It's important to have regular furnace maintenance so your furnace is safe and efficient to operate. The combustion area in particular needs to be cleaned and serviced to get rid of soot and carbon since the parts may malfunction if they get too dirty. Here's a look at some things a furnace maintenance technician may do to service the combustion area.
Observe A Heat Cycle
The technician can often tell by listening to your furnace start up if the parts are working okay. When the furnace is triggered to kick on, the inducer motor starts first and creates a humming sound. A few seconds later, the gas valve opens. This should make a clicking sound. If the hot surface igniter is working properly, it should be hot by the time the gas valve opens.
When the ignitor gets hot, the gas immediately ignites the burners and makes an ignition noise. If the furnace maintenance technician doesn't hear the burners ignite but hears a gas escaping sound instead, it means the hot surface igniter needs to be serviced.
Clean The Burners And Combustion Area
The burners and combustion area should be cleaned around once a year or more. This might include scrubbing carbon off and vacuuming it out. The hot surface ignitor is in the back of the burners, but your furnace maintenance technician probably won't bother it unless it isn't working properly. That's because the ignitor is fragile, and it could be broken by pulling it out to inspect it.
Replace The Hot Surface Ignitor
Many parts in your gas furnace can be cleaned to keep them in operation. An ignitor might need to be replaced instead. Sometimes the problem is a crack in the ignitor or the ceramic holder. Cracks can't be repaired, so the technician has to put in a new ignitor. Other times, the ignitor might be coated with black carbon. Cleaning the ignitor may not be possible since that could damage it, so it will be replaced.
The furnace maintenance technician can test the ignitor with a multimeter to see if it's broken. They can also test the power supply to verify the problem is in the ignitor and not the cables leading up to it. Replacing a hot surface ignitor may be an easy job or a difficult one depending on the way the furnace is designed.
Typically, the technician unscrews the old ignitor and slides in a new one. The difficult part is reaching the part if it's positioned at an odd angle and hard to reach. Once the combustion area is cleaned and the ignitor is verified to be working properly, the furnace maintenance technician can proceed to clean the blower motor and service other parts.
A few years ago, I could tell that we were having serious furnace problems. In addition to dealing with a house that was constantly too cold or too warm, we were also plagued by a noisy, smelly furnace that seemed to have trouble on a daily basis. Unfortunately, I didn't know enough about furnaces at the time to spot the problems quickly. One day, the entire system died, and it was beyond repair. After having that experience, I learned a lot about HVAC systems, so that I could troubleshoot future systems. This website is all about teaching you what you need to know so that you don't end up in the same situation.