Imagine waking up on a cold winter morning, donning your bathrobe and heading downstairs to the kitchen to make your morning coffee. You find it unusually cold, so you instinctively walk up to the thermostat, bump the temperature up a few notches and wait for the kitchen to warm up. There’s just one problem — nothing happens. The furnace isn’t kicking on and there’s no air is coming out of your registers.

What could be wrong? There could be a numerous reasons why your furnace won’t turn on, but today we’ll focus on one: a faulty or failed furnace ignitor — also known as a hot surface ignitor.

This is a small device used in furnaces to ignite the gas and start the heating process. Think of it as a toaster of sorts: when electricity is sent to the ignitor an exposed, resistant metal (think a toaster coil) becomes hot enough to ignite the gas. Usually the ignitor’s material is composed of silicon carbide or nitride carbide.

Quality furnace ignitors usually have a lifespan of 4-7 years, but they can prematurely fail for a few reasons:

• Improper handling of the ignitor: certain surfaces of the ignitor need to be free of oil and debris, and if contamination occurs, ignitor lifespan can be greatly reduced.
• The ignitor is not properly matched to the furnace: sometimes a less than honest HVAC company will not have the specific part on hand and simply install a replacement part that is not properly matched to the furnace. It may work for a little while, but it will end up failing prematurely.
• High home voltage: Anything over 125 volts may cause premature failure by putting too much strain on the furnace ignitor.

If you suspect a furnace ignitor failure, call a trusted HVAC professional to properly diagnose and repair the problem. To get the most out of your furnace and its vital internal parts, change your filters on a regular basis and consider a maintenance contract.