Reply #5: The valve that controls the flow of gas is electric, I believe

[krispos42]

Pilot light is basically a tiny, lit gas leak. When the thermostat clicks the heat on, an electrically-operated valve pops open, letting the full flow of gas into the furnace. The gas hits the pilot light and bursts into flame.

If the electric valve isn't opening, then either the thermostat is not telling it to open, the electric valve's power supply is turned off, or the electric valve is broken somehow.

If your thermostat is turned off, or to "Cool" or "A/C", that would do it. If the circuit breaker to the furnace is turned off or tripped, that also would do it as well.

The valve should "click" when the thermostat is turned up.



A non-electrical possiblity is that the valve that controls the main flow of gas is turned off. The gas valve usually has a position where you can keep the pilot light lit but turn off the full supply of gas. Something like "Off/Pilot/On" positions you can turn the knob to. If somebody moved the knob to "Pilot", that would keep the fully flow of gas from happeneing.



More modern furnaces don't use a pilot light. They use an igniter like the kind on your gas grill. When the thermostat turns the heat on, the full gas flow turns on, then the igniter lights the gas.