Once upon a time, more or less every residential gas furnace was equipped with a pilot light to accomplish the task of ignition. Now, however, more and more furnaces utilize a so-called hot surface igniter instead. This component utilizes electrical energy to start off the process of combustion. In this article you will learn more about how a hot surface igniter accomplishes this task.
Sequence Of Events
The first thing that happens when your furnace receives a call for heat is that the induced draft motor starts up. This ensure that, once combustion has started, the exhaust by-products will be safely vented out of your home. A sensor then reports that the motor has successfully started, thus allowing the process to continue.
This is where the hot surface igniter comes into play. The furnace’s control board allows electrical energy to flow to the igniter, which can soon be seen glowing red hot. To ensure that it has reached a sufficient temperature, a certain amount of time is allowed to pass before the gas valve opens up. Once the gas has begun flowing into the burners, it is quickly ignited by the hot surface. As soon as combustion has been initiated, electricity ceases to flow to the hot surface igniter.
For optimum safety, a hot surface ignition system utilizes what is known as a flame sensor. The flame sensor is able to detect the heat caused by combustion. When it does, it sends the signal to stop powering the hot surface igniter. If, on the other hand, a certain period of time elapses in which the flame sensor cannot detect a flame, it will automatically shut off the gas valve. This keeps raw gas from entering your home.
To learn more about the various components that make up your gas furnace, contact the experts at ABA Heating and Cooling.