Why Does Nest Thermostat Say Aux Heat (Can You Turn It Off)?

Why Does Nest Thermostat Say AuxWhy Does Nest Thermostat Say Aux

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Nest Thermostats are user-friendly, eco-friendly, and in most cases, budget-friendly. But, one thing that can really run up your electric bill is a Nest Thermostat using aux heat.

Here are the main reasons why your Nest Thermostat is using auxiliary heat and how you can turn it off.

How Aux Heat is Effected by Heat Pump Balance Settings

When your Nest Thermostat alerts you that it’s using “aux heat,” whether on the thermostat interface or in the Google Home app, it means it’s using a more expensive secondary heating source.

This is based on your Heat Pump Balance settings.

Consider that the frequency of AUX heating usage depends on your specific system, which may vary between different setups. Some systems might occasionally need AUX heating, while others might rely on it to maintain heating, even when the Max Savings setting is selected.

Here are the options for Heat Pump Balance:

  1. Max Comfort: This is the default setting, where your Nest thermostat prioritizes achieving your desired temperature, even if it means using the costly AUX heat. Max Comfort usually sets a higher AUX lockout temperature, resulting in earlier and more frequent AUX heat use.
  2. Max Savings: Opting for Max Savings aims to minimize the use of AUX heat, maximizing your energy savings. The lockout temperature is set lower, causing AUX heat to turn on later and less frequently.
  3. Balanced: The balanced option enables your heat pump to use AUX heat when necessary. The lockout temperature falls between the values used for Max Savings and Max Comfort.
  4. Off: With Heat Pump Balance turned off, your thermostat relies on the lockout temperature you set to activate AUX heat. You can adjust the AUX lockout temperature in the Settings menu by clicking on the Nest settings icon, then selecting Equipment and Heat Pump.

Although some people worry that their heat pump isn’t working correctly when auxiliary heat is on, it’s usually nothing to worry about — especially if the outdoor temperature is less than 40 degrees Fahrenheit.

If you only see the aux heat alert occasionally and for a short period of time, just wait for it to turn itself off. If it stays on or turns on when the weather is temperate, you may need to turn it off manually or troubleshoot your thermostat. 

How to Turn Off Aux Heat on Nest Thermostat

You can turn off aux heat on your Nest Thermostat using the Google Home app or the thermostat interface.

Before you do, it’s important to remember that auxiliary heat is a useful tool that allows your heat pump to defrost while still heating your home. You should only turn it off manually if you know it doesn’t need to be on.

Follow these steps to turn aux heat off from your Nest thermostat interface:

  1. Open the Quick View menu on your thermostat.
  2. Select “Settings”
    Settings in Nest thermostat
  3. Select “Nest Sense“
    Nest thermostat - nest sense
  4. Select “Heat Pump Balance“
    Nest thermostat - Heat pump balance
  5. Select “Off“
    Nest thermostat - turn heat pump balance off

Disabling Heat Pump Balance means the AUX heat activating solely based on your chosen lockout temperature.

Opting for the lowest setting may prevent the AUX heat from engaging and remove the notification, assuming external factors do not intervene.

How to Turn Off Aux Heat on Nest Thermostat on Nest App

You can conveniently disable the Aux Heat through your Nest App too.

Follow these steps:

  1. Open your Nest App
  2. Select your main thermostat
  3. Select the “Settings” icon in the top right
    Nest app - settings
  4. Select on “Heat Pump Balance“
    Nest app - heat pump balance
  5. Select “On Ready“
    Nest app - heat pump balance on ready
  6. Select “Off“
    Nest app - heat pump balance turned off

Setting the Lockout Temperature on Nest Thermostat

Setting the Lockout Temperature on Nest Thermostat

If you’re reducing how much AUX heat you’re using, consider setting the lockout temperature through your physical Nest Thermostat:

  1. Open the Quick View menu
  2. Select “Settings“
  3. Select “Equipment“
  4. Select “Heat Pump“
  5. Select “Continue“
  6. Then “Continue” again
  7. Select “Heat Pump“
  8. Select your heat pump configuration (Example: 0)
  9. Select “always“
  10. Change the lockout temperature

This is the AUX Lockout Temperature that is controlled by your Heat Pump Balance settings and is the maximum temperature before your AUX heat begins being used.

Now, your thermostat won’t use aux heat unless the outdoor temperature dips below this number.

This is a great way to force your AUX heat on your Nest Thermostat to start kicking in at lower or higher temperatures.

This is common for folks with Nest Thermostats in extreme cold weather who want to change their Heat Pump Balance from the “always” setting.

Why is My Nest Thermostat Using Aux Heat?

There are many things that can cause your Nest Thermostat to start using aux heat. Some are normal, like cold weather or ice build-up on your heat pump.

However, if your thermostat runs for a long time on aux heat or turning it off manually doesn’t work, there may be a bigger problem. 

It’s Too Cold Outside

If it’s just too cold outside for your thermostat to heat your home effectively, aux heat will kick on.

Nest Thermostats connect to the internet and determine when to activate aux heat based on the weather conditions in your area.

Your Heat Pump Needs to Defrost

Temperatures below freezing can cause ice to build up on your heat pump. When this happens, your heat pump needs to focus on defrosting itself. So, your thermostat will automatically switch to aux heat.

It’s best to let things be in this case. As soon as your heat pump is defrosted, it should automatically switch back to traditional heat.

Incorrect Thermostat Settings

Certain Nest Thermostat settings can cause aux heat to kick on more often than it needs to. Check your Heat Pump Balance settings using the steps above.

A Defective Thermostat

On average, Nest Thermostats have a 10-year lifespan. However, if your thermostat is older or defective, it can get permanently “stuck” in aux heat mode.

If you think your thermostat is defective, contact Google Support. If they can’t help you solve the problem, it may be time to replace it. 

FAQ: Nest Thermostat Aux Heat

Is Aux Heat More Expensive?

Aux heat usually runs on either gas or electric power. It can be anywhere from double to five times the cost of running a traditional heat pump.

How Do I Know if My Heating System Has Emergency Heat?

There are two easy ways to tell whether your heating system has emergency heat:

  • If you have your old thermostat, check if there’s an “Emergency” setting, button, or switch.
  • If you set your Nest Thermostat up with an E wire, your system has emergency heat.

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