We just moved in to a 2007 built house in northern Minnesota. It is single story 3200 SF timber frame home with a 4 ft crawl space beneath; where the majority of the utilities are located. The home has an open loop geothermal system with both an in-floor radiant distribution as well as a forced air distribution system. The forced air portion has a propane furnace backup and it also serves as the air conditioner. The geothermal system has two FHP heat exchangers. I am totally new to geothermal so I don’t know exactly how the system works. It appears there is a single thermostat that controls the forced air distribution and six other thermostats that apparently control zones for the in-floor distribution system. The prior owners told us they rarely if ever turned on the in-floor system except one remote bedroom zone. The domestic water heater is off peak electric however there are two 1/2” copper lines entering it near the bottom and I believe they are coming from the geothermal heat exchanger. There is another water heater in the heated garage and I believe this one is just a storage tank for the in-floor system. We have been in the house only 2 weeks now and since I know very little, I turned off all in-floor zones and relied totally on the forced air distribution. The weather was quite nasty, getting to -20 F several days but the house stayed nice and warm at the set 71F temp. I am now going to try turning off the forced air portion and rely only on the in-floor distribution to see what happens for the next few days. My question are pretty basic, so please bear with me: Is this called a “dual stage, dual fuel GSHP system? Obviously, I want to avoid use of the propane as the fuel source as much as possible. What is the most efficient distribution system, the forced air or in-floor? How should I set the thermostats to operate? Both systems at the same set point or one a few degrees lower than the other? Anyone have experience with the Nest thermostat? Would that be of any value on this system? If so, which one the forced air or one of the in-floor zones? Thanks in advance.