Most modern furnaces have a component inside it called a hot surface ignitor which lights the furnace every time the thermostat tells the furnace to come on. A hot surface furnace ignitor operates on 110volts or 115 volts and it glows red hot for about 5 to 30 seconds depending on the type of furnace.

Raw gas is release simultaneously and as soon as it hit the hot surface it lights, that’s what lights the furnace and then it starts to produces heat. Every time your furnace comes on it goes through that energizing cycle. So over the course of the winter that energizing turning on and off of the hot surface ignitor may occur thousands of time.

Now a hot surface ignitor is pretty much the only component in a furnace that we know has to be replaced periodically because it burns out. Just like a light bulb, which has a very limited life span.

The material used to make the hot surface ignitor is made out of a material call silicon carbide and under normal conditions the igniter should last for 3-5 years. However, it will eventually crack and need to be replaced, quicker if the oils from your skin get on the element by improper handling. Now there is a new type of material called silicon nitride which last almost twice as long. So if you’re purchasing a new furnace ignitor to replace the one that fail on you, you might want to pick up the new type made out of the silicon nitride.

Replacing the furnace ignitor

First thing that you would want to do is, pull out the furnace ignitor from your piece of equipment. Which is pretty much easy to do, it’s usually hold in place by one screw. There are two different method used to find your replacement. The first is to look at the model number for the one you have and then search for that exact number online to get a replacement and the second method is to simple visually inspect the one you have and then look at the ignitors online and find one that looks most similar. The characters to look for are the basics, where it will connect to, the element itself and then the wiring harness where it connects to the furnace.

If you don’t find one exactly like the one you have online, keep in mind that the most important characteristics is just to get it to fit in place. That’s because they all operate on 110 or 115 volts. So as long as you can get one that can physically fit in place and electrically connect you will be fine. There are also universal models, some comes with multiple wiring harness adapters so that it will connect to the adapter that you have in your furnace, or you could even cut off the adapter wires and replace it with the adapter from your old furnace ignitor. It doesn’t matter which wire connects to which because it 110 or 115 volt AC.

Something to keep in mind when you do replace the ignitor and you’re handling it, is to be very careful because the tip is fragile. It’s made out of a glass like substance which can break quite easily. So use precaution when handling it.

Because hot surface ignitor is knew to go out periodically every 3 to 5 years for standard, or if you have a nitride model which last twice as long. You’re always going to have one on hand so that, on the coldest day of the year if that furnace ignitor should fail you can make that replacement. It will only take a few minutes and save yourself an expensive service call.

Furnace Ignitor