The Hot Surface Igniter is found on most modern furnaces. These igniters are used to light the gas flames when the thermostat calls for heat. Electricity passes through the carbide and makes it glow red hot. The igniter can heat to upwards of 2,200 degrees. Operating under normal conditions, a hot surface igniter will remain efficient for up to 5 years. After that, it may lose efficiency, not get as hot, and be more likely to crack or go out. Just like in a light bulb, the filament does not last forever and the igniter will fail. Pozitive Heating and Cooling can replace this item when needed.