quickly. One other thing which is hotter the stove top temp or the stack temp?
With my furnace there is really no way I could get a stove top temp.
I love having a wood furnace all rooms 75 deg. only wish I had a glass door to see the fire.

 

[Duetech]

I have had two differeent types of wood add on furnaces and both of those warped from hot fires.

 

[smokinj]

Title is pretty much self explanitory... I figure no because of the blowers moving air over the heat exchanger.

On my newmac cl86 there is an air control fight on the door, to be used when the power is out. Sometimes in the morning I open it to get the fire going nice and hot, usually only for 20 min or so. Is this a bad thing?

you can over fire them if you leave the ash door open to long

 

[pybyr]

yes. don't ask me how I know, although the wonderfully overbuilt old wood-air furnace that I used to use, built like a locomotive, with cast-iron liner reinforcements in the firebox, was none the worse for wear-- when you smell a strong odor of old dust roasting in your ductwork, you know that you overshot the sweet spot of how much fire to build, and how much air to feed it... furnaces with less big iron in their crucial components (which is most of what is on the market today) may likely _not_ survive such irrational exuberance in the long haul...

 

[laynes69]

Thats what those clearances on the ductwork are for. Imagine 300, 400, 500 degree heat going through the ductwork. I have seen them with the pain blistered off the jackets, the grates warped so bad they won't move. I've came close once when the power went out, but as long as you damper down, and follow the duct clearances you are okay. Its scary though when they get out of hand. Not something you can kill instantly.

 

[pybyr]

Thats what those clearances on the ductwork are for. Imagine 300, 400, 500 degree heat going through the ductwork. I have seen them with the pain blistered off the jackets, the grates warped so bad they won't move. I've came close once when the power went out, but as long as you damper down, and follow the duct clearances you are okay. Its scary though when they get out of hand. Not something you can kill instantly.

that's why I have always been careful about clearances above all else- and when in doubt, put a big surface of reflective metal panel, mounted on spacers, between anything hot and anything combustible

 

[CowboyAndy]

So if this isnt ironic, I dont know what is...


I go home yesterday and go to the basement to load up. When I walked into the house, i noticed a smell. The same smell we got for the first 2 months of operating a new furnace. I go and check, and I can say with 99% certainty we over fired it. The spec sticker on the front was melting (ont of those foil type stickers). Not sure what happened, but the top of the front of the furnace was REALLY hot, as was the plenum, and the blowers were running but not constantly... The hi/low is set to something like 150 high, and the limit is 200 it was at 185. i just barely touched it and it came on. Bad switch??

 

[laynes69]

If its a limit/control, then it could be sticking. My old one did it, except for it wouldn't shut off. I would go downstairs, touch the furnace and off it went. I purchased a new one, that one didn't work properly. Got a replacement and its fine now. I would probably replace it if its doing that. Not sure if they can be cleaned.