Honeywell Thermostat Won’t Turn On Heat: How to Fix

So you’ve set your Honeywell thermostat to HEAT for a while now, but it won’t turn on your heating system? If so, keep reading!

In this post, we explain the reasons behind this issue and how to fix it. Let’s get started.

If your Honeywell thermostat won’t turn on heat, here are some reasons this might be happening:

Your thermostat’s wiring is faulty.
The thermostat is installed in the wrong location.
The batteries in your thermostat are weak.
Your furnace is turned off.
Your circuit breaker has tripped.
The thermostat’s temperature sensor is broken.
Your Honeywell thermostat wasn’t correctly configured to your heating system.

That said, let’s look at how to troubleshoot this issue.

Table of Contents

Troubleshooting a Honeywell Thermostat that Isn’t Turning on Heat

1. Inspect the Wiring

If your Honeywell thermostat wires are loose, or not inserted in the right terminals, the device may not turn on your heating system.

So if your Honeywell thermostat won’t turn on heat, the wires might be loose or inserted wrongly. Check and ensure the wires are inserted into the correct terminals.

Every wire in the thermostat is labeled with some letters. Also, the terminals inside the thermostat bear the same letters. Insert each wire in the terminal with matching letters.

Remember to use protective gloves while fixing your Honeywell thermostat’s wiring.

And if you’re not sure how to handle wiring issues in a thermostat, get a licensed professional to check and fix your Honeywell thermostat’s wiring.

If your Honeywell thermostat is still not turning on the heat after trying this fix, continue to the next step.

2. Change the Location of Your Thermostat

Did you install your Honeywell thermostat near an air vent or window? Then you need to change the location.

If the outdoor wind flows around your thermostat, it can affect the device’s temperature readings. For instance, if the outdoor weather is hot, and your room is cool, the thermostat may confuse your room temperature for hot. As a result, the thermostat may turn on the Air Conditioner.

Remove your thermostat from the side of your window and remount it in a location without outdoor airflow.

3. Replace Your Honeywell Thermostat Batteries (If Battery-Powered)

Your Honeywell thermostat requires a voltage of 24V to function effectively. Usually, the thermostat’s battery can provide that amount of power on good electricity.

But as the battery reaches the end of its lifespan, it may weaken and suffer a drop in voltage capacity. As such, the battery might not offer the correct voltage for the thermostat.

If your Honeywell thermostat isn’t getting enough power, it may fail to perform most of its functions, like turning on heat in your home.

To fix this issue, replace the batteries in your thermostat. The replacement batteries for the Honeywell thermostat are alkaline AA or AAA batteries.

Follow these steps to replace your Honeywell thermostat batteries:

Turn off the power on your Honeywell thermostat from its circuit breaker. To switch off your circuit breaker, move the switch to the Off position.
Pull your thermostat’s faceplate from its mounting plate to expose the battery compartment. If your thermostat’s base plate has hinges, you’ll have to unhook the device from the hinges.
Detach the battery compartment from the base plate.
Take out the old batteries from the compartment.
Insert the new batteries in the compartment.
Now, remount the battery compartment to the mounting plate.
Push your thermostat’s faceplate back on the mounting plate.
Finally, switch on your Honeywell thermostat at the circuit breaker to restart the device.

4. Turn On Your Furnace

Your Honeywell thermostat draws heat from your furnace. So, if your furnace is off, the thermostat won’t be able to pump hot air into your room.

Your Honeywell thermostat may not turn on heat in your home because you have accidentally switched off your furnace. You can resolve this problem by turning on your furnace.

But first, you need to ensure that your furnace circuit breaker is still on. If you use an electric furnace, the circuit breaker will most likely be a double-lever breaker. On the other hand, gas furnaces usually have single-lever circuit breakers.

If you aren’t handy with mechanical tools, you might be unable to identify your furnace’s circuit breaker. In this case, you may have to turn on all circuit breakers in your home to discover your furnace breaker. Once you locate your furnace breaker, turn the breaker on.

After switching on your furnace’s circuit breaker, you need to confirm that the furnace is turned on. If the furnace is off, locate the switch on the wall near the furnace and turn it on.

Finally, you should also ensure that the furnace door is closed. Some furnaces may not work if you leave the door open.

