Combustion air issues

Hi guys, I'm new here ,and new to wood burning as well, we have moved into a house with a Kinetic solar burner (sounds like it should be powered by the sun and not wood LOL), anyway the questions I have are about the combustion air fan operation. First of all thank you in advance for all your help, suggestions and criticism. Sequence of events go like this, I start a good fire, close feed door, close bypass damper and set stat to call for heat. Combustion air fan kicks on, plenum temp rises to 115-120 and the circulation fans turn on, I in turn put the gas furnace switch to on. At this point all is good warm and toasty. When the stat temp is satisfied, wood furnace blowers shut down and the gas furnace blower runs until that plenum cools down as well. Here comes the issue, when everything is off (not calling for heat because room temp has been satisfied) after an hour or so of shut down and temp comfort the stat is still NOT calling for heat (that is good), however the combustion air fan kicks on and won't shut off until I kill all power or the logs burn out. That definitely eats wood for no reason. Shouldn't the fire just be down to smolder until the stat cools enough to call for heat? And why would the CA fan kick on in the middle of? That will make it not very efficient. Below is a pic of the front of the unit. Thanks again for your time.

TCaldwell said:

Is there a temp sensor or timer that Controlls the ca fan, do you have a operators manual for the furnace? Is there a controller or stack temp switch, need more info

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I thought the temp sensor would be the tstat so when it reached desired temp it would shut off. Perhaps I am mistaken (would not be the first time I assure you). I have nothing on this furnace and I can't find anything on the net. No stack temp switch either. When the furnace is cracking the chimney pipe runs around 300 and the plenum temp is around 140-160. If I turn the tstat down well below room temp the supply blowers and CA fan shut off, but the NG furnace will run for a long time before it cools down and goes idle. And after that I could wait half an hour or so then I heard the CA fan kick on and the tstat was still set well below (15 degrees) room temp. This thing will plow through wood with that CA fan running. Yesterday I shut the entire electrical system off at 10:30 AM, fed the furnace small (3-5 pieces) loads and never had to hit the power till about 7:30 PM (wife said she was chilly) and the digital tstat for the NG furnace read 71 but the humidity in the house dropped to 51%. I left the blowers running for 1 hour and everything (temp and Humidity) was at a comfortable level and the plenum temp remain all day long between 120 and 160. Hope I'm not confusing the issue. Maybe that is the way I should run the system? Don't know about colder days yet. We do live in northern Illinois.
Thanks for your help
Dennis

TCaldwell said:

Not sure why the ca blower would energize when t stat satisfied, need to trace wires from ca blower and see where they land to find what Controlls it to get a better understanding

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Thanks, I will try to take the back apart and investigate the wire before I fire it up tonight. Room temp was still at 70 this AM I left just a small fire burning when I went to bed so it would be cool today when I look at it. Could the fan control limit switch have anything to do with it?