My geothermal unit was installed this fall, so I am just now experiencing cold enough weather to use the system. My unit operates-runs-non stop for up to three hours without stopping even after it has reached temperature setting. Mostly it runs on the first stage. The thermostat says the heat setting matches the inside temp. The outside temp is 42 while I have the thermostat set at 68 inside. Is this normal? If not, could the termostat be defective? Set in the wrong place? Any first hand experiences with operation of the units would be appreciated.