All forced hot air furnaces feature a furnace blower that ensures proper air circulation. Typical furnaces consist of the burner, the furnace blower and the plenum. When using hot air furnaces, you need gas or oil in order to turn on the burner. The air heats up in the plenum and runs through the burner, allowing the hot air to be blown away from the plenum to the room you want to heat up. The furnace blower ensures the proper function of the furnace. In the case that something goes wrong and the furnace doesn’t work properly, there will be a complete waste of money and energy. If you see that your furnace doesn’t shut off, that could lead you to consider many possible problems. For instance, the limit switch might be in bad condition, or the blower control set might have a problem. Another common problem is the wrong adjustment of the limit control. Here is a list of what you need to do in the case the burner doesn’t shut off.
Figure Out what the Problem is
The first thing you have to do is figure out where and what the problem is; in order to do so you have to understand how the furnace works. You cannot determine the real cause of the problem without knowing how the furnace is lit and how it operates. If the furnace won’t turn off and blows colder air towards the end of the heating process, you should check the temperature control. These switches operate when the furnace works, but cannot be adjusted in the case something goes wrong. You need to replace the switch right away if you think it’s not working. If, on the other hand, the burner doesn’t shut off, but warm air still comes out, there is obviously a thermostat problem.
Turn the Furnace Off
If you think that there is some problem with the thermostat, you should lower it a little in order to be able to turn the furnace off. If lowering the thermostat doesn’t work either, you should switch the thermostat off completely. Once you turn the thermostat off, the burner will also shut off–followed by the furnace blower. You need to do this in order to determine the thermostat works properly. If the blower and burner stop only when you manually turn the thermostat off, you will need to replace the thermostat.
Ask for Professional Help
Unless you are good with electrical devices and their components, it is most likely that you will not be able to locate the problem on your own. Even if you do so, you might have a hard time fixing it. Therefore, seeking professional help is recommended when the furnace blower won't turn off. Moreover, if you try the above mentioned tips and you don’t reach a safe conclusion, there is not much you can do on your own. For instance, if you turn off the thermostat but the burner and blower do not turn off, then the problem might be in the fuse box, the supply of gas or oil, or a wiring problem. An expert can find the solution within a few minutes.