When the Cold Won’t Quit, We’ve Got Your Back.
It’s freezing outside, your house feels like an icebox, and your thermostat just flashed AUX HEAT—what does that even mean? You just want your home to be warm and cozy, but instead, you’re wondering if something’s wrong with your system, if your energy bill is about to skyrocket, or if your furnace is failing you at the worst possible time.
Take a deep breath—we’ve got you. At B. Carlson Heating, Air Conditioning & Plumbing, we help Albuquerque homeowners stay warm and worry-free, no matter how cold it gets. If you’re seeing AUX HEAT on your thermostat, here’s what it means and what you can do to keep your home comfortable without breaking the bank.
Understanding Auxiliary Heat & How Heat Pumps Work
Auxiliary heat (or aux heat) is your heating system’s way of saying, “I need backup!” If you have a heat pump, it works by pulling heat from the outside air and transferring it inside. This method is incredibly energy-efficient—until temperatures dip too low. When your heat pump can’t extract enough warmth from the freezing air, aux heat steps in to keep your home comfortable.
This extra heat comes from electric resistance heat strips or a secondary gas furnace (if you have a dual-fuel system). It’s normal for aux heat to turn on occasionally, but understanding when and why it activates can help you use it wisely.
When Does Auxiliary Heat Activate?
Your aux heat kicks in when your heating system needs an extra boost. Here’s when that typically happens:
✅ Cold Weather Conditions – When temperatures drop below 35-40°F, your heat pump struggles to absorb enough warmth from the outdoor air. Aux heat provides the extra power needed to maintain your comfort.
✅ Big Thermostat Adjustments – Cranking up the heat by more than 2°F at a time forces your aux heat to activate, using more energy than necessary. Instead, increase the temperature gradually to let your heat pump handle the work efficiently.
✅ Heat Pump Defrost Mode – During especially cold nights, your heat pump can build up frost, making it less effective. To fix this, it periodically switches into defrost mode, briefly stopping heat production. Aux heat kicks in to keep you warm while your system resets.
While aux heat is helpful in short bursts, it’s important to make sure it’s not running all the time.
Is It Normal for Auxiliary Heat to Stay On?
If aux heat only runs occasionally, your system is working as it should. But if it’s on constantly, it could be a sign that something’s not right. Some common culprits include:
❄ Faulty Components – Issues with your compressor, condenser fan motor, or defrost board can make it harder for your heat pump to do its job. When that happens, aux heat has to work overtime.
❄ Low Refrigerant Levels – Your heat pump relies on refrigerant to transfer heat. If it’s running low due to a leak, your system won’t be able to warm your home properly—forcing aux heat to compensate.
❄ Thermostat Problems – If your thermostat isn’t calibrated correctly, it may mistakenly signal aux heat to turn on even when it’s not needed.
If your aux heat is running more than usual, don’t ignore it. Prolonged aux heat use drives up energy costs and puts extra strain on your system. A quick check-up from B. Carlson can help you pinpoint the problem and prevent costly breakdowns.
Does Auxiliary Heat Increase Energy Bills?
Short answer: Yes, it can. Aux heat uses electric resistance heating, which consumes far more energy than your heat pump alone. If it’s running too often, you’ll notice the difference on your utility bill.
💡 How to Minimize Aux Heat Usage:
- Make Small Thermostat Adjustments – Avoid large jumps in temperature. Instead, increase it by 1-2°F at a time.
- Schedule Regular Maintenance – Keep your heat pump clean, tuned up, and working efficiently to prevent unnecessary aux heat usage.
- Improve Home Insulation – Seal leaks, upgrade insulation, and make sure your home retains heat so your system doesn’t have to work as hard.
By following these steps, you can stay warm without running up your energy bill.
Auxiliary Heat vs. Emergency Heat—What’s the Difference?
It’s easy to confuse auxiliary heat with emergency heat, but they serve very different purposes:
🔥 Auxiliary Heat – Turns on automatically when your heat pump needs help. It works alongside your heat pump to provide extra warmth.
🚨 Emergency Heat – Manually activated when your heat pump isn’t working at all. It bypasses the heat pump and relies solely on backup heating (electric resistance or gas furnace). Only use emergency heat if your heat pump fails.
If you ever need to switch to emergency heat, it’s time to call in a professional to diagnose the issue.
Your Best Friend in Home Services.
When temperatures drop and your heating system isn’t keeping up, you don’t have to face it alone. Whether it’s aux heat running too much, a heat pump that won’t work, or an unexplained spike in your energy bill, B. Carlson Heating, Air Conditioning & Plumbing is here to help.
Our expert technicians will diagnose the problem, get your system running efficiently, and ensure your home stays warm all winter long. Call 505-349-4409 to schedule a service appointment today.
B. Carlson Heating, Air Conditioning & Plumbing—Your Best Friend in Home Services.
