Why Honeywell Thermostat Says Aux Heat On? Unveil The Reasons!

The Honeywell thermostat displays “Aux Heat” when the auxiliary heat source is activated. This typically occurs when the temperature difference is significant.

When your Honeywell thermostat shows “Aux Heat,” it means the primary heating system needs extra help to reach the set temperature. This can happen when the outside temperature is too low for the main heat pump to efficiently warm your home.

The auxiliary heat setting kicks in to provide additional warmth and maintain comfort in your living space. Understanding why your thermostat displays “Aux Heat” can help you optimize your heating system’s performance and efficiency.

Introduction To Honeywell Thermostats And Auxiliary Heat

When your Honeywell thermostat displays “Aux Heat,” it means the auxiliary heat source is being utilized. Understanding how auxiliary heat works with Honeywell thermostats is essential for efficient heating management.

The Role Of Auxiliary Heat

Auxiliary heat provides additional warmth when the primary heat source is not sufficient to reach the set temperature. It kicks in during extremely cold weather to ensure your home stays comfortable.

Honeywell Thermostat Basics

Honeywell thermostats are designed to regulate your home’s temperature settings. They can control both primary and auxiliary heating systems, ensuring optimal comfort and energy efficiency.

Decoding The ‘aux Heat On’ Message

If you own a Honeywell thermostat, it’s common to see the message ‘Aux Heat On’ displayed on the screen. This message can be confusing to many homeowners and can cause them to wonder if there is a problem with their heating system. In this article, we’ll decode the ‘Aux Heat On’ message and discuss what it means, along with some common misconceptions.

What Does ‘aux Heat On’ Indicate?

‘Aux Heat On’ means that your thermostat has activated the auxiliary heat source in your heating system. This is usually an electric heat strip or gas furnace that is designed to supplement the primary heat source, which is often a heat pump. When the temperature outside drops below a certain level, the heat pump may struggle to keep up with the heating demand, and the auxiliary heat source will kick in to provide additional warmth to your home.

It’s important to note that the auxiliary heat source is more expensive to operate than the primary heat source. This is because it requires more energy to produce heat, so you may notice a higher energy bill when the ‘Aux Heat On’ message is displayed frequently.

Common Misconceptions

There are some common misconceptions about the ‘Aux Heat On’ message that we should clear up:

Misconception Fact
The ‘Aux Heat On’ message means there’s a problem with my heating system. Not necessarily. The ‘Aux Heat On’ message is a normal function of your thermostat and heating system, and it simply means that the auxiliary heat source is active.
The ‘Aux Heat On’ message means my heat pump isn’t working properly. Again, not necessarily. The ‘Aux Heat On’ message is often triggered by the thermostat when the temperature outside drops below a certain level, and the heat pump needs some additional help to keep up with the heating demand.
The ‘Aux Heat On’ message means I need to call a technician. While it’s always a good idea to have your heating system inspected regularly, the ‘Aux Heat On’ message is not necessarily an indication that there is a problem with your system.

Overall, the ‘Aux Heat On’ message is a normal function of your Honeywell thermostat and heating system. It simply means that the auxiliary heat source is active and helping to keep your home warm when the temperature outside drops. If you have any concerns about your heating system, it’s always best to consult with a qualified technician who can help diagnose any issues and recommend the appropriate course of action.

Primary Reasons For Auxiliary Heat Activation

Drops In External Temperatures

When external temperatures plummet, a heat pump’s ability to extract warmth from the air diminishes, triggering the auxiliary heat to provide supplemental warmth. This is especially common in regions experiencing severe winter conditions.

Heat Pump Inefficiency

If the heat pump is not functioning optimally due to issues such as dirt buildup on the coils or low refrigerant levels, the auxiliary heat may engage to compensate for the heat pump’s inefficiency.

Thermostat Settings And Triggers

Incorrect thermostat settings, such as a low temperature differential or a high setback setting, can cause the auxiliary heat to activate unnecessarily. Additionally, the use of emergency heat mode or a malfunctioning thermostat can also trigger the auxiliary heat.

Technical Insights: The Heat Pump And Aux Heat Relationship

Technical Insights: The Heat Pump and Aux Heat Relationship

Heat Pump Functionality

A heat pump is a crucial component of a home’s heating and cooling system. It works by transferring heat from one place to another, providing both warmth in the winter and cool air in the summer. The heat pump operates by absorbing heat from the outdoor air and transferring it inside during the colder months. In the summer, it reverses the process by removing heat from indoors and releasing it outside.

