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Pilot Light Switch

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A pilot light switch is designed to prevent premature failure of the spark igniter or glow coil in the event a lengthy gas interruption occurs while the thermostat is calling for heat. The device operates using exactly the same principle as a gas-pressure switch used in the manifold of the gas-fired furnace or boiler. The switch is installed in the pilot gas line between the pilot and its regulator. Examples of setups that include a pilot light switch include a Carrier/Bryant Glow Coil or a General Electric gas furnace with an original gas valve setup.

Types Of Pilot Light Switches

As burners have evolved, the components have evolved as well. Such is the case with pilot light switches. For an older model, an example is a Carrier 2H pilot without a glow coil and using SPDT (single pole, double throw) switch action that can be used with 11-volt glow coil systems. The main orifice is a .021, though there is a second--sized at .031 that's to be used solely as an escapement orifice. This should be used only on installations in which an escapement tube is connected between the gas valve and this orifice. A more recent model would be a thermocouple pilot light switch, such as those made by Johnson Controls. Here, a manual reset SPDT switch is used with a nominal 30 MV thermocouple. While the former looks like a large igniter or glow bar, the latter device looks like a simple, small electrical box, about 2 inches by 4 inches.

Replacing A Pilot Light Switch

As with any electrical repair, the most important step is to shut down the electricity to the furnace. The pilot light switch may be mounted by a couple of screws. Simply unscrew, then unattach the electrical wires from the metal connectors. Remove and replace with a new switch. A very simple replacement.

Who Makes Pilot Light Switches?

Among the companies making pilot light switches are:

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