Q: I have an older gas furnace in my home upstairs that works very well, but I haven’t had it maintained it in a few years. I think the pilot light looks weak, but there’s no setting for a higher flame. How can I improve the pilot light flame? – Nancy in Buffalo, N.Y.
A: There is a way to control the height of the pilot light flame. Next to the “Pilot” indicator on the furnace’s control switch, there is a small screw located near the pilot light-thermocouple assembly. I’ll typically shine a small flashlight and use a magnifying glass to read the imprinted type on the control housing to make sure that’s the right screw.
With the pilot light burning, use a Phillips-head screwdriver to carefully turn the screw one way and then the other, watching the pilot light to see if it gets stronger or weaker. The flame should be angling toward a nearby object that looks like a small vertical pipe: This is called the thermocouple, an important safety device. If the pilot light goes out, the thermocouple detects it and shuts the valve supplying gas to the pilot.
The pilot flame should touch the thermocouple at a specific level. If the flame is blue and weak, and barely reaches the thermocouple, it needs to be stronger. If it extends well above the thermocouple, it’s too strong. If the flame covers the top of the thermocouple and burns steadily with a yellow tip, that’s just about right.
What if the pilot light won’t stay lighted? If the assembly looks OK, turn off the gas supply at the nearest valve and try heating the thermocouple using a match for about 30 seconds to a minute. Then relight the pilot.
If that doesn’t work, replace the thermocouple by carefully unscrewing it from the control housing using an open-ended wrench, being careful not to ding or bend the supply pipe or the pilot-light assembly. Install a new thermocouple by screwing it in, heating it up a bit, and then lighting the pilot.
Keep in mind that this task can be a little frustrating, because you’re almost always working in a cramped, hard-to-access spot. Be patient and take frequent breaks if necessary, rather than compromise safety or damage the unit.
HOME TIP: Make sure you know exactly where the main shutoffs for your home’s gas, water and electrical supply are located, and that you know how to turn them off in an emergency.
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