Furnace Not Igniting? - How to Check and Replace Ignitor (Step By Step Guide)
So your furnace is not heating and you think that your ignitors have gone bad. A simple visit from a technician can cost a minimum of $200 in case of ignitors.
I have been in the HVAC repair business for about 6 years now and I know that this is not a major problem and can be solved by yourself at home.
So In this article, I’ll tell you how you can troubleshoot and test your ignitor at home. And how you can replace them. Remember that ignitors are not that expensive they usually cost between $30- $60. So you don’t have to stress over it and also the installation of a new one is pretty easy.
Different Types of Ignitors - How to Check and Replace Ignitor
First, let’s discuss different types of ignitors:
Standing Pilot Ignitors - Different Types of Ignitors
Only very old home furnaces have standing pilot ignitors, but these ingitors are more commonly found in factories or large industrial settings. These types of ignitors have to manually light the flame and there is a little flame that stays on all the time. They work by heating up a small area of the fuel until it starts to flame, which then spreads to the rest of the fuel. This helps to ensure that your furnace is burning evenly and efficiently, reducing the amount of wasted energy and saving you money.
And if you think you have that but you're not sure an easy way to check is to just look on your gas valve. A standing pilot ignitor typically has a long, slender body with a round head. It is often white or silver in color, and has several small, round ports on its surface. Usually it'll have a knob on top of it that'll have an on, off, and a pilot position.
Direct Spark Ignitor - Different Types of Ignitors
Direct spark ignitors are the most common type of furnace ignitor. They work by creating an electric current that ignite the fuel in the furnace. With a direct spark igniter, the gas valve opens and sends gas through the manifold to all the burners. The electric spark then ignites the gas right away.
This type of ignitor is simple and easy to use, which is why it's used in many types of furnaces. These ignitors are generally pretty loud. If that's what you have, you'll probably hear it when the furnace is trying to start; these ignitors tend to make a pretty loud racket. A direct spark ignitor on a furnace looks like a small, metal object with a pointed end and a round, metal base.
Intermittent Pilot Ignitors - Different Types of Ignitors
Intermittent pilot lighters are kind of like the standing pilot ignitors, but they are intermittent. It only turns on when there's a call for heat when the thermostat is sending those signals. The purpose of an intermittent pilot ignitor is to create a consistent and controlled flame, which helps to prevent thermal shock and increases efficiency.
Whenever there's a call for heat the pilot valve opens on the gas valve and lets a little bit of gas through and then a spark will ignite that pilot flame and once a flame sensor or a thermocouple senses that the flame is there. Then the main gas valve opens up and lets the flame through. These units are typically used in small to medium-sized furnaces, and they are not as common as direct heat furnaces. Indirect heat furnaces produce less pollution than direct heat furnaces, and they are also more energy efficient.
The pilot ignitor is a small, self-contained unit that uses an electric current to ignite the fuel in the furnace. There will be a little pilot hood and typically the gas valve will have a little silver tube, the pilot tube, coming out of it.
Hot Surface Ignitor - Different Types of Ignitors
Hot surface ignitors use a little glow stick that glows up to about 1200 degrees; this is what ignites the gas. They are also known as camshaft ignitors, and can come in different shapes, sizes, and types depending on the type of furnace they are used in. Most furnaces have this one ignitor installed.
A hot surface ignitor on a furnace can look like a long, thin metal tube with a ceramic or plastic tip at one end. They may also have a red ball at the end instead.
How to Troubleshoot Your Furnace Ignitor - How to Check and Replace Ignitor
Step 1: Ensure the Furnace is at a Moderate Temperature - How to Troubleshoot Your Furnace Ignitor
The furnace must be at room temperature in order to test the circuit, check the ignitor, and look for visible damage.
Step 2: Deactivate the Furnace and Remove the Furnace Control Panel - How to Troubleshoot Your Furnace Ignitor
Using the thermostat, turn off the furnace. Afterwards, locate the ignitor by unscrewing and removing the service panel on the furnace's side. Near the gas port, it is typically fixed on a V-shaped bracket.
Step 3: Turn the Circuit Breaker Off - How to Troubleshoot Your Furnace Ignitor
Turn off the furnace's circuit breaker, which is often either on the appliance or in the main breaker box of the house. By doing so, it will ensure that you are not injured in the case that the broken ignitor is dangerous.
