Thermostat help

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Jan 19, 2021
I copied my post from a thermostat forum and wanted to be more specific about my heater beaters fire them.

Could use some help please.
I have a fire chief (which hasn't had any burn problems) indoor, that has its own duct blower which is controlled by a fan limit switch but the draft blower that gets the fire restarted has 2 wires r and w is controlled by thermostat.

I just installed a thermo pride oh6 oil forced hot air furnace also with its own blower and has 4 wire c, w, r, and g. I also fresh installed the rth9585wf to the oil burner.

I want to be able to hook both furnace up to a single thermostat with my wood furnace as my main with the oil burner and fan not called upon. How can I either be able to set a temp max low temp were the wood furnace is no longer being called upon and oil takes over. Or if either one could be picked by myself and be the only furnace that runs until I choose to switch.


Minister of Fire
Aug 21, 2013
NE Ohio
Each furnace needs to be on its own Tstat.
Just set the oil a couple degrees lower than the wood...when the wood runs out the oil takes over.
If you don't want to/can't run a second set of wires, just go wireless on one of them.


Feeling the Heat
Feb 6, 2020
Hicksville, Ohio
Or if either one could be picked by myself and be the only furnace that runs until I choose to switch.
Run the thermostat wire through a standard household 4way switch. The white wire connects direct to both furnaces. Then connect the red wire to both upper terminals on the 4 way. The bottom terminals will then each connect to a different furnace. The 4way switch will act as a transfer switch allowing you to select one of the two furnaces but not both.
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