Furnaces come in all shapes and sizes, some new and some old. Gas and electric (also known as air handlers) are common types of furnaces we see and repair at Bend Heating. Although, you’ll only find a gas furnace with a hot surface ignitor. These occasionally go out, which isn’t a major cause for concern. However, if your hot surface ignitor won’t reignite or keeps going out, you might have a bigger problem. Here are a few basics about hot surface ignitors, how to fix them, and what steps to take next if it’s malfunctioning. 

What Is A Furnace Hot Surface Ignitor?

A hot surface ignitor is what lights your flame with natural gas. Essentially, it’s a ceramic resistor that glows red hot (at over 2,000 degrees) and when natural gas passes through, it ignites. The best example is an electric stovetop. Some common reasons your hot surface ignitor wouldn’t work include too much gas pressure, a control board malfunction, contamination, and more. 

Check out our deep dive blog on furnace lockout for more potential causes of your furnace not working.

How To Diagnose Your Furnace Issue in Four Steps

If you have a hot surface ignitor and are comfortable with fix it yourself, here are a few basic steps to try. If you do not feel comfortable, it is important to keep yourself safe and contact an HVAC technician for help with your furnace. Note that these instructions are for a traditional gas furnace. 

Step 1: Turn Your Furnace Off

Turn your furnace off, stopping the gas flow to your furnace. If you don’t know how to do this, reference the instructions on your furnace. Confirm that the power is in the OFF position before proceeding. 

Step 2: Wait!

Wait 5 minutes to let any gas fumes from your furnace dissipate. This is an important safety step before you try to reignite the furnace. 

Step 3: Look For Cracks Or Breaks

First, locate your hot surface ignitor. It’s always located in the burner assembly on the far right or far left and is usually bracketed near the flame stream. Once you locate it, check for breaks or cracks. This is the number one cause of furnace malfunctions our service technicians regularly see in Bend, Oregon.

Alternatively, your hot surface ignitor may not work because there’s no resistance. If you want to take it a step further, you can unplug the ignitor and make sure you have resistance moving through it. Try unplugging the Molex and putting your electric leads towards the ignitor. If your OMS is below 100, then your hot surface ignitor is good, but if above 100 then it’s bad. If you do have resistance, then something else is wrong with your unit. 

Step 4: Call A Service Technician For Repairs Or To Order A New Part

If this workaround doesn’t fix your furnace, we recommend calling an HVAC technician to investigate the issue. Various issues could cause your hot surface ignitor to go out, especially if you have an older gas furnace. These problems might include airflow or a draft near your furnace, thermocouple malfunction, gas supply issues, or the age of your heating system. 

Find NATE-Certified Technicians In Bend, Oregon

Bend Heating’s reputation in the Central Oregon area is unparalleled. Our HVAC technicians are NATE-certified, which means we stay up on the latest evolving HVAC technologies, to ensure every repair is done safely and with expertise. To get the answers you need and turn the heat back on, hire an expert to diagnose, estimate, and repair your gas or electric furnace.