Does Your Furnace Have A Broken Safety Switch?

Posted on: 11 July 2023


Furnaces are complex machines. As such, it is not uncommon for small parts of pieces within a furnace to fail and require replacement. One such part that sometimes fails is called the safety switch. Keep reading to learn all about furnace safety switches, the signs that yours has broken, and what an HVAC contractor can do about this problem. 

What is a safety switch?

A safety switch really has two roles. First, it detects that there is a fire burning in your furnace. When it detects that fire, it turns the blower unit on to ensure air passes through the furnace and collects heat from the fire. The second job of the safety switch is to detect when the furnace is getting hotter than it should. If it does detect an elevated temperature, it turns the furnace off. It thereby helps prevent fires and overheating.

What are the signs your safety switch has broken?

Most furnaces are designed so that if the safety switch breaks, the furnace does not turn on. This way, your furnace won't overheat or start your home on fire. So, the most obvious sign of a broken safety switch is that your heater simply won't turn on. You might hear the furnace click as though it is going to turn on, but then air never comes out of the ducts. 

In older furnaces, a broken safety switch sometimes causes the furnace to run indefinitely. You may have air coming from the ducts at all times, whether or not the furnace is actually heating.

What should you do about a broken safety switch?

Since you are lacking an important component of fire protection, it's not wise to run a furnace with a suspected broken safety switch. So, turn the heat off and find somewhere else to stay until an HVAC contractor can look over your furnace.

If your HVAC contractor does confirm that your safety switch is broken, they can usually replace it on the spot. This is a small part that only costs a few dollars, and replacing it is not very labor-intensive, either. If your furnace is newer, the repair will probably be covered under warranty.

Furnaces include safety switches for a reason — to keep you safe. If you think yours may have failed or is failing, contact an HVAC repair company in your area. They can take a look, give you a quote, and make the needed repairs. 

For more information on furnace repair, contact a professional near you.