What Does Aux Heat Mean on Nest

What Does Aux Heat Mean on Nest


Aux heat on Nest refers to the secondary heating system, which is the backup electric resistance heating in a heat pump. The thermostat inside the house determines when the aux heat is turned on.

This can happen when the primary heat pump struggles to maintain the desired temperature, or when the weather is very cold. If aux heat is constantly running, it may indicate a malfunctioning part in the heat pump or that the thermostat is set higher than normal.

It is important to ensure that the aux heat only runs for the necessary time to meet the temperature setting.

What Does Aux Heat Mean on Nest

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Decoding ‘what Does Aux Heat Mean On Nest’

If you own a Nest thermostat, you may have come across the term ‘Aux Heat’ and wondered what it actually means. In this blog post, we will decode the meaning of ‘Aux Heat’ in the context of Nest thermostats. We will also explore the roles and functions of auxiliary heat, so let’s dive in!

Basic Definition Of Aux Heat In The Context Of Nest Thermostats

In the context of Nest thermostats, ‘Aux Heat’ refers to the auxiliary heating system that works in conjunction with the primary heat source, typically a heat pump. When the outside temperatures drop significantly, heat pumps may struggle to efficiently heat your home. This is where the auxiliary heat comes into play.

The auxiliary heating system in Nest thermostats generally consists of electric resistance heating. Unlike heat pumps that extract heat from the air or ground, electric resistance heating directly produces heat by passing an electrical current through a resistive element.

The Nest thermostat monitors the outdoor temperature and detects when the heat pump alone is insufficient to meet the heating requirements. It then activates the auxiliary heat to provide additional warmth and ensure optimal comfort inside your home. This feature is especially useful during extremely cold weather conditions when the heat pump’s efficiency may decrease.

Roles And Functions Of Auxiliary Heat

Now that we understand the basic definition of ‘Aux Heat’ in Nest thermostats, let’s explore its roles and functions in more detail:

  • Supplementing primary heat: The main role of auxiliary heat is to supplement the primary heat source, primarily the heat pump, during colder temperatures. By activating the auxiliary heat, the Nest thermostat ensures that your home stays warm and comfortable, even when the heat pump alone may not be sufficient.
  • Quick heating response: The auxiliary heating system, being electrical resistance-based, can provide heat more rapidly compared to heat pumps. This quick heating response is particularly useful when you need immediate warmth, such as when you arrive home on a chilly evening.
  • Cold weather resilience: In regions with frigid winters, heat pumps may struggle to extract sufficient heat from the surrounding air. This is where the auxiliary heat system proves its worth by efficiently heating your home even in extremely cold weather conditions.
  • Automatic activation: The Nest thermostat’s intelligent algorithms monitor the outside temperature, indoor temperature, and heating requirements to determine when to activate the auxiliary heat. This automated activation ensures that your home remains cozy without any manual intervention.

In conclusion, ‘Aux Heat’ in Nest thermostats represents the auxiliary heating system that supplements the primary heat source, typically a heat pump. It plays a crucial role in maintaining indoor comfort during colder temperatures and provides quick heating response when needed. With its automatic activation and cold weather resilience, auxiliary heat ensures that your home stays warm and cozy, regardless of the weather outside.

Nest Thermostat Heat Pump Integration

Nest Thermostat provides a seamless integration with heat pump systems, offering advanced control and energy efficiency. With the ability to intelligently manage your heating and cooling, the Nest Thermostat ensures optimal comfort while minimizing energy consumption.

How Nest Thermostat Controls Heat Pump Systems

The Nest Thermostat utilizes smart algorithms and sensor data to effectively control heat pump systems. By monitoring indoor and outdoor temperature, humidity levels, and your preferred schedule, the Nest Thermostat makes precise adjustments to maintain the desired temperature in your home.

When the temperature drops, the Nest Thermostat automatically activates the heat pump to provide heating. It intelligently balances the heat pump and auxiliary heat to ensure efficient operation and avoid excessive energy usage.

Aux Heat Activation Triggers

The auxiliary heat, also known as electric resistance heating, is activated under specific triggers to supplement the heat pump during extreme cold conditions or when rapid heating is required.

Some common triggers for aux heat activation include:

  1. Outdoor temperature below a predefined threshold
  2. Large temperature difference between the desired temperature and actual indoor temperature
  3. Heat pump failure or malfunction

When these triggers are detected, the Nest Thermostat seamlessly activates the auxiliary heat to ensure your home stays warm and comfortable.

