I notice at certain times that the heat pump and electric furnace are running at the same time. This happens if it is cold and I increase the thermostat setting a few degrees higher. I also noticed this happening if it is very cold and the heat pump is running for a longer than normal time. Is this normal? I am using a White Rodgers manual thermostat. The Coleman heat pump is a 3.5 ton unit. The heat pump has an outdoor thermostat set at 25 Degrees F.

Thanks,
Steve

If the indoor temperature cannot be maintained by the heat pump only the thermostat tells the electric heaters in the furnace to turn on. Some heating systems also turn on the electric heaters whenever the heat pump outside unit goes into defrost to temper the air in the home or maintain the temperature set point.