What Is Auxiliary Heat? Your Complete Guide
Auxiliary heat is a supplemental heating feature in heat pump systems that provides additional warmth when the primary system cannot maintain the desired temperature on its own. This typically happens during very cold weather, when the heat pump struggles to extract enough warmth from the outside air.
Understanding how and when auxiliary heat activates is key to managing your home's comfort and energy costs. This guide breaks down everything you need to know about this essential feature. heat pump systems gas furnaces
What Triggers Auxiliary Heat to Turn On?
Auxiliary heat automatically activates to maintain indoor comfort when outdoor temperatures drop to a point where the heat pump's efficiency decreases, often around 30°F to 35°F. At these lower temperatures, the heat pump may not be able to extract enough heat from the air to meet your thermostat's setting.
Other factors can also trigger the auxiliary heat:
- Rapid Temperature Changes: If you increase the thermostat setting by several degrees at once, the system may use auxiliary heat to reach the new temperature faster.
- Defrost Cycle: When frost builds up on the outdoor unit, the heat pump will enter a defrost cycle. During this time, it temporarily reverses operation, and auxiliary heat may turn on to prevent cold air from blowing inside your home.
- High Humidity: In some conditions, a heat pump may struggle to both dehumidify and heat the air effectively, requiring backup heating to manage indoor comfort.
“Auxiliary heat adds an extra layer of protection to a home’s heating system, particularly for homeowners in extremely cold climates where a standalone heat pump may need some added power during a cold spell, “ Melissa Frause, owner of Bob’s Heating and Air Conditioning in Woodinville, WA, said.
How is Auxiliary Heat Different from Emergency Heat?
It's crucial to understand the distinction between auxiliary heat and emergency heat to use your system efficiently.
- Auxiliary Heat is a supplemental source that works with your heat pump. It turns on automatically for short periods when the heat pump needs an extra boost to maintain your desired temperature. This cooperative function is a normal part of your system's operation in cold weather.
- Emergency Heat is a manual backup setting used only when the primary heat pump system fails or is not functioning properly. It relies entirely on a secondary heat source, usually electric resistance coils, which consumes significantly more energy. You should only activate emergency heat in a true system failure and contact a professional for repairs.
Using emergency heat for extended periods can lead to a substantial increase in your energy bills. Auxiliary heat, while less efficient than the heat pump alone, is more cost-effective than emergency heat because it only supplements the primary system.
Do I Need an Auxiliary Heat System?
Whether you need auxiliary heat depends heavily on your local climate.
- Mild Climates: In areas with mild winters, a high-efficiency heat pump may be sufficient on its own.
- Cold Climates: In regions where temperatures frequently drop below 35°F, an auxiliary heat system is essential to ensure consistent comfort.
Many modern heat pumps have integrated electric resistance heating elements that serve as the auxiliary source. Another powerful and efficient option is a dual-fuel system, which pairs a heat pump with a gas furnace. In this setup, the heat pump acts as the primary source, and the gas furnace takes over as the auxiliary heat when temperatures become too cold for the heat pump to operate efficiently.
“Families with young kids or elderly residents may find that having auxiliary heat provides peace of mind during unpredictable weather conditions,” Frause said.
It’s worth considering your local climate and consulting your local Bryant dealer to determine whether additional auxiliary heat is necessary for your home.
Troubleshooting Your Auxiliary Heat
If you notice your auxiliary heat is running too often, it could signal an issue. Key indicators include:
- An unexpected and significant increase in your energy bills.
- Your system runs constantly but struggles to warm your home.
- The "AUX" or "EM" light on your thermostat is on frequently, even in mild weather.
- Unusual noises, like banging or grinding, coming from your HVAC system.
If you experience these signs, it's time to call an expert. A qualified professional, like your local Bryant dealer, can diagnose the problem and ensure your system operates safely and efficiently.
Regular HVAC maintenance is the best way to keep your entire system, including the auxiliary heat, in optimal condition.
Bryant Solutions for Efficient Heating
Bryant delivers innovative solutions designed for exceptional performance, even in the coldest conditions. Our lineup includes advanced cold climate heat pumps that optimize heating efficiency, keeping your home warm and your energy bills low.
Pair your system with a smart thermostats to unlock even greater control. These thermostats allow you to program schedules, adjust settings remotely, and monitor energy use, helping you manage your auxiliary heat effectively and maximize comfort.
Connect With A Bryant Dealer on Auxiliary Heating
A Bryant expert can help you understand the benefits of adding a gas furnace or other auxiliary heating sources to your system, ensuring you stay comfortable no matter how cold it gets outside. They will guide you in selecting the right equipment based on your home's heating needs and provide professional installation and service. Schedule an appointment with your local Bryant dealer today to discuss how auxiliary heating can improve your home's comfort and efficiency.
FAQs On Auxiliary Heat
Auxiliary heat activates when your heat pump can’t keep up with the heating demand, usually in very cold weather or during a defrost cycle.
Yes, auxiliary heat is typically more expensive to run because it relies on electric resistance heating, which uses more energy than the heat pump.
Auxiliary heat should come on only occasionally, such as during extremely cold temperatures or when the system is trying to raise the temperature quickly.
Yes, it’s okay to run auxiliary heat when needed, but it should be temporary—if it runs frequently, it could indicate a problem with your heat pump.
If auxiliary heat runs too long, it can lead to high energy bills, system wear, and may signal that your heat pump is undersized or malfunctioning.
Auxiliary heat is a backup heating feature in heat pump systems that uses electric resistance or a furnace when outdoor temperatures drop too low for efficient heat pump operation.
No, it’s normal during very cold weather or rapid temperature recovery. Frequent use in mild weather, however, may indicate a system issue.
Typically, auxiliary heat activates when outdoor temperatures fall near or below freezing, or when the system can’t maintain the set temperature efficiently.
It turns on automatically when the heat pump can’t meet the thermostat’s demand, such as during extreme cold or defrost cycles.
It’s not recommended—aux heat is meant for temporary use and is less efficient than standard heat pump operation.
It should only run as needed during temperature drops or system defrosts, not continuously.
Yes. The system activates it automatically based on outdoor temperature and thermostat demand.