When Aux Heat Complements The Heat Pump

When the outdoor temperature drops significantly, the heat pump may struggle to extract enough heat from the outdoor air to effectively warm the home. This is when the auxiliary heat, also known as “aux heat,” comes into play. Aux heat is typically an electric resistance heating element or a gas furnace that provides additional heating power when the heat pump alone cannot meet the desired indoor temperature.

Troubleshooting Auxiliary Heat Issues

When your Honeywell thermostat displays the “Aux Heat” message, it could indicate potential issues with your auxiliary heat system. Troubleshooting these problems promptly can help maintain a comfortable indoor temperature and prevent energy wastage. In this section, we’ll explore some effective methods for troubleshooting auxiliary heat issues to ensure your heating system operates optimally.

Assessing The Heat Pump Performance

If your Honeywell thermostat is indicating the use of auxiliary heat frequently, it’s essential to assess the performance of your heat pump. Check for any signs of malfunction, such as unusual noises, reduced airflow, or inconsistent heating. Additionally, inspect the outdoor unit for any obstructions or damage that may impede its efficiency.

Checking Thermostat Settings

Incorrect thermostat settings can often trigger the activation of auxiliary heat. Verify that the thermostat is set to the appropriate temperature and heating mode. Ensure that the fan setting is on “Auto” to prevent the constant operation of the auxiliary heat. It’s also crucial to check the programming and ensure that the setback and recovery settings align with your comfort preferences.

When To Call A Professional

If troubleshooting the auxiliary heat issues doesn’t resolve the problem, it may be time to seek professional assistance. An HVAC technician can conduct a comprehensive assessment of your heating system, identify any underlying issues, and perform the necessary repairs or maintenance. Timely intervention by a qualified professional can help prevent further damage and ensure the efficient operation of your heating system.

Impact On Energy Consumption And Bills

When a Honeywell thermostat displays “Aux Heat on,” it indicates increased energy consumption. This setting kicks in when the primary heat source isn’t able to keep up, leading to higher energy bills. Proper maintenance and settings adjustment can help optimize energy usage and reduce costs.

Impact on Energy Consumption and Bills Aux Heat and Increased Energy Use When a Honeywell thermostat displays “Aux Heat,” it means the auxiliary heat feature is activated. This feature kicks in when the temperature inside the house drops significantly and the primary heating system alone cannot maintain the desired temperature.

Auxiliary heat uses more energy compared to the primary heating system, leading to increased energy consumption and higher utility bills. Tips for Energy Efficiency To minimize the impact of auxiliary heat on energy consumption and bills, consider implementing the following energy-efficient strategies:

  • Regular Maintenance: Ensure your HVAC system undergoes regular maintenance to keep it running efficiently and minimize the need for auxiliary heat.
  • Programmable Thermostat: Invest in a programmable thermostat to regulate the temperature based on your schedule, reducing the reliance on auxiliary heat.
  • Insulation: Properly insulate your home to retain heat and reduce the frequency of auxiliary heat usage.
  • Sealing Air Leaks: Seal any air leaks in doors, windows, and ducts to prevent heat loss and decrease the demand for auxiliary heat.
  • Zoned Heating: Consider zoned heating to heat specific areas of your home, allowing you to use less energy and reduce the need for auxiliary heat. Implementing these energy-efficient practices can help mitigate the impact of auxiliary heat on energy consumption and ultimately lower your utility bills.

Preventive Measures And Regular Maintenance

To address the issue of a Honeywell thermostat displaying “Aux Heat,” it is crucial to implement preventive measures and regular maintenance. This can involve checking the system’s settings, cleaning the filters, and ensuring proper insulation to avoid triggering the auxiliary heat unnecessarily.

Regular upkeep helps prevent such errors.

If your Honeywell thermostat says “Aux Heat,” it means that your heat pump’s auxiliary heating system has turned on to provide additional warmth. However, if your thermostat displays this message frequently, it could indicate a problem with your heat pump or thermostat. To avoid this issue, you need to take preventive measures and perform regular maintenance. Here are some strategies that you can follow:

Scheduled Heat Pump Servicing

You need to schedule regular servicing of your heat pump. You should hire a professional technician to inspect your heat pump and perform maintenance tasks. They will clean the coils, check the refrigerant levels, and ensure that all components are working correctly. Regular servicing can help prevent malfunctions and improve the efficiency of your heat pump.

