If you own a heat pump in Delaware, few things cause faster panic than seeing “Aux Heat” light up on your thermostat in winter. Many homeowners immediately worry about a sky-high electric bill or assume something is broken.
So, what is aux heat, and should you be concerned when it turns on? In most cases, auxiliary heat is doing exactly what it’s supposed to do. But there are times when it can signal a problem that needs attention.
This guide explains what aux heat means, how it’s different from emergency heat, when it’s normal to see it running, and when it’s time to call a professional.
What Is Aux Heat?
Aux heat, short for auxiliary heat, is a secondary heat source built into most heat pump systems, typically in the form of electric resistance heat strips or a gas or oil furnace in a dual-fuel system.
Heat pumps are very efficient, but when outdoor temperatures drop, they can struggle to pull enough heat from the air. When that happens, your thermostat automatically turns on aux heat to help your system keep your home warm.
Why Does Aux Heat Turn On?
Seeing aux heat doesn’t automatically mean trouble. Here are a few common reasons why it may turn on:
- Cold outdoor temperatures: When temperatures dip into the 30s or below, your heat pump may need help maintaining your set temperature.
- Large temperature adjustments: Cranking the thermostat up several degrees at once can trigger aux heat to help the system catch up faster.
- Defrost mode: Heat pumps periodically reverse operation to defrost ice buildup on the outdoor unit. During this short cycle, aux heat keeps warm air flowing inside.
In scenarios like these, seeing the aux heat turn on is normal and temporary.
Auxiliary Heat vs. Emergency Heat: What’s the Difference?
Many homeowners get confused about the difference between auxiliary heat and emergency heat. However, the two settings are very different.
Auxiliary heat turns on automatically and supports your heat pump when needed. It’s used for short periods during cold weather or in defrost cycles, then shuts off.
Emergency heat, on the other hand, must be turned on manually. Activating emergency heat will shut off your heat pump entirely. With that in mind, it should only be used if your heat pump is broken or covered in ice. Using emergency heat unnecessarily can drive up electric bills quickly, especially during a Delaware winter.
When to Be Concerned About Aux Heat
Aux heat becomes a concern when it’s running too often or at the wrong times. You may have an issue if:
- Aux heat runs when it’s 50°F or warmer outside
- Your heat pump is running constantly
- Your electric bill is unusually high in winter
- The system never seems to shut off
- Indoor temperatures still feel uneven or your home never gets warm even when the heat is running
These symptoms can point to problems like thermostat issues, low refrigerant, airflow restrictions, or a heat pump that’s no longer operating efficiently.
Does Aux Heat Cause High Electric Bills in Delaware?
Aux heat uses significantly more electricity than a heat pump alone. Short cycles during cold snaps are expected, but frequent or nonstop aux heat operation can absolutely lead to a high electric bill during a Delaware winter.
If your system relies heavily on aux heat, then it becomes less efficient. Energy costs will also rise, and system components will experience increased wear and tear. That’s why proper system performance and thermostat setup matter so much.
How to Reduce Unnecessary Aux Heat Usage
Here are a few ways you can minimize aux heat usage during the winter:
- Avoid large thermostat temperature jumps
- Keep air filters clean and vents open
- Make sure your thermostat is properly calibrated
- Schedule regular heat pump maintenance
- Address drafts or insulation issues that force the system to work harder
When to Call a Professional for Heat Pump Inspection
You should schedule service if aux heat runs most of the day, turns on in mild outdoor temperatures, coincides with rapidly increasing electrical bills, or appears alongside poor heating performance. A trained technician can determine whether the issue is a simple thermostat fix or a deeper heat pump problem.
Get Peace of Mind This Winter
Seeing aux heat on your thermostat doesn’t have to cause panic. When it’s working properly, it’s simply your system protecting your comfort. But if aux heat seems to run nonstop or your electric bill keeps climbing, it’s time for a professional evaluation.
Call Top Flight Heating, Air, and Plumbing at 302-200-6255 to schedule heat pump repair or winter maintenance services and keep your home warm without unnecessary energy costs.
Frequently Asked Questions About Aux Heat
Read on for answers to some of the most common questions we receive about aux heat.
What is aux heat on a thermostat?
Aux heat is a backup heating source that automatically turns on to help a heat pump during cold weather, defrost cycles, or heavy heating demand.
Is it normal for aux heat to turn on in winter?
Yes. In Delaware winters, aux heat commonly activates during freezing temperatures or while the heat pump defrosts.
Does aux heat mean my heat pump is broken?
Not necessarily. Occasional aux heat use is normal. Constant use may indicate a system issue that needs inspection.
Should I turn off aux heat and use emergency heat instead?
No. Aux heat is controlled automatically and should not be disabled. Emergency heat should only be used if your heat pump fails.
