Is It Bad If Auxiliary Heat Comes On

Is It Bad If Auxiliary Heat Comes On?

Last Updated: February 26, 2024By

Auxiliary heat, also known as emergency heat or supplemental heat, is a feature found in many heating systems, particularly heat pumps. While its primary function is to provide additional warmth during frigid weather or when the primary heating source can’t meet demand, there is often confusion about whether its activation is a cause for concern. In this article, we’ll explore the functionality of auxiliary heat and address the question: Is it bad if auxiliary heat comes on?

What is Auxiliary Heat?

Auxiliary heat, also known as emergency heat or supplemental heat, is an additional heating source integrated into many heating systems, particularly heat pumps. Its primary function is to provide extra warmth during icy weather conditions or when the primary heating source, typically a heat pump, cannot meet the desired indoor temperature requirements. The heating system often automatically activates auxiliary heat when outdoor temperatures drop below a certain threshold, ensuring the home remains comfortable and adequately heated. It typically consists of electric resistance coils or a backup furnace that generates heat to supplement the heat pump’s efforts. Auxiliary heat is crucial in maintaining indoor comfort and ensuring homes remain warm and cozy, especially during harsh winter.

How Do Heat Pumps Work?

Heat pumps transfer heat from one place to another using a refrigerant cycle. Here’s a simplified explanation of how they operate:

  • Heat Absorption: In heating mode, the heat pump’s outdoor unit (the evaporator coil) absorbs heat from the outside air, even in cold temperatures. This process is possible because there’s still heat energy in the air, even when it feels hard.
  • Refrigerant Circulation: The absorbed heat energy causes the refrigerant inside the evaporator coil to evaporate into a gas form. The gas then travels through a compressor, which increases its temperature and pressure.
  • Heat Release: The hot, pressurized refrigerant gas flows into the indoor unit (the condenser coil), releasing its heat energy into the indoor air. As a result, the indoor air becomes warmer.
  • Cooling Cycle: In cooling mode, the process is reversed. The heat pump absorbs heat from indoor air and releases it outside, effectively cooling the indoor space.
  • Circulation and Regulation: Throughout this process, a circulating fan distributes the heated or cooled air throughout the building, and a thermostat regulates the temperature by signaling the heat pump to cycle on or off as needed.

How Do Heat Pumps Work?

Auxiliary heat is a supplemental heating source in heating systems, particularly those equipped with heat pumps. Here’s how auxiliary heat works:

  • Activation: When the primary heating source, typically a heat pump, is unable to adequately heat the home due to frigid outdoor temperatures or other factors, the auxiliary heat is activated automatically by the heating system.
  • Heat Generation: Auxiliary heat often consists of electric resistance coils or a backup furnace. When activated, these heating elements generate additional heat to supplement the heat pump’s efforts in warming the indoor space.
  • Supplemental Heating: The generated heat from the auxiliary source is distributed throughout the home via the ductwork or other heating distribution system, providing supplemental warmth to maintain the desired indoor temperature.
  • Efficiency Considerations: While auxiliary heat ensures comfort during extreme weather conditions, it is typically less energy-efficient than the primary heat pump. Therefore, monitoring its usage and addressing any issues that may lead to excessive reliance on auxiliary heat, such as system malfunctions or inadequate insulation, is vital.

Factors Influencing Auxiliary Heat Activation

Several factors can influence the activation of auxiliary heat in heating systems. Understanding these factors is essential for homeowners to optimize the efficiency of their heating systems and minimize energy consumption. Here are some key factors:

