Auxiliary heat is a backup heating system that kicks in when your main heat pump can’t keep up—usually because it’s too cold outside or the pump needs a quick boost.
Most people never think about it until they see “Aux Heat” on the thermostat and worry their bill is about to jump. In everyday life, it just quietly turns on during cold snaps so your house stays warm. If you hear the unit switch to a louder hum or feel extra-warm air, that’s probably auxiliary heat doing its job.
Meaning & Usage Examples
Think of it as an electric space heater built into your HVAC. Example: “The forecast says 15 °F tonight, so expect auxiliary heat to run for a while.” Another: “I set the thermostat up three degrees, and auxiliary heat fired up to reach the new setting faster.”
Context / Common Use
You’ll notice it most when the outdoor temp drops below about 30 °F, when you raise the thermostat more than 2–3 degrees at once, or when the heat pump is in defrost mode. It’s normal, but if it runs nonstop, check your filter or call a tech.
Does auxiliary heat cost more?
Yes, it uses more electricity than the heat pump alone, so short bursts are fine; long runs will raise your bill.
How do I know it’s on?
Most thermostats show “AUX,” “Aux Heat,” or a small flame icon when it’s active.
Leave a Reply