Thermostat Says Heat On but No Heat (Why & How To Solve It)

Heating is essential for the chilly seasons. If you head over to your thermostat that says it’s heating but no heat is coming out of the vents it can be frustrating, especially if you are freezing. You should take a step back to see what might be the problem so you can get your heater up and running. It’s likely not your fault and something that can be fixed quickly.

Most of the time when a thermostat says it is on heat but no heat comes out you’ll be able to change the settings or clean something to get it back on. There are various things to check on your thermostat before you need to call for professional help. Thermostats are quite sensitive and can fail due to small issues that are unavoidable.

Is It a Thermostat Issue?

Most times the thermostat will be the issue but sometimes it won’t be. You should first check your thermostat to see if that is the issue before moving on to a different part of the system. This way you won’t waste any more time freezing than you need to.

Knowing that the issue is with the thermostat is important because if the issue is not with the thermostat then it may be time to call a professional for help. Meaning that you may be cold just a little while longer. The heater itself is a complex system that would require tools and expertise to fix.

The reason why you would need to call a professional is that if the heating system is the issue, the fix could be anywhere from needing to flush out drain lines to checking the chimney exhaust flue. Those tasks may be too dangerous or require tools that you don’t have. 

There are a lot of troubleshooting tips you can follow to help you, such as cleaning, making sure certain things are on or off, or doing small replacements. Everything that you can do as a homeowner for your heating system is unfortunately small if the problem happens to be big. Usually, the case is that you just need to clean something or have the wrong setting on.

Why am I Not Getting Heat?

There are several reasons that you are not getting heat when you turn your thermostat on. After going through the possible issues you should try the easy ones first. If your heat is still not turning on after trying the easy troubleshooting problems then you should try the harder ones or call someone to help you through it. This way you’ll get heat in your home as soon as possible.

Filter is Dirty

One possibility you are not getting heat is that your filter is dirty. If your filter is dirty this likely means it is clogged. When you have a dirty filter your heater will not turn on because it could cause a fire.

Keeping your filter clean is also important because it will ensure your furnace is always operating at its highest function. A dirty filter means that it is not pushing through as much heat as it could be and thus making its operating cost go way up.

If your filter is dirty then you should go ahead and replace it. After you replace it your heater should be up and running. Try to replace your heater’s filter every month.

Gas Supply is Turned Off

There are two main types of heaters such as a heater system that runs through your whole house connected to a furnace or a wall heater. 

It is common for those who have a wall heater to turn off the pilot light when it is spring and to light it again in the fall. If you have a wall heater and your pilot isn’t lit then you’ll need to light it.

If you live in a home then you need to follow the gas line from your furnace to the meter. The handle should be parallel to the gas pipe. If it is not them turn it so it is.

Heater is Cut Off From Power Source

Just like most of the appliances in your home, a heater requires power. Without a power source, it will not turn on. Although it may be connected to gas, electricity is still required for the heater to run.

It is easy for someone to turn it off and then forget about it.

Thermostat is on Wrong Setting

Sometimes we overlook things. Such as the settings on the thermostat. Some thermostats nowadays are hard to program or navigate through. Y

You may have accidentally put it in auto or eco mode when really you want heat. If that is the case then you should try to look up how to set your thermostat to heat.

You should also check to see if the temperature is high enough to ignite the furnace. If your thermostat is set to heat but the temperature set is lower than the temperature in the house the furnace will not turn on.

Pilot Igniter is Dirty

A more difficult task is to see if the pilot igniter is dirty and needs to be completely cleaned. This is because this would require professional help.

To check if it is dirty you first need to turn off the power that is in the panel connected to your furnace so that you do not accidentally harm yourself. Then you will want to take the panel of your furnace off which may require a screwdriver.

If you see that it is dirty, then it is time to call someone out to clean it out.

Sensor is not Working

The sensor of a heater is there to sense whether it needs to turn on or not after you have set the temperature you wish it to be. Sensors work by increasing voltage and in turn, this directly increases the heat. If the sensor is not working then it will not increase voltage and no heat will come out.

If your sensor is the reason why the heater is not working then you will have to call a professional to help fix it because the sensor has to be fixed by replacement. It is possible to do it yourself but it would be safer for an expert to replace it.

Battery is low

Some thermostats don’t last forever and may need a battery replacement. If you have an older thermostat and a battery starts to flash in the corner of the screen or give any indication that it is out, then you will have to replace the batteries.

This may take some time going to get the batteries if you don’t already have them, but it is one of the easier fixes.

Furnace is short-cycling

If your furnace is short-cycling then it is likely that it has turned on and off or has gone through a few cycles without blowing any heat through your home. The short cycling could be caused by problems with the blower, a wrong furnace size, or a dirty filter. 

Since there are a lot of potential issues that could cause furnace short-cycling it would be best to call a professional that can come out quickly to asses and fix what is wrong.

Venting is clogged

If your venting is clogged there are a few ways to tell. First is that some of the rooms in your home have different temperatures. Maybe one room is heated but the next few are not. You can also tell by dust coming from the vents or by a higher utility bill than usual. 

The easiest way o fix a clogged vent is by calling a professional that can vacuum and clean out the vent ducts so that they can blow clearly.


Although it may be frustrating when you are freezing and your thermostat says there is heat but no heat comes out, there are several ways you can check and get help so that you can get heat as soon as possible. 

Going through a checklist of methods from what is the easiest fix to the hardest will help you get through dealing with a potentially malfunctioning thermostat or heater.

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