Heat Pump/Aux heat Question?

Eliminating the second coil will make your system run longer to achieve the room temperature set. It also means you have half the heating capacity during the very cold nights and may not keep up. The two coils usually means you are closer to 10KW or 12KW heat strips. Removing one coil means you drop it down to 5KW or 6KW. Not too bright given the temperatures in your area.

With one coil, the system will run longer to get your living space up to temperature - but the temperature swings (in the upward direction anyway) will be less noticeable. If anything, you'll actually use less energy running both coils, as the blower won't be running as long. But the house will leak heat at the same rate, one coil or two, and will have to use the same amount of energy generating heat over the day to maintain the settings you put on the thermostat.

Frankly I'm kind of surprised you have a heat pump in Illinois. It gets cold enough to completely negate the heat pump's heating capacity.

The heater is a 15 KW unit so I've been running on 7.5 KW. It's going to get very cold very soon so I'm taking your advice and turning them both on. It seems to me that putting all the load on just one could lead to an early breakdown. THANKS for your input. (actually, my location usually has pretty mild winters. We're only 50 miles from Paducah, KY)

If you are comfortably warm in your house, it's not unreasonable.