operating question

[rsting]

Hi, I've got a stupid basic question on my momma bear. Burning year old oak, fire burning well, how far open from closed position would you consider normal on the air controls? I haven't used an air tight stove before, and I'm still trying to get used to it. Also, I have a damper in the pipe, and leave it just tilted, not closed. Is that correct?
Thanks!

 

[coaly]

Good drafting chimney, a half turn open to a turn and a half is normal. Depends on heat output required and heat required for chimney. Mama Bear heating 1500 SF at 30* outdoor temp should be an average heat requirement of about one turn open. As it gets colder outside draft will increase allowing more air into stove at the same setting. So it doesn't have to be adjusted for a lot more air as it gets colder until down around zero when you would probably run 1 1/2 turns or more for maximum output. I don't think I ever needed more than 2 turns each - but I have a 6 inch insulated chimney that requires very little heat. A huge oversize chimney could take all the heat the stove has and not have enough to heat the area. So the chimney has a lot to do with the air adjustment.

When starting with paper, cardboard and kindling, open intakes a few turns. If the kindling roars up the stack, close damper slowly to stop roar. This slows the chimney. (the flue damper is a chimney control to decrease excess draft) This keeps more heat in the stove to get the larger pieces started than leaving it roar up the stack. You should be able to close both intakes down to 2 turns to a turn and a half open as it comes up to temp. Open damper when not needed to slow the kindling. When fire is established, about 1 turn should be normal. This depends on chimney size (flue diameter) indoor or outdoor and material, (masonry requires much more heat, insulated steel less) you may need it farther open or closed to allow enough heat up for proper operation. You should have a thermometer on the pipe before it dumps into chimney and set controls for keeping flue 250* or above all the way up. This is guess since inner flue gas temp can be 50% or more higher than surface temp. Creosote build up will show if you are running too cool, so check frequently until you know how much you are creating.
Heat output required is controlled by closing or opening intakes more or less. This is where sizing the stove correctly for the area and sizing for chimney is very important. Damper operation varies with chimney, weather conditions and fuel. The flue damper slows draft when necessary which affects the stove by slowing the air coming in.

 

[rsting]

Just wanted to say thanks. I followed your instructions today, and it made a huge difference. The stove went from good to awesome! Thank you so much!

 

[acp104]

Coaly,
Do you believe your very helpful tips on operation (especially for the intakes) would apply to most of the Fisher copies as well? I just installed an All Nighter similar in size to the Mama Bear, and am trying to get up to speed on how to operate it.

 

[coaly]

Yes. The adjustment of air and flue damper varies with fuel, connector pipe resistance and different chimney size and types. The only way to judge a stove is connecting it to the exact same chimney and pipe configuration and you would then notice any slight difference needed for operation and difference in heat output. Results are going to be very similar. What makes the difference in stoves is being higher or lower for ease of loading, how easy or difficult latching doors, or how hot controls get..... When you're used to a large cook top like a Papa Bear and go to something different, those are the things you notice. Same as an entirely radiant stove vs. convection type with double wall with air space to extract heat with blower through convection. You can't boil water on them, but they heat a larger air space. Operation is very similar with drastically different results.
The less heat required to keep chimney flue above 250* to the top, the more you can slow it down with damper or air intakes. Changing fuel will change your burning technique more than changing stoves.