Nest not turning on heat, and you’re wondering why? Well, this guide covers everything!
If your Nest thermostat doesn’t turn on the heat, then you’re facing a fault either with the unit’s settings or with the HVAC heating system.
So, in this read, we’ll provide you with the steps for a complete HVAC and thermostat inspection, as well as corresponding solutions to the problem.
When your Nest thermostat doesn’t turn on the heat, test whether you can enable the heating manually, and if not, inspect the device’s power supply.
Let’s unwrap more!
Why is the Nest Thermostat Not Turning on Heat?
The most common cause for heating issues with a Nest thermostat is the power supply of your unit and whether the power is sufficient.
Another popular cause is a problem with your HVAC system, so let’s take a closer look at all individual factors involved in the thermostat’s heating.
Here’s what may prevent your Nest thermostat from turning on the heat:
Those factors do not involve severe problems with the HVAC system, but all of them can be checked at home, even if you’re not a technician.
So, let’s continue with the solutions below!
How to Fix When Nest Not Turning on Heat in Easy Steps?
Tip: Follow the steps chronologically!
1. Turn ON the Nest *Heat* Manually
The first and essential step to undertake is to test whether the Nest thermostat will enable the heating manually through the app.
The feature is called “Emergency Heating” and is located in the Nest app settings, so you must attempt to turn the heating manually to check if it will work.
How to Turn on Nest Emergency Heating?
- Open the Nest Home app.
- Select the Nest thermostat.
- Tap “Settings Thermostat.”
- Press on “Emergency Heat.”
- Tap the switch to turn it ON.
So, there are two possible scenarios, so let’s conclude:
- If your Nest thermostat turns on the heating manually, then there is no power problem, and your HVAC system is working correctly.
- If your Nest thermostat won’t turn on the emergency heating, there is a power-related issue, or the HVAC heating installation is not working.
Note: If your Nest thermostat’s emergency heating is working, but the automated (scheduled) heating is not turning on, verify there are no logical conflicts.
2. Inspect the Nest Thermostat Power
The electrical supply of your thermostat is one of the most critical factors for the heating and cooling functionalities.
Your Nest thermostat is powered by the “C” wire, which is hooked to the electrical installation or uses replaceable AAA batteries if you have the standard thermostat.
So, you must verify that the power supply to your thermostat is working, or the battery will get low, and the thermostat will shut down essential features.
The features that will go off first include the heating, cooling, thermostat display, and schedules.
Power Check: Google Nest Thermostat
The Google Nest Thermostat uses two AAA batteries, and whenever the charge is low, the thermostat may not enable the heating/cooling.
So, one of the most effective ways to solve the issue would be to reinsert the batteries or entirely replace them with a fresh pair of batteries.
Note: Only use high-quality batteries for your Nest thermostat.
Power Check: Nest Learning or Nest E
The Nest Learning and Nest E Thermostats use an in-built (rechargeable) battery, and you can manually change the thermostat anytime.
So, to verify that the thermostat is charged and the power is not insufficient, unmount the faceplate from the wall and locate the USB-C input port.
Tip: You can charge the Nest thermostat by using a USB adapter or plugging it into your PC!
3. Reset Power from the Main Circuit
If your Nest thermostat is not turning on the heating, the next step is to restart the power from the main circuit breaker.
This will reboot the entire thermostat installation, provide a fresh current, and hopefully, the thermostat’s heating issue will disappear.
To restart the power from the primary circuit, follow the steps below:
- First, go over to the primary electrical circuit.
- Open the cover to expose the fuses/switches.
- Flip the switches on all fuses down to “OFF.”
- Wait for a few minutes and flip the switch up.
This will reset the power of your entire home, including the Nest thermostat HVAC system, and will probably solve most of your problems.
However, remember that the Nest thermostat may not turn on immediately, so you must remain patient until the Nest thermostat enables the heat.
Tip: Before disconnecting the power, we recommend turning off and unplugging your appliances.
4. Clean the HVAC System Air Filter!
The heating may not work on your Nest thermostat because of an issue with the HVAC system, and one of the most prevalent causes is a clogged air filter.
When the airflow is obstructed or not working entirely, you may be unable to turn on the heat and cause damage to the system.
Where is the Air Filter?
The air filter of your HVAC system is located in the furnace’s compartment and can be easily removed by undoing the screws. Verify to preserve the screws to use them later for mounting.
How to Clean Air Filter?
The air filter is an electrical-free component, so you can use water to clean anything clogging the air, such as dust/dirt accumulation.
We recommend using lukewarm water and a vacuum to suck anything clogging the airflow and wait until the filter is completely dry before installing it.
Tip: Check and clean your air filter twice a year!
5. Verify the Furnace’s Door is Closed
Your Nest thermostat heat not turning on when the HVAC furnace door is not fully closed or the switch hasn’t clicked in.
Hence, you need to check whether something is obstructing the door, preventing the switch from making contact, or find out if the switch is broken/defective.
One More Thing – the Heating Boiler!
The heating bolier/s in the HVAC system are responsible for the heat function of the thermostat, and when something is wrong, the mode won’t function.
Hence, you must inspect this as well.
Here’s how to inspect your heating boiler:
- First, locate the heating boiler in your HVAC system.
- On the back, locate the temperature control module.
- Rotate the switch to increase the water temperature.
- Try to identify whether the boiler pipes are clogged.
If you discover any defects, especially with the water pipes, know that the heat may not work as long as the problem is present.
For issues with the HVAC system, we recommend contacting a technician for a qualified inspection and professional troubleshooting.
Alert: Interact with the boiler’s pipes or wires only after disconnecting the main power supply!
6. Factory Reset Your Nest Thermostat
If you cannot discover any issues with the HVAC system, but the Nest thermostat is not turning on the heat, perhaps it is a system-related problem.
So, the next step by importance would be to perform a factory reset, which will initialize the system of the Nest thermostat to factory defaults.
Warning: The factory reset will unpair your thermostat from the Nest app!
Here’s how to factory reset the Nest thermostat in easy steps:
- Pull out the Quick View by pressing the Ring.
- Go to “Settings” and enter the “System” tab.
- From there, reveal “All Settings” and “Reset.”
- Finally, confirm the reset and select “Reset.”
The Nest thermostat will now reset to factory defaults, and when the process is over, the device will automatically restart.
Then, you will have to carry out the initialization, and when you finish the setup, the heating of your Nest thermostat should start working.
Note: The factory reset doesn’t require an internet connection and lasts about 3 minutes!
Hence, whenever your Nest not turning on heat, you must first attempt to manually turn on the heat and inspect the thermostat’s power supply.
If everything is working correctly, check if the air filter is clogged, if the furnace is closed, and factory reset the thermostat.
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Kevin has over five years of experience working in various Tech startups and providing Technical solutions. He has contributed to many Tech publications and websites.