...furnace? I want the heat pump thermostat to be set on say 65 and the wood furnace to be set on say 70 the wood furnace thermostat only needs to be able to control fan.
Wire to R & G on indoor air handler terminals.
You could have a problem with feed back through the other thermostat bringing on the compressor depending on the thermostat you have for the heatpump.
You may need an isolation relay.
