Why My Gas Heater Furnace Keep Shutting Off – [Quick Solution]

We all know what it’s like to relax with the heater on and all of a sudden, it shuts off. Nothing is worse than having to suffer through the cold without a heater. If this happened to you and you did not know what to do, it’s okay. I will go through a list of common problems that cause heaters to shut off and what you can do about them. So, without further ado, let’s take a look.

Problem: Air Filter

The point of air filters is to keep the air clean, but after constant use, they are likely to get clogged or otherwise dirty. When the air filter is not in good shape, it cannot properly filter the air. On top of that, the heat exchanger will not be able to receive any air. As a result, the heat exchanger will get too hot and the heater will switch off as a safety measure.

This is typically the first area examined when a heater keeps switching off. This is because it is very common and can easily be fixed.


If you’ve inspected your heater and found the air filter to be the problem, here is what to do next. First, you need to determine whether it is a reusable filter or not. If it is reusable, you can clean it and place it in the heater again. However, if it’s disposable, you’ll have to throw it away and buy a new one.

Cleaning reusable filters is not too complicated, though you have to remember to be gentle. You can either rinse it with a little water or use a small vacuum to suck up the dust. Each reusable filter has its own method for cleaning, so make sure you know which one applies to your filter.

Problem: Thermostat

In the event that problems persist despite checking the air filter, your next step would be checking the thermostat. It is possible that the thermostat is switched off or is not on the ‘heat’ setting. Additionally, it is possible that someone set the thermostat to a lower temperature and forgot to leave it higher.


For a faulty thermostat, you will need to pay close attention to its sound. To be specific, you have to pay attention to whether the heater makes a sound when you move the temperature from low to high. Normally, this should make a sound, but if it does not, you will know that the thermostat is responsible. You will need to enlist the aid of a technician to replace the faulty thermostat.

As a side note, where your thermostat is placed might also be the problem. If it is under direct sunlight or some other type of heating, it will register higher temperatures and shut off prematurely.

Problem: Insulation

The next possibility that you need to explore is insulation. To properly function and generate warmth, the heater needs proper insulation. Thus, when you purchase a heater, you need to be sure that your house is appropriately insulated. Otherwise, the heater will keep shutting off more often.


The fix for this is very simple (and free) for the most part. All you have to do is look around your house and check all the windows. Make sure that all of them are closed and there are no small openings anywhere. The idea is to ensure that no cold air is entering the house from anywhere.

Problem: Flame Sensor

Next, we’ll be discussing the flame sensor. The primary function of the flame sensor is to detect flames and switch off the gas valve if there aren’t any. This is an extremely important safety feature that prevents harmful gases from spreading throughout your home. Again, like the air filter, the flame sensor is subject to becoming worn out after continued use. In the case of the flame sensor, it can get corroded or covered in soot.

When it is compromised in any way, it cannot fulfil this function at all. It completely loses its ability to identify flames and as a result, it shuts off the gas valve. With the gas valve shut off, the heater can’t function.


This specific problem is of a technical nature, and there is nothing you can do to fix it by yourself. This is why the only real solution is to call in professional help so that they can take care of the situation. Essentially, they will be cleaning out the flame sensor so that nothing is blocking it anymore.

Problem: Space

Another possible problem could be that your heater is not suitable for the room you have placed it in. In this case, the problem is that the room is far too small. As a result, the room heats up very quickly when the heater is switched on and once the room reaches a certain temperature, the heater automatically switches off. Once it has fully cooled down, the heater switches back on. This is a process that continues many times until the heater completely breaks down.


Again, this type of problem cannot be resolved by yourself. The issue itself is such that there is no real solution. You will have to get rid of the heater currently in your possession and purchase a new one that is appropriate for your living space. You will need to call a contractor to carry out a heat load calculation to figure out whether your heater is oversized or not.

Problem: Vents

Another possibility is that the air vents on your heater are blocked in some way. This could mean that dust or debris has somehow entered them or that they are not opened all the way. Regardless of the situation, the vents are blocked. This causes problems with the heat exchanger. As mentioned earlier, when the heat exchanger does not receive enough air, it will become very hot and switch off the heater to protect it.


Thankfully, this problem has a very easy solution. You simply need to keep all your vents open. This will allow the heater to maintain a healthy air flow to the heat exchanger. With proper air cooling things down, your heater will no longer trouble you.

Some people are hesitant to keep all the vents open because doing so would generate too much heat. However, it is not necessary to open all of them; you just need to leave enough of the vents open so that the heat exchanger has access to the necessary amount of air.


As is the case with all home appliances, gas heaters are prone to breaking down. If your gas heater keeps switching off, you will need to do an inspection to determine what the problem is. After you have been able to determine what requires fixing, you can either solve it yourself or call professional help. The nature of these issues is such that some can be taken care of at home, but others absolutely require professional help. Either way, you will have a functional heater again, so fret not!

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