Hot Surface Igniters are Resistance Heaters
2021-04-26
How They Work
Hot surface igniters are a resistance element made of silicon carbide or silicon nitride. Anywhere from 80 to 240 volts are applied to the wires attached to the igniter. A ceramic base insulates the wire connection to the carbide element which looks like the letter M on most applications. Spirals are another shape I see. Most nitride igniters are formed in the shape of a 1.5-inch flat stick or a 2-inch long cylinder.
When the voltage is applied to the wires, the element starts to glow because of the resistance the carbide creates from one wire to the next. When it glows long enough, gas is poured over it, and the flame ignites.
Hot Surface Igniters are Resistance Heaters
As mentioned earlier, hot surface ignitors, or HSI’s, are resistance heaters. The element itself glows orange when the voltage is applied. How hot that element gets depends on the voltage being applied to it. A 120-volt HSI will glow at around 2500 degrees Fahrenheit. Most gas fuels will ignite around 1100 degrees, so 2500 degrees is a little excessive. A 240-volt igniter burns even hotter. Several control boards these days are made to support an 80-volt igniter. This way the carbide breaks down slower, adding life to the system.
Hot Surface Igniters are Better Than a Pilot Light
Before hot surface ignitors and spark ignition was around, we had gas pilot lights that would stay lit burning a 1 to 2-inch flame year-round whether the heat was on or not. When the heat was turned on, the gas valve would flow more gas over the pilot to ignite the burner assembly that carried the flame.
As mentioned earlier, hot surface ignitors, or HSI’s, are resistance heaters. The element itself glows orange when the voltage is applied. How hot that element gets depends on the voltage being applied to it. A 120-volt HSI will glow at around 2500 degrees Fahrenheit. Most gas fuels will ignite around 1100 degrees, so 2500 degrees is a little excessive. A 240-volt igniter burns even hotter. Several control boards these days are made to support an 80-volt igniter. This way the carbide breaks down slower, adding life to the system.
Hot Surface Igniters are Better Than a Pilot Light
Before hot surface ignitors and spark ignition was around, we had gas pilot lights that would stay lit burning a 1 to 2-inch flame year-round whether the heat was on or not. When the heat was turned on, the gas valve would flow more gas over the pilot to ignite the burner assembly that carried the flame.
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