International Comfort Products sells gas furnaces under several brand names, including Heil. Some of the company's furnaces have a pilot light, and it's easy to tell if it's lit by visually inspecting it. Newer furnaces use a hot surface ignitor to light the burners. If you can't see a pilot light on your furnace, you may have one of these systems.
Older gas furnaces often have a standing pilot light that remains on all of the time. Locate the pilot light by finding the gas line that enters the furnace. This pipe is about the size of a garden hose and may be made of brass, copper or black steel. Inside the furnace, the gas line connects to a dull, silver-colored gas valve. Look for a small silver tube about one-fourth inch in diameter on the bottom of the valve. This tube is the fuel line to the pilot light. In addition to the tube, you should see a thin metal wire. The pilot light is located at the end of the wire and the tube.
Hot Surface Ignitor
A hot surface ignitor looks like a small heating element attached to a base. Two wires lead out of the bottom of the base. To find the hot surface ignitor on a Heil furnace, you'll need to remove the front panel. The hot surface ignitor will be near the front of the furnace. Look on the left hand side of the furnace, near the burners.
Hot surface ignitors use an electric heating element, similar to that used in an electric oven. When the thermostat calls for heat and the inducer fan is running, the furnace control supplies power to the ignitor, which causes it to heat up and glow orange. The heat from the ignitor then ignites the gas. When the flame sensor senses heat, the furnace control shuts off power to the ignitor. Information about the safety procedures in place for the hot surface ignitor can often be found inside the burner or blower access door. More information can be found inside your owner's manual.
If your standing pilot light won't stay lit, you may have a bad thermocouple or a bad gas valve. If the ignitor on a hot surface ignition system doesn't glow orange, you probably have a cracked ignitor. Turn the power to the furnace off before you replace an ignitor. To remove the ignitor, disconnect the wires that attach the ignitor to a plastic plug and socket. Remove the mounting screws and the ignitor should come out.
Hot surface ignitors are made with silicon carbide or silicon nitride. Silicon carbide ignitors aren't as durable as those made from silicon nitride and usually last only between three and five years. Silicon nitride ignitors can last up to twice as long. Eventually, all ignitors crack and need to be replaced.