  • Outdoor Temperature: Auxiliary heat is often activated when outdoor temperatures drop significantly. Heat pumps become less efficient in extracting heat from the outdoor air as temperatures decrease, starting auxiliary heat to supplement heating.
  • Heat Pump Efficiency: The heat pump’s efficiency can impact the frequency of auxiliary heat activation. Older or poorly maintained heat pumps may struggle to meet heating demands efficiently, resulting in more frequent activation of auxiliary heat.
  • Insulation and Home Sealing: Inadequate insulation or air leaks in the home can lead to heat loss, causing the heat pump to work harder to maintain indoor temperatures. This increased workload may trigger the activation of auxiliary heat more frequently.
  • Thermostat Settings: Improper thermostat settings or programming can influence auxiliary heat activation. If the thermostat is set too high or programmed inefficiently, it may cause the heat pump to run less effectively, leading to more frequent use of auxiliary heat.
  • System Malfunctions: Malfunctions within the heating system, such as faulty sensors, refrigerant leaks, or compressor issues, can disrupt the heat pump’s operation and prompt the activation of auxiliary heat.
  • Heat Pump Size and Capacity: The heat pump’s size and capacity relative to the home’s size can affect its ability to maintain indoor temperatures efficiently. An undersized heat pump may struggle to meet heating demands, leading to more frequent auxiliary heat activation.

By considering these factors and addressing any issues that may contribute to excessive auxiliary heat activation, homeowners can optimize the performance of their heating systems and minimize energy consumption and costs. Regular maintenance, proper insulation, and efficient thermostat management are critical strategies for reducing the reliance on auxiliary heat and maximizing overall system efficiency.

Is It Bad If Auxiliary Heat Comes On?

Activating auxiliary heat in a heating system is not inherently wrong, but it can indicate potential issues that warrant attention. While auxiliary heat is crucial in ensuring indoor comfort during extreme cold weather conditions or when the primary heating source, typically a heat pump, cannot meet demand, its frequent or prolonged activation may suggest underlying problems.

Excessive reliance on auxiliary heat can lead to higher energy consumption and utility costs. The activation of auxiliary heat may indicate inefficiencies in the heating system, such as malfunctions, inadequate insulation, or improper thermostat settings. Addressing these issues through regular maintenance, insulation improvements, and efficient thermostat management can optimize performance, minimize auxiliary heat usage, and ensure energy-efficient operation. This is a valuable indicator for homeowners to assess and improve their heating system efficiency.

How Do I Stop My Auxiliary Heat from Coming On?

To prevent your auxiliary heat from coming on unnecessarily, there are several steps you can take:

  • Thermostat Settings: Ensure your thermostat is set to an appropriate temperature range for heating and cooling modes. Avoid setting the thermostat significantly higher than necessary during cold weather, as this may trigger auxiliary heat unnecessarily. Additionally, utilize programmable thermostats to schedule temperature adjustments based on your daily routines and outdoor weather conditions.
  • Thermostat Programming: If your thermostat offers programming capabilities, use features such as adaptive recovery or intelligent scheduling, which optimize heating cycles and minimize the need for auxiliary heat.
  • Insulation and Sealing: Improve insulation in your home and seal any air leaks to minimize heat loss. Proper insulation and sealing can help the heat pump operate more efficiently, reducing the likelihood of auxiliary heat activation.
  • Regular Maintenance: Schedule regular maintenance checks for your heating system to ensure it operates at peak efficiency. Professional maintenance can help identify and address issues that may lead to unnecessary auxiliary heat usage, such as sensor malfunctions or refrigerant leaks.
  • Upgrade to a More Efficient System: Consider upgrading to a more energy-efficient heat pump or heating system. Newer models often come with advanced features and improved efficiency, reducing the reliance on auxiliary heat.
  • Consult a Professional: If you cannot determine the cause of excessive auxiliary heat activation or suspect underlying issues with your heating system, consult a professional HVAC technician. They can thoroughly inspect, diagnose problems, and recommend appropriate solutions to minimize auxiliary heat usage.

By implementing these strategies, you can effectively reduce the need for auxiliary heat and optimize the efficiency of your heating system, ultimately saving energy and lowering heating costs.