It’s important to note that while auxiliary heat can provide quick and powerful heating, it consumes more energy compared to the heat pump. Therefore, the Nest Thermostat intelligently manages the balance between heat pump and auxiliary heat to optimize energy efficiency and minimize costs.

In conclusion, with its advanced integration with heat pump systems, the Nest Thermostat offers precise control, energy efficiency, and optimal comfort for your home.



Optimizing Aux Heat Use

When it comes to your Nest thermostat, understanding the meaning of aux heat and optimizing its use can help you keep your home comfortable while minimizing unnecessary energy consumption. Auxiliary heat, also known as electric resistance heating, is the backup heating system within your heat pump. It is activated by your thermostat when the primary heat source is unable to maintain the desired temperature. However, excessive use of aux heat can lead to higher energy bills. In this section, we will explore strategies to efficiently use auxiliary heat and tips to minimize its unnecessary operation.

Strategies To Efficiently Use Auxiliary Heat

  • 1. Utilize your heat pump’s defrost cycle: The defrost cycle helps remove frost or ice buildup on the outdoor unit, enhancing the heat pump’s efficiency. By allowing the defrost cycle to complete before engaging aux heat, you can maximize the use of your primary heating system.
  • 2. Set temperature differentials wisely: Adjusting the temperature differential, which determines when the aux heat is activated, can help prevent unnecessary use. Keep the differential within a reasonable range to ensure aux heat is only used when necessary.
  • 3. Optimize your thermostat’s learning capabilities: Nest thermostats are designed to learn your schedule and preferences. Take advantage of this feature by providing consistent feedback on your comfort levels. Over time, your thermostat will become more accurate in determining when and how long to engage aux heat.

Tips To Minimize Unnecessary Aux Heat Operation

  1. 1. Proper insulation: Adequate insulation in your home helps prevent heat loss, reducing the reliance on aux heat. Check for any areas of poor insulation and consider adding insulation to improve efficiency.
  2. 2. Weatherstripping: Ensure all doors and windows are properly sealed with weatherstripping to minimize drafts and heat loss. This can help reduce the need for aux heat.
  3. 3. Regular maintenance: Schedule regular maintenance for your heat pump to ensure it operates efficiently. Clean air filters, lubricate moving parts, and check for any potential issues that may affect its performance.
  4. 4. Use zoning systems if available: If your home has a zoning system, take advantage of it. Zoning allows you to control different areas of your home independently, ensuring aux heat is only used in the specific areas that require it.

By implementing these strategies and tips, you can optimize the use of aux heat on your Nest thermostat, leading to improved energy efficiency and reduced heating costs. Remember to regularly monitor your thermostat’s settings and adjust them as needed to ensure optimal comfort while minimizing unnecessary energy consumption.

Nest And Unexpected Aux Heat Activation



When it comes to maintaining a comfortable temperature in your home, your Nest thermostat plays a crucial role. It is designed to optimize the performance of your heating system, including the use of auxiliary heat. However, there might be instances when you notice unexpected activation of the aux heat feature on your Nest thermostat. In this blog post, we will explore the possible reasons behind this and provide you with solutions to common auxiliary heat problems.

Diagnosing Reasons For Unexpected Aux Heat Use

Understanding the reasons behind unexpected aux heat activation can help you address the issue effectively. Here are some potential causes:

  • Extreme outdoor temperatures: When the weather outside is exceptionally cold, your heat pump may struggle to provide sufficient heat. As a result, your Nest thermostat may activate the auxiliary heat to compensate for the shortfall.
  • Malfunctioning heat pump components: A faulty fan motor, bad compressor, or malfunctioning defrost control board can prevent your heat pump from operating efficiently. In such cases, the thermostat may rely on the auxiliary heat as a backup solution.
  • Inaccurate temperature readings: If your Nest thermostat is not calibrated correctly or if it is placed in a location that is not representative of the overall temperature in your home, it may mistakenly activate the aux heat.

