Hunter wood/Norton electric combination furnace

[rayhylanf]

Hello, I have an early to mid 80's Hunter Wood/Electric Forced Air furnace. Recently purchased home. Electric side works without issue with its own thermostat.

Thermostat for wood side can tell it makes contact(mercury switch) , will start fan once wood box is up to temp. First couple of starts would cycle off short 2-3 min run , but then would kick back on and run forever - not turn off when expected/when house temp was achieved or if I turned off thermostat completely. I watched the limit switch turn during this sequence , seemed to be working the way intended but turning backwards to shut it off quickly ( after reading about them, making sense if cold air still going over the bi-metal winding inside the plenum ) suspected the bi-metal was worn out (likely original 40 year piece)

I replaced Fan Limit switch as I expected my issue was with it. New Fan Limit Switch is behaving the same. Starts and shuts off, after 2-3 minute run, even with the thermostat turned off. I have adjusted fan limit switch to 90 - 130, and the high is 200. I am missing something to make this right, having hard time finding any local help or manual online. Anyone have one of these units? I can post pictures soon -

 

[brenndatomu]

Sounds like it is working normally...a wood furnace doesn't shut the duct blower off when tstat temp is met, it can't, the fire would melt the furnace down...usually the tstat just controls a damper, or a small blower feeding forced air to the fire, so when the set temp is met, the damper closes, or the small combustion blower shuts off, which starves the fire for air and makes less heat (also makes creosote in your chimney too) but there is no stopping the fire until it burns out, so part of learning to heat your home with a wood furnace is learning to load the furnace with just enough wood to keep the house temp tolerable until the next loading...this time of year that may be once every day or two, when colder itsy be 2-3 x/day.
Make sure you are feeding it dry wood too (wood that measures less than 20% moisture content internally...which is tested with a wood MC meter, probing the middle of the wood on a freshly exposed face, preferably on room temp wood, and tester pins parallel with the wood grain) testing the outside of a round or split, or the end grain will tell you nothing of value.