Signs Your Auxiliary Heating System is Malfunctioning

Several signs can indicate that your auxiliary heating system is malfunctioning, requiring attention and potential repairs. These signs include:

  • Frequent Activation: If your auxiliary heat is activating more frequently than usual, it could indicate underlying issues with your primary heating system, such as a heat pump malfunction or insufficient heating capacity.
  • Inadequate Heating: If your home is not reaching the desired temperature despite the auxiliary heat being on, it may suggest that the system is not functioning correctly or cannot meet heating demands effectively.
  • Uneven Heating: Uneven heating throughout your home, with some areas feeling significantly colder than others, may indicate problems with your heating system, including issues with ductwork, airflow, or heat distribution.
  • Strange Noises: Unusual noises such as banging, clanging, or grinding from your heating system could signal mechanical problems or component failures within the auxiliary heat source or the heating system.
  • Increased Energy Bills: A sudden spike in energy bills without a corresponding increase in heating usage may indicate inefficiencies or malfunctions within your heating system, including auxiliary heat components.
  • System Errors or Malfunctions: If your thermostat displays error codes or malfunctions when operating your heating system, it could indicate underlying issues that require attention from a professional HVAC technician.
  • Burning Smells or Strange Odors: Unpleasant odors, mainly burning smells, emanating from your heating system can indicate overheating or electrical issues within the auxiliary heat source or other components.
  • Tripped Circuit Breakers: If your circuit breaker repeatedly trips when the auxiliary heat is in use, it may suggest electrical problems or overload issues within the heating system.

If you notice any of these signs, you must address them promptly by contacting a qualified HVAC technician. Ignoring potential malfunctions or inefficiencies in your auxiliary heating system can lead to further damage, increased energy consumption, and compromised indoor comfort. A professional inspection and repairs can help restore your heating system’s functionality and ensure efficient operation throughout the colder months.


Why Does My Auxiliary Heat Come On Even When It’s Not Very Cold Outside?

Auxiliary heat may activate in mild weather conditions if your heat pump is experiencing issues such as refrigerant leaks or sensor malfunctions. It could also indicate inadequate insulation in your home, causing the heat pump to struggle to maintain indoor temperatures efficiently.

Is It Normal For My Auxiliary Heat To Run For Extended Periods?

While auxiliary heat is designed to supplement your primary heating source during cold spells, prolonged activation may suggest underlying problems with your heating system, such as a malfunctioning heat pump or inadequate heating capacity. It’s advisable to have a professional inspect your system if auxiliary heat runs excessively.

Can I Manually Control When The Auxiliary Heat Comes On?

Most modern thermostats are programmed to activate auxiliary heat automatically when needed based on temperature differentials. However, some thermostats may offer an emergency heat setting that allows you to engage auxiliary heat, if necessary, manually. Refer to your thermostat’s user manual or consult a professional for manual control options.

Will Using Auxiliary Heat Significantly Increase My Energy Bills?

While auxiliary heat is typically less energy-efficient than the primary heating source, its impact on energy bills depends on system efficiency, insulation levels, and thermostat settings. Excessive reliance on auxiliary heat due to system malfunctions or inefficiencies may increase energy consumption and utility costs.

How Can I Troubleshoot Auxiliary Heat Issues On My Own?

Basic troubleshooting steps for auxiliary heat issues include checking thermostat settings, inspecting air filters for blockages, and ensuring that outdoor heat pump units are debris-free. However, for more complex issues or unsure, it’s best to contact a qualified HVAC technician for professional diagnosis and repairs.


Understanding auxiliary heat’s function and potential issues is crucial for homeowners to optimize the performance of their heating systems. While it serves as a supplement to primary heating during cold weather, activation can indicate underlying issues. Addressing inadequate insulation, thermostat settings, and system malfunctions can minimize auxiliary heat usage and ensure energy-efficient operation. Regular maintenance, repairs, and professional inspections are essential for optimal performance and indoor comfort. Proper care can lead to reliable and efficient heating in homes.

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Monique Valeris

Monique Valeris is a prominent house editor with a keen eye for design and a passion for creating warm and stylish interiors. With a wealth of experience and a fresh perspective, she blends contemporary trends with timeless elements to create aesthetically pleasing and functional spaces. Valeris's editorial contributions extend beyond the printed page, engaging with her audience through various platforms to share insights and tips. Her ability to effortlessly blend different design styles and her dedication to promoting inclusivity within home aesthetics set her apart as a leader in the field.