Despite what their name implies, heat pumps work in cold and hot temperatures, but that doesn’t mean they’ll work optimally in all conditions. One of the problems is a random changeover into AUX mode.
What Is Heat Pump “Auxiliary Heat” Mode?
Is it normal for my heat pump to switch to auxiliary heat in cold weather? Before answering that, you should know how heat pumps actually work.
Heat pumps, like HVAC systems, produce both warm and chilled air, making them ideal for year-long use. In the summer, heat pumps use refrigerant to pull warmth from indoor air. By flipping a switch to reverse the refrigerant flow, they can transfer warmth from the outdoors into your home.
Auxiliary heat refers to the pump’s secondary or backup heat source. Why? If the heat pump’s cold weather operation proves to be ineffective, the system will turn to a gas furnace or electric coil heater to ensure your property can warm up – and that’s AUX mode.
When Does a Heat Pump Use Auxiliary Heat?
If your heat pump thermostat is on its “Heat” setting, it’s running normally. If the unit is on “Aux Heat,” the system is using its backup heat source.
The following situations may be why the heat pump triggers its secondary heater:
Low Outdoor Temperatures
A heat pump in freezing temperatures won’t work as efficiently as in warmer areas, even though the equipment is supposed to keep indoor spaces warm in the winter. These HVAC systems are most effective when temperatures are at or above 32 degrees (freezing point). Temperatures below that will trigger auxiliary functions.
Heat Pump in Defrost Mode
Sometimes, extreme cold can cause a heat pump’s coils to form ice, which hinders heat transfer. Instead, the pump will click into defrost mode, which runs the equipment in its cooling mode for several minutes to help the frozen coils outside thaw. While your heat pump is in defrost mode, it’ll use its secondary heat source to keep your home warm and cozy.
Unsure if your system is in defrost mode? A still fan and steam coming from the heat pump’s outdoor unit are typical signs of frozen coils thawing out.
Thermostat Settings
If your thermostat temperature is two to four degrees higher than indoor temperatures, aux heat will come on. The auxiliary heating will only last until your indoor temperature matches the thermostat settings.
Get Expert Help With Your Heat Pump Today
Is it normal for my heat pump to switch to auxiliary heat in cold weather? For more detailed answers, you can always turn to A-Perfect Climate’s NATE-certified technicians, who have over 35 years of experience providing comprehensive heating and cooling services in Addison, Illinois. We offer efficient HVAC repairs, replacements, and servicing with minimal downtime and lasting results.
Call (630) 691-8380 for an appointment with our A-Perfect Climate professionals!
