gas electric furnace

Heat pumps are only good down to about 40 degrees. At that point they cannot keep up with the heat demand and will switch to gas.

1. A heat pump only works dow to 40-42* f. When there is no external heat to exchange, it cannot exchange cold for heat.
2. If the temp is 3-5* f, depending on the heat pump, below the thermostsat setting, the gas furnace will start, take over.
3. Below 40-42* I would turn off the elec heat. It just causes the heat pump to work hard and produce nothing. Creates wear with no purpose/gain.

You probably have a heat pump. On our unit if temperature is below say 40 degrees it automatically switches to furnace.

That's the way it's supposed to work. If it's still warm enough for the heat pump to work, and the thermostat is set more than 4 degrees above the actual inside temperature the gas furnace will assist until the temperature is within 2 degrees of the temperature called for by the thermostat.

The minimum temperature for the heat pump to work varies between coaches. On our 2001 with the same basement air system you have it would work down to about 36*F. I know of other people with the same system that could get it to work down to as low as 34*F and others that couldn't get it to work below 40*F. The overhead heat pumps on our 2013 Adventurer won't work below 40*F.

When the thermostat is set to use electric heat will try to use the heat pump 3 times. If it's too cold for heat pump to work properly it will automatically switch over to gas heat.