Solutions For Common Auxiliary Heat Problems

Fortunately, there are several steps you can take to address unexpected aux heat activation on your Nest thermostat:

  1. Verify temperature readings: Make sure that your thermostat is placed in a central location away from direct sunlight, drafts, or heat sources that may affect its accuracy. Consider using a separate thermometer to cross-reference the temperature readings.
  2. Check for heat pump issues: If you suspect a problem with your heat pump, it is recommended to contact a professional HVAC technician to perform a thorough inspection. They can identify any faulty components and recommend necessary repairs or replacements.
  3. Enable heat pump balance: The Nest thermostat offers a feature called heat pump balance, which allows you to optimize the use of your heat pump and auxiliary heat. By enabling this feature, you can help prevent unnecessary activation of the auxiliary heat.
  4. Regular maintenance: It is essential to schedule regular maintenance for your heat pump system. This includes cleaning or replacing air filters, checking refrigerant levels, and ensuring proper airflow. By keeping your system in good condition, you can minimize the likelihood of aux heat activation.

In conclusion, unexpected activation of the aux heat feature on your Nest thermostat can be a source of frustration. By understanding the possible causes and implementing the suggested solutions, you can ensure efficient and reliable performance from your heat pump system.

Maintaining Your Nest Thermostat

The Nest Thermostat is a smart and efficient way to control the heating and cooling in your home. However, like any other device, it requires regular maintenance to ensure optimal performance. By following a few simple maintenance tips, you can keep your Nest Thermostat running smoothly and extend its lifespan.

Regular Maintenance Tips For Optimal Performance

To keep your Nest Thermostat working at its best, here are some regular maintenance tips:

  • Keep the thermostat clean: Dust and debris can accumulate on the thermostat screen and affect its performance. Use a soft, dry cloth to wipe the screen regularly.
  • Check the batteries: If your Nest Thermostat uses batteries, make sure to check them regularly and replace them if needed. A low battery can cause the thermostat to malfunction.
  • Inspect the wiring: Over time, the wiring connections may become loose or damaged. Carefully inspect the wiring behind the thermostat and ensure that all connections are secure.
  • Update the software: Nest regularly releases software updates for their thermostats. To ensure you have the latest features and bug fixes, keep your thermostat’s software up to date.

Professional Servicing And Support Options

While regular maintenance can go a long way in keeping your Nest Thermostat in top shape, there may be times when professional servicing is required. Nest offers a range of support options to help you with any issues you may encounter:

Online support: Visit the Nest website for FAQs, troubleshooting guides, and helpful articles to answer your questions.
Phone support: If you need more personalized assistance, you can contact Nest’s customer support team via phone. They can guide you through troubleshooting steps or help you schedule a professional service appointment.
Professional servicing: If you prefer to leave the maintenance and repairs to the experts, you can hire a professional HVAC technician or an authorized Nest Pro to service your Nest Thermostat. They have the knowledge and tools to diagnose and fix any issues.

By taking these maintenance tips into account and utilizing the support options provided by Nest, you can ensure that your Nest Thermostat continues to provide you with the comfort and energy efficiency you desire.

Frequently Asked Questions On What Does Aux Heat Mean On Nest

Why Does My Nest Thermostat Say Aux Heat?

Your Nest thermostat says “aux heat” because it is utilizing the backup heating system in your heat pump, known as electric resistance heating. This occurs when the indoor thermostat struggles to reach and maintain the set temperature, indicating a possible issue with the heat pump.

It may be caused by a faulty fan motor, bad compressor, or malfunctioning defrost control board. The auxiliary heat should only run for as long as it takes to meet the desired temperature.

Is It Bad If Auxiliary Heat Comes On?

No, it is not bad if auxiliary heat comes on. The AUX heat setting on an HVAC unit usually turns on when you need heat fast, such as during very cold weather or when the thermostat is set higher than normal.

However, if the auxiliary heat is constantly running or operating for an exceedingly long time, it may indicate a malfunction in the heat pump system.

Why Does My Thermostat Say Aux Heat?

When your thermostat says “aux heat,” it means that your backup heating system, usually electric resistance heating, is being used. This typically happens when your heat pump or the thermostat is having difficulty reaching and maintaining the set temperature. It could indicate a problem with your heat pump, such as a faulty fan motor, bad compressor, or malfunctioning defrost control board.

How Long Should Auxiliary Heat Run?

The auxiliary heat should only run for as long as it usually takes for your home to meet the temperature set on the thermostat.


The “Aux Heat” feature on a Nest thermostat refers to the backup heating system within a heat pump – the electric resistance heating. The thermostat determines when to activate the auxiliary heat, usually when the primary heat source is insufficient.

If your auxiliary heat is constantly running, it may be due to extremely cold weather or a malfunction in the heat pump. It is essential to address any issues to ensure efficient heating and avoid excessive energy consumption.