The days of relying on a pilot light to ignite your furnace's burners are long gone. Modern furnaces use a variety of more reliable and efficient ignition sources, such as hot surface igniters. While pilot lights were perfectly acceptable options for igniting a burner, they required substantial maintenance and wasted a surprisingly large amount of natural gas.
While hot surface igniters are much more reliable and require very little maintenance, they sometimes fail. However, many people may also condemn this easy-to-replace part without confirming that the problem doesn't lie elsewhere. Before assuming your igniter is to blame for a furnace that won't light, it's important to understand how a professional technician would diagnose this problem.
Hot Surface Igniters Explained
The hot surface igniter (HSI) is an incredibly straightforward way to ignite the gas in your furnace. This device receives mains voltage, which causes the electrode at the end to become incredibly hot. If you watch your furnace ignite with the chamber door open, you'll see the igniter glowing bright red moments before the flame appears.
Ultimately, there's no magic happening here. Natural gas and oxygen will ignite in the presence of sufficient, which the hot surface igniter supplies. When this fuel mixture comes into contact with the hot electrode, your burner will ignite. The design of a typical furnace allows the ignition to spread rapidly from one burner to the next once the first burner lights.
Common Causes of Ignition Failure
Hot surface igniters can fail for numerous reasons. These devices experience extremely high heat so they will wear down over time. However, you shouldn't expect a hot surface igniter to "naturally" fail unless your furnace is fairly old. Instead, more common causes of failure include build-up and contamination on the surface or electrical wiring issues.
It's fairly easy to spot a faulty hot surface igniter since it won't glow red when the furnace begins its ignition sequence, and your burners won't light. However, many things must happen before your igniter receives the voltage necessary to start the burners. If anything prevents the startup sequence from proceeding on schedule, your igniter will never get a chance to light.
Troubleshooting Ignition Faults
A professional technician won't immediately condemn your HSI simply because it doesn't light. Instead, they'll need to confirm that the furnace's startup sequence is proceeding correctly up to the point of ignition. It's then necessary to confirm proper voltage at the igniter since a wiring problem or a control board issue can potentially prevent it from receiving power.
While igniters are cheap and relatively easy to replace, blindly replacing one that doesn't light may not solve the problem. Even for a seemingly simple ignition issue, it's necessary to rely on a professional HVAC technician to perform the diagnostic steps required to confirm the problem and avoid replacing good parts unnecessarily.
To learn more, contact a heating repair service.