Ignite your sleuthing side to figure out what’s wrong with your furnace
Imagine the temperature starts to drop, you turn on your thermostat to make things a little more cozy—and nothing happens. Your furnace ignitor could be to blame.
The furnace ignitor is a small component with a big job. It lights the burner, which sparks the combustion process and converts your fuel into heat. So if your furnace won’t turn on during a chilly night, you may have a problem with the ignitor. In this guide, we’ll explain how to check if your furnace ignitor is bad and what to do to fix it.
You can test your furnace ignitor using a multimeter if you have easy access to the ignitor. Shut off power to your furnace and wait for it to cool down entirely. Unplug the ignitor. Inspect the portion that heats to see if there are any cracks or if any physical damage is present. If there is no damage, set your multimeter to the lowest setting for ohms of resistance and place one multimeter probe on one terminal and the other on the opposite terminal. If you get a reading between 50 ohms and 400 ohms, your ignitor should function properly.
If you get a different reading, you may also experience one of the following problems. Check out what’s causing the furnace ignitor issues and how to solve the problem.
When a furnace doesn’t run at all, that could be a sign you have a bad ignitor that needs replacing. When the ignitor glows, it generates heat. But your furnace is built with a fail-safe option to shut it off in any critical situation.
If your house is cold, turn up the temperature on your thermostat and stand near the furnace. If you hear clicking but the furnace never kicks on and you don’t see the ignitor glowing through the louvers in your furnace, your ignitor is likely the issue. You’re going to have to call a furnace repair company near you to come out to replace the ignitor.
Unless your thermostat is set to cool, your ductwork shouldn’t be blowing cold air. If your thermostat is set to heat and you’re getting nothing but cool air, your ignitor may have failed to ignite the fuel to heat the circulating air.
You can confirm this issue by checking your air handler and your furnace. If the air handler is on, your thermostat is set to heat, but the furnace isn’t kicking on, your ignitor failing to light the fuel is probably to blame.
Does your furnace turn on and then off repeatedly? This is called short-cycling—a safety feature that happens when the furnace senses a potential safety problem.
When you have short cycles, the ignitor could be the culprit. Your furnace’s safety features could cause it to shut down if any of the internal components are found to be malfunctioning, including the ignitor. An error forces the system to shut off and wait at least 60 seconds before it starts again.
To save yourself from a significant furnace issue, shut off the power to the appliance to prevent ongoing cycling, and call a technician to inspect the problem as soon as you notice it has gone on and off a few times.
If your furnace keeps tripping the circuit breaker right after it starts blowing air, this could indicate a voltage issue related to your ignitor. If the ignitor is pulling too much electricity or creates sudden drops in voltage, you’ll see the breaker trip over and over until the problem is sorted out.
While a single breaker trip from the furnace ignitor can be a simple fix, repeatedly tripping the breaker can be dangerous for your furnace and for the electrical system in your home. Take this furnace issue seriously and be sure to leave the breaker set to “off” until the furnace problem is repaired.
This ignitor issue can be dangerous because you’re dealing with high-voltage electricity. If you’re in this situation, call a local furnace professional right away. If the issue is severe, they may red tag your furnace and require a replacement.
To kick-start the furnace, your ignitor creates a spark that makes a 'click' sound. But if you hear the click and no air seems to blow, you could have a dangerous ignitor problem you’ll need to have serviced by a local pro.
If you have an older furnace, shut it off right away and call in a professional. Newer models have safety features that will shut off the furnace for you if the gas doesn’t ignite. This prevents explosive gas from entering your home.
In either case, call a professional right away.
Don’t ignore the warning signs of a bad ignitor. Your first action should be to call a local furnace repair pro as soon as possible to get the issue diagnosed properly. This will help you reduce any further damage to the furnace. Since your furnace likely uses natural gas or oil and generates carbon monoxide during operation, a quick call to a professional can also keep you, your family, and your home safe from harm.
Install carbon monoxide alarms on every level of your home, in central locations, and outside bedrooms. Check all of your carbon monoxide detectors every month, and replace the batteries on a set schedule according to the manufacturer’s instructions.
An ignitor repair or replacement is often inexpensive—around $350—and can save you from a more significant furnace repair that will cost more. Most ignitors have a seven-year life span, so a replacement is often a more affordable option than a repair in the long run.
Don’t wait until winter is here to deal with heating issues. Schedule routine furnace checkups, and make sure you get one before the first freeze hits. Call a furnace maintenance professional near you to get yours looked at before you find yourself sleeping under four blankets to stay warm.
A furnace ignitor is the component that heats up to ignite the fuel coming into your furnace. A flame sensor—which is located on the opposite side of the furnace as the ignitor—detects the presence of a flame under your furnace to determine if and when it’s functioning properly. Your flame sensor can shut power to your ignitor to prevent the furnace from cycling on and off too quickly, and it can also close the gas valves to prevent the flow of gas if it isn’t ignited due to a faulty ignitor.
It’s possible to reset a furnace ignitor if you’re experiencing issues with your heat not coming on or your furnace cycling on and off too rapidly. Shut the power to your furnace and wait for it to cool entirely. Unplug the ignitor, and pull it out of your furnace. Leave it out for about five minutes, and test it using a multimeter to make sure it has continuity. After five minutes, plug the ignitor back in and turn the power to the furnace back on. If you still have an issue, call in a furnace repair technician.
There are many things that can cause your furnace ignitor to fail. It’s a complex component with a few safety features in place to prevent major issues. Some of the things that can cause a problem with your furnace ignitor include the following: there are loose electrical connections, there was a power surge during a storm, it’s the wrong size, there’s a carbon monoxide buildup, there’s a gas leak, or there’s cracking or damage in the heating portion.