5. Switch on Your Thermostat’s Circuit Breaker

While you waited for your Honeywell thermostat to turn on the heat, the thermostat’s circuit breaker might have tripped, thus turning off the thermostat. If you weren’t looking at the thermostat when the circuit breaker went off, you might still think that the thermostat is on.

When your Honeywell thermostat doesn’t pump hot air into your house several minutes after you have turned on the device, check that your thermostat is still on. If not, your thermostat’s circuit breaker may have gone off.

Go to your electrical panel and turn your thermostat circuit breaker back on. If it’s in the ON position, turn it off and then back on.

6. Replace the Temperature Sensor

Your Honeywell thermostat works by assessing the temperature in your home with the aid of a temperature sensor. After measuring the temperature, the thermostat then activates the cooling or heating system in the house to regulate the temperature.

However, if the thermostat temperature sensor is faulty, it might misread the room temperature. And this may not turn on your heating system even when the room temperature is cold.

To determine if your temperature sensor is faulty, use a thermometer to measure the exact temperature of a room. Then, check if the room temperature matches the temperature displayed on the thermostat. If your room temperature differs from the temperature on your Honeywell thermostat, your temperature sensor might be broken.

Buy a new temperature sensor to help your Honeywell thermostat resume proper functioning. You ask your electrician to replace the temperature sensor if you’re not sure of doing it properly.

7. Re-configure Your Honeywell Thermostat

If you recently bought your Honeywell thermostat, the device may not turn on your heating system. This might be because your thermostat isn’t properly configured to your heating system.

Your thermostat needs to learn how your HVAC works. You can resolve this issue by re-configuring your Honeywell thermostat.

Follow these steps to re-configure your thermostat:

Press the button below System. A blank box will appear on the screen.
Hold the empty box until the thermostat displays your thermostat’s model ID.
Tap on the model ID.
Next, select Installer Option.
The system will now request you to enter your Date Code. Locate your Date code at the back of the thermostat.
Your Honeywell thermostat should now display your installation settings.
Now, press and hold the UP arrow and Fan button to start changing your configuration settings.
Your Honeywell thermostat will display the function number 1 and the setting number 0. Function number 1 is for your heating and cooling systems. In contrast, the setting number describes the HVAC system you are using in your home.
Next, there are 5 setting number options under function number 1:
Choose 0 if you use a furnace with your AC (1 is for homes that only use heat pumps).
Choose 2 if you use a heater
Choose 3 if you use a heater with a fan.
Choose 4 if you only want the thermostat to operate your cooling systems.
Navigate through the setting numbers to find the option that describes your HVAC. Once you’ve chosen the correct option, click on Done and Exit the installation settings.

Your thermostat should now turn on your heating system easily.

8. Reset Your Honeywell Thermostat

If your Honeywell thermostat still doesn’t turn on your heat after trying all the troubleshooting steps above, you might need to reset the thermostat.

The process for resetting a thermostat differs from one Honeywell series to another. Here are the steps to follow when resetting some Honeywell thermostat series:

Honeywell 1000 and 2000 Series

Switch off your Honeywell thermostat from its circuit breaker.
Open the thermostat’s cover and remove the batteries.
Insert the batteries in the wrong direction, i.e., place the positive end of the thermostat’s battery on the negative side.
Next, wait for about 10 seconds.
Remove the batteries and insert them in the correct way.
You can now turn on the circuit breaker.

Honeywell 4000 Series

Switch on your thermostat.
Press the Program button three times.
Next, press and hold the Reset button on the thermostat for 5 seconds. You can find the reset button of your thermostat inside a small hole on the front panel of your Honeywell thermostat.
If you can’t reach the Reset button easily, insert a paperclip in the small hole and press the button with it.

If none of the reset methods works for you, refer to your user manual for specific instructions or try googling your Honeywell thermostat model.

Wrapping Up

So that’s how to troubleshoot your Honeywell thermostat that won’t turn on the heating system.

To recap, if your Honeywell thermostat won’t turn on heat, start your troubleshooting with the wiring. Check and fix loose/pinched wires. If that doesn’t work, replace the batteries, change the location, and check that the circuit breaker is on.

You can also perform a factory reset as the last resort. And if the problem persists, contact Honeywell Customer Support for help.

You may also like to see how to troubleshoot relevant issues in Braeburn and Luxpro thermostats.