I could really use some advice. I have an outdoor wood furnace supplying 180 degree water to my house. I have hydronic radiant floor heat on the first floor, it works great. We could not put radiant on the second floor so we have a heat pump there. Now I would like to run a hot water line from my wood furnace to the second floor and put a water-to-air exchanger in the air handler. Should I install a second thermostat to just turn on the fan or should I try to wire everything to a single fancy t-stat? My heat pump has normal heat and emergency heat so adding the hot water heat would make 3 stages, right? Naturally I want to use the hot water as the primary heat source, say set that to 72, then have the heat pump kick on at 65 in emergencies or when I can't feed the fire. Anybody done this? Any advice? Thanks.