How to replace a furnace ignitor



A furnace is one of the most important home appliances you can own. It is the cornerstone of most HVAC systems and is essential for controlling your home’s temperature and comfort level. Since furnaces are so important, a breakdown can be catastrophic. 

In these situations, it helps to know how to make minor repairs to your furnace. The only problem is that repairs can be tricky. You should have some knowledge regarding gas furnace functions and components before trying to make repairs yourself. 

This article will take you through some common problems with furnaces and the steps for replacing a gas furnace ignitor safely and quickly.


Can you DIY a furnace ignitor replacement?

In short, yes, you can DIY a hot-surface ignitor replacement. It shouldn't be too difficult if you have experience fixing things around the house. However, if you typically feel clueless about troubleshooting household appliances, this may not be the right job for you. In this case, it might be better to call your home warranty company and ask it to send a repairman. 

Furnaces are not simple machines. They have a complex system of electronic modules, exhausts, blower fans, gas valves and complicated wiring. Modern furnaces work on electricity and gas and can cause injury or shock if you are not careful. So, it’s important to do the following: 

  • Turn off the furnace and pull its plug from the wall socket.
  • Do not touch anything with bare hands, especially the ignitor. Wear gloves. 
  • You are the best judge of whether you are up to the task. Call an expert if it's too daunting. 


How to replace a furnace ignitor in 4 steps

Before we jump into how to replace the furnace ignitor, let's try to understand what an ignitor is. Until about 2010, natural gas or propane gas furnaces had pilot lights that burned continuously. Sometimes they would blow out, and you’d have to make your way to the furnace to reignite them. Some furnaces had spark ignitors that would spark to create ignition. When you set the thermostat to a warm temperature, the gas would let out so it could ignite when it came into contact with this perpetually burning pilot light or spark. 

Furnaces also had a metal rod called the flame sensor, which would sense heat or ignition and shut off the ignitor once it created enough heat. The furnace would then carry the heat through the house. Modern furnaces don’t use this pilot light or spark ignition system. Instead, they use hot-surface ignitors that use electricity to heat up. 

A hot-surface ignitor is a device in contemporary furnaces that ignites the gas to produce heat for the house. Once the furnace control board supplies power to the ignitor, it starts to heat up. The gas turns on when the ignitor turns bright orange with heat. The gas ignites when it touches the hot ignitor. The ignitor itself is made of ceramic and silicon carbide. These materials are extremely fragile and break often. This delicate part of the furnace needs replacement now and then. 

Consider investing in the newer silicon nitride ignitors if you don’t like replacing your furnace ignitor regularly. They are much more durable and outlast the silicon carbide variety by two to seven times. 

It’s important to always keep an extra ignitor or two in the house in case the one in the furnace stops working. You can find ignitors online and through local wholesalers. You may also find this replacement part in stock at a hardware store. You’ll need a screwdriver to remove the mounting screws that attach the ignitor to the furnace and a pair of gloves to replace the ignitor. 

Step 1. Turn the furnace off and disconnect the ignitor

Turn off the furnace completely by unplugging it from the wall before opening the access door. You will see a few electrical wires wrapped in a plastic plug attached to a socket. Pull out the plug and disconnect these wires to ensure safety while working on the appliance.

Step 2. Remove the ignitor mounting screws

Next, use a screwdriver to undo the screws that hold the ignitor to the furnace. Carefully examine the ignitor to see if it has discoloration or a crack on it that might be causing it to malfunction. If the ignitor looks fine, the problem lies somewhere else. 

If the ignitor isn’t the issue, call a professional to look at your furnace. They can figure out what’s wrong and initiate furnace repair work. However, if the ignitor is broken, you’ll need to replace it. Remove the old ignitor from its spot in the furnace. 

Jot down the furnace make and model number while looking inside. These will come in handy next time you buy an ignitor. 

Step 3. Install a replacement ignitor

Next, carefully get the new ignitor out. Be very cautious with it because ignitors are sensitive and fragile. We recommend using gloves while handling an ignitor. Grease, moisture, or oil from your skin can cause it to malfunction later or damage it permanently. 

Insert the new ignitor into its place in the furnace and screw the nails in gently. (The ignitor will likely break if you tighten the screws too much.) Reconnect the wire plug into the socket and attach the access door to the furnace. Plug in the furnace once everything is securely put back in place. 

Step 4. Turn on the furnace

Set the temperature on the thermostat and wait. Listen to the sounds from the furnace to ensure that the ignitor is firing things up inside. Once you set the temperature, the ignitor will start to heat up. 

As it reaches optimal heat, the gas valve or safety valve will open to allow gas to travel to the ignitor. Contact between the ignitor and the gas will create ignition. Heat will slowly flow through the furnace to the house after ignition. 

If the temperature rises after a few minutes, you have successfully replaced your ignitor! But remember, ​it is equally important to invest in regular furnace maintenance and have professionals look at it every once in a while.


How much does a furnace ignitor replacement cost?

Overall, replacing the ignitor yourself is the cheapest option because it saves significant labor costs. If your furnace is under warranty, you’ll have to pay an average cost of around $150 to have someone replace your ignitor (primarily the cost of two hours of labor). If your unit is not under warranty, the expense to have an HVAC company or HVAC technician come in and replace the ignitor can be up to $255. 

In contrast, the average DIY replacement cost is between $20 and $45. Most hot-surface ignitors cost between $15 and $75 for the replacement part (which is universal). However, if your furnace requires an OEM (original equipment manufacturer) part, the repair cost might be slightly higher. Since purchasing an ignitor is your only expenditure if you replace it yourself, the overall cost is much lower. 


A Cinch warranty covers heating systems (including ductwork)

Investing in a reliable home warranty service company is a good way to extend the life span of your home systems. Regular servicing and timely repairs can go a long way in getting the most out of your appliances. Cinch Home Services offers a great Built-in Systems plan for homeowners. Our plan covers most home systems, including air conditioning, HVAC, plumbing, smoke detectors, water heaters and more. 

This means that any time your furnace or air conditioner acts up with a covered issue, all you have to do is file a claim with Cinch. We’ll set you up with an HVAC system technician to come to your home as soon as possible. If the product is beyond repair, Cinch will cover the replacement cost for a new furnace. 

Most importantly, our plans provide access to Cinch’s network of experienced and certified technicians, and our 180-day workmanship guarantee ensures your home’s smooth functioning is in safe hands.

Get your instant quote with Cinch today!


Confused about how to replace your furnace ignitor? Read on to learn the safest and cheapest way to fix your heating.