Why Your Furnace Is Overheating (And How to Fix It)

Is your furnace overheating? Furnaces are designed to generate heat. They consume either gas or electricity to generate heat. Air will then pass over the heating elements or coils while simultaneously absorbing this heat. Furnaces, however, can produce too much heat. When overheating occurs, it can take a toll on your furnace’s components while potentially creating a safety hazard.

Faulty Limit Switch

A faulty limit switch may cause your furnace to overheat. All furnaces have a limit switch. It’s an electric sensor that’s designed to turn on and off a furnace in conjunction with the thermostat.

If you set the thermostat for a higher temperature, the limit switch will turn on your furnace until this temperature has been achieved. A faulty limit switch means that your furnace may continue to run and potentially overheat. You’ll need to replace the limit switch if it’s faulty.

Faulty Gas Regulators

In the case of gas furnaces, a faulty gas regulatory may lead to overheating. Gas furnaces have a gas regulatory that, as the name suggests, regulates how much gas they release within the combustion chamber. If the gas regulatory is faulty, your furnace may release an insufficient amount of gas, or it may release an excessive amount of gas. In the latter scenario, overheating may occur.

Gas regulators are simple devices that can typically be replaced without investing in a new furnace. Nonetheless, you’ll need to replace the gas regulatory if it’s faulty to protect your furnace from overheating.

Dirty Air Filter

Something as simple as a dirty air filter can cause your furnace to overheat. Many homeowners assume that air filters only affect their air conditioning system and not their furnace. Air filters, though, are responsible for cleaning all the air that travels through your home’s ductwork. Whether you’re using your air conditioning system or furnace – or even just the fan – the air must travel through this mesh filter.

If the air filter is dirty, it may cause your furnace to overheat. A dirty air filter will restrict airflow through your home’s ductwork. This means less air will work its way back to your furnace. And with less air reaching your furnace, heat will accumulate at the furnace. Fortunately, this is a quick fix; you just need to remove the dirty air filter and replace it with a new air filter of the same size.