Hi guys,
Need some advice/direction and hopefully some diagrams to follow. I have recently installed a coal boiler and installed a coil in my existing duct work. I am going to use my existing propane furnace fan to blow the heat off of the coil.

What I am unsure of is how to add an auxillary thermostat so the fan will kick on from my furnace, but not the heating component of the furnace?

I'm using the coal as the primary heating source, but only want to use the fan on my furnace to take the heat off the coil. Please help. Thanks Bob (rjbeery@<hidden>)

Does your thermostat have a fan on switch? cheapest way turn it from auto to on other wise you will need a fan limit wired to coal stove

I would suggest using a dual-fuel/heat pump thermostat if you want the system to be fully automatic. The coal boiler and furnace fan could be controlled as the first stage, and the LP furnace will kick in if the coal fire dies and the indoor temperature starts falling.

I recommend going with KC13's advice and you will be happy and pleased with how automatic it will work. A dual fuel tstat will give you many capabilities beyond what you want to do now.