Quote:
Originally Posted by JDT
I never have figured out how they work in conjunction with each other. I know the heat pumps will only work to a certain temperature but it seems to jump back and forth between the two even in temperatures that should allow the heat pump to work.
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Jim,
This is how I understand my setup with a single stage heat pump and two stage furnace when using Electric Heat setting.
There are three stages: Stage 1 - Heat pump; Stage 2 - Heat pump and low gas heat; Stage 3 - Heat pump, high gas heat.
If thermostat is set to 70°,
At 69° (1° below set) - Stage one activates - heat pump.
At 65° (5° below set)- Stage two activates - heat pump and low gas heat.
At 63° (7° below set)- Stage two activates - heat pump and high gas heat.
Stage 1 will be the primary heat source as long as the heat pump can satisfy the thermostat, 71°. If the temperature drops to 65° or the heat pump runs continuously for 20 minutes, the heat pump cannot satisfy the thermostat so Stage 2 activates. If the heat pump cannot satisfy the thermostat for three consecutive cycles, the heat pump is locked out for two hours and Stage 2 low gas heat only will become the primary heat source. After the 2 hour period, Stage 1 will activate at the next new request for heat by the thermostat. After the initial lockout, anytime Stage 2 is activated, the heat pump will be locked out for another two hours. Only after Stage 1 alone satisfies the thermostat or the thermostat is turned off is the 3 strike counter reset.
Stage 3 will activate at 63° or when Stage 2 has run for 20 minutes.
There is no lockout in Stage 2 or Stage 3. They will run until the thermostat is satisfied.
The Gas Heat thermostat setting is similar to the Electric Heat setting. Stage 1 is low gas heat and Stage 2 is high gas heat. The Gas Heat setting follow the same algorithm as above except there is no Stage 3.
Hope that helps.