Step 4: Check For Damage That is Visible - How to Troubleshoot Your Furnace Ignitor
If the ignitor is twisted, chipped, cracked, damaged, etc., it needs to be replaced.
Step 5: Now Turn Your Circut Breaker and Furnace Switch Back On - How to Troubleshoot Your Furnace Ignitor
Now the second thing you need to do is turn on the the circut breaker and furnace switch again. Maybe the answer to your ignitor issues is that the whole system needed a hard reboot.
After this, you’ll see your inducer motor getting started. Then you’ll hear your gas valve open up (usually a click sound). If the gas started to flow but nothing is happening (not igniting) then your ignitor may be bad.
Step 6: Check Your Ignitor Switch - How to Troubleshoot Your Furnace Ignitor
Now if your ignitor is not working then you can try to check your ignitor switch. Sometimes that switch becomes loose and that’s what causing the ignitor to not work. Tighten the switch and check if your ignitor starts functioning again or not. If it doesn’t glow, spark, or start a small flame then your ignitor may be bad and require replacing.
Step 7: Take Ignitor Wires Out of Their Socket - How to Troubleshoot Your Furnace Ignitor
Use pliers to pry the wires' plugs out of their sockets within the furnace only if the ignitor appeared to be unharmed upon previous inspection.
Step 8: Check Your Ignitor with a Multimeter - How to Troubleshoot Your Furnace Ignitor
With a multimeter, you can check the ignitor’s voltage and resistance. Both the inspection are necessary so do test for both things.
Checking the Voltage to the Ignitor
If the ignitor is getting voltage but it's not igniting that means the igniter is bad. But if it's not getting voltage that means something else is wrong or maybe the control board is bad and it's not sending power to it.
So to check the ignitor’s voltage Just remove the ignitor switch and place the probes of a multimeter on the tips of the ignitor plug. Then set the multimeter to the lowest resistance test setting. A healthy flow of power should be around 120 +-Volts. If the multimeter reads infinity or remains at zero then there is an issue with your furnace that is bigger than the ignitor. Your ignitor switch is not getting current from the control board and you need to check it.
How to Check the Ignitor with the Multimeter
Now once you checked the voltage if it’s getting proper voltage. Then you need to check your ignitor’s switch with a multimeter.
Now set your multimeter to ohms and put the leads into the ignitor’s switch. The ideal ohms rating for a good ignitor is between 40-90.
So if your ignitor’s rating falls between that limit then your ignitor is good. And if it’s jumping to 100 or 250 then it’s close to its end cycle. One thing to note is that you should always check your ignitor’s resistance at room temperature. Because if you take a working furnace ignitor reading (resistance) then the results may vary.
How to Replace Your Furnace Ignitor - How to Check and Replace Ignitor
Step 1: Turn Your Furnace Power OFF - How to Replace Your Furnace Ignitor
The first thing that you should do when working on any electrical appliance is ensure that it is turned off. Before working on your furnace, you should turn its power switch off and also turn it off at your circut breaker. There are a few reasons why it is important to turn off a furnace before using it. The first is that if the furnace isn't turned off, it could cause potentially dangerous sparks. These sparks could ignite materials in the furnace and cause a fire.
Another reason to turn off a furnace before using it is that if the furnace isn't turned off, you might not be able to get out in time if there is an emergency. If there's a fire inside the furnace, you won't be able to escape quickly enough because of the heat and smoke. Additionally, electrical shocks can be hazardous.
You don’t want to operate the furnace while the power is running—it could have potentially fatal conseqences.
Step 2: Remove Your Switch and Unscrew Your Ignitor - How to Replace Your Furnace Ignitor
Now you need to unplug the ignitor’s switch and unscrew the ignitor.
Step 3: Replace the Ignitor and Put it Back - How to Replace Your Furnace Ignitor
Now you need to replace the ignitor with a new one. To do that just unscrew the ignitor’s bracket and remove the old one and replace it with the new one. Now put your ignitor back on the furnace and plug the switch back and check if it’s working properly or not.
Conclusion - How to Check and Replace Ignitor
It is entirely possible for individuals to fix their own furnace. Luckily, replacing or working on an ignitor is usually an easy job. As long as you have the correct equipment and take the proper safety precautions, you should able to work on your own furnace just fine.
However, if you are not comfortable fixing your furnace, consider hiring someone else to do the job. Sometimes, and especially for complex issues, it may be safer and more efficent for a licensed professional to take a look at your heating system.
