I've successfully installed my new Nest Learning Thermostat (Gen 2, I think) to operate my heat pump with electric heat as my emergency heat source. However, I have a wood boiler system also (circulated hot water from wood stove with its own heat exchanger in my duct-work) that I use when outside temperatures go below 40F. I've watched a YouTube video of how to set up a Gas furnace as an alternate heat source to a heat pump, and I'm guessing I can do this likewise for my wood boiler. I'm guessing that I'll do everything that this video showed (manually move W2 wire to W1, etc) except that I'll choose "Geothermal" as my alternate heat source as well as select the Fan to operate [Note: the Gas system has its own system for operating the fan, so its Fan selection is "Don't operate"]. Question: Is Geothermal the correct selection for my Wood boiler system? I wish the selection choice included "Other" or "Wood Boiler". All I really want Nest to do is turn the fan on when the temperature setting calls for heat since my wood boiler's heat exchanger is already supplying heat.