Thermostat Calibration

Your thermostat needs to be calibrated correctly to ensure accurate temperature readings. If your thermostat is not calibrated correctly, it could turn on the auxiliary heating system unnecessarily. You can hire a professional technician to calibrate your thermostat or perform the calibration yourself. You can find calibration instructions in your thermostat’s manual.

Seasonal Preparation Strategies

Before each season, you need to prepare your heat pump for the upcoming weather conditions. For example, before winter, you need to check that your heat pump is working correctly and replace the air filter. You should also check that the outdoor unit is free from debris and that the coils are clean. Before summer, you need to clean the outdoor unit and check that the refrigerant levels are correct. Seasonal preparation can help prevent problems and extend the lifespan of your heat pump.

In conclusion, taking preventive measures and performing regular maintenance can help prevent your Honeywell thermostat from displaying “Aux Heat” frequently. You should schedule regular servicing, calibrate your thermostat, and prepare your heat pump for each season. By following these strategies, you can ensure that your heat pump is working efficiently and effectively.

Advanced Thermostat Features To Manage Aux Heat

When Honeywell thermostat displays “Aux Heat,” it indicates the system is using auxiliary heating to maintain the desired temperature. Advanced thermostat features help efficiently manage auxiliary heat usage for optimal comfort and energy savings. Adjust settings to balance comfort and energy efficiency.

Smart Thermostats And Aux Heat Control

Smart thermostats offer precise control over auxiliary heat, helping optimize energy usage. Auxiliary heat activation indicates the system is using backup heat to reach desired temperatures. Smart thermostats detect when auxiliary heat is necessary and efficiently manage its usage.

Customizable Settings For Optimal Use

Customize thermostat settings to balance comfort and energy efficiency in your home. Adjust settings to minimize the use of auxiliary heat and reduce energy consumption. Personalize temperature thresholds to prevent unnecessary activation of auxiliary heat. Utilize advanced features to create schedules that align with your heating preferences. Incorporating advanced thermostat features can effectively manage auxiliary heat usage for improved energy efficiency and comfort.

Smart thermostats offer customizable settings that allow users to optimize their heating systems and reduce energy consumption. By taking advantage of these advanced features, homeowners can ensure their auxiliary heat is used efficiently and effectively to maintain a comfortable indoor environment.

Conclusion of Balancing Comfort And Efficiency

Key Takeaways On Aux Heat Usage

When using a Honeywell thermostat, the “Aux Heat” message may appear, indicating that the auxiliary heat source is in use to maintain your desired temperature. Understanding when and why this occurs is crucial for optimizing the efficiency of your heating system.

  • Auxiliary Heat Activation: The “Aux Heat” message typically appears when the temperature differential between the set point and the actual temperature is too large for the primary heat source to handle alone.
  • Weather Impact: During extremely cold weather, the auxiliary heat may be activated more frequently to ensure your home remains comfortable, but this can lead to higher energy consumption.
  • Efficiency Considerations: While auxiliary heat provides essential comfort during temperature extremes, it’s important to balance its usage with energy efficiency to avoid unnecessary costs.

Final Thoughts On Smart Heating Solutions

Smart thermostats offer an array of benefits, from energy savings to enhanced comfort. Understanding their functionalities, including the “Aux Heat” feature, empowers homeowners to make informed decisions about their heating systems.

Integrating smart heating solutions allows for precise temperature control, energy-efficient scheduling, and remote access, ultimately leading to a more comfortable and cost-effective living environment.

Frequently Asked Questions

How Do I Get My Honeywell Thermostat Off Aux Heat?

To remove aux heat on your Honeywell thermostat, access the settings and lower the temperature setting.

Why Does My Honeywell Thermostat Keep Going To Aux Heat?

Your Honeywell thermostat may be going to aux heat due to colder temperatures or a malfunction. Ensure proper settings and check for any issues with the thermostat or heating system. Regular maintenance can help prevent frequent aux heat use.

Why Does My Heat Say Auxiliary Heat On?

Your heat says “Auxiliary Heat” when it’s too cold for the primary heat source to keep up.

How To Fix Auxiliary Heat?

To fix auxiliary heat, you must first identify the problem. Check if the thermostat is set correctly, the filter is clean, and the circuit breaker is on. If these are not the issues, it may be a problem with the system’s heat strips or sequencer, which requires professional repair.


Understanding why your Honeywell thermostat displays “Aux Heat” is crucial for efficient heating. By grasping the reasons behind this message, you can ensure your system operates optimally. Stay informed and address any issues promptly to maintain a comfortable and energy-efficient home environment.

Scott Maupin