furnace not working

Furnaces

What Does It Mean When the Furnace Pilot Light Is Out?

If your gas-fired furnace isn’t turning on and delivering heat, the reason could be a furnace pilot light out for some reason. While newer, gas-fired furnaces installed in homes light the main burner flame with an electronic igniter, many older furnaces still on the job utilize a pilot light. It’s simply a small, gas-fired flame that burns constantly and ignites the main furnace burner when the thermostat signals for heat. As a safety measure, a furnace pilot light out automatically shuts off gas flow to the main burner so the furnace will then not start up. 

Why Is the Furnace Pilot Light Out?

If the furnace isn't starting up as it should, it could result from two potential pilot light problems:

  • Thermocouple malfunction. The pilot thermocouple is a safety device that continuously senses heat from the pilot flame. If the flame goes out for any reason, the thermocouple immediately shuts off gas flow to the pilot light and the main gas burner. Sometimes, however, an aging thermocouple will begin to malfunction, shutting off gas even though the pilot light is lit and functioning normally. A qualified HVAC technician can test the thermocouple and replace it with a new unit if necessary.

  • Flame inefficiency. A normal pilot light flame should be bright blue. However, if the flame is yellow or orange, this is a sign that the gas is not burning efficiently and that the temperature of the flame is too low. Often, the thermocouple will sense the low-temperature flame and shut off the gas, including the pilot light. Flame-efficiency issues require diagnosis by an HVAC professional.

What to Do Now?

Most furnaces provide instructions to observe the pilot light and determine if it is lit. If it’s not lit, you can follow the basic procedure that's usually posted on the furnace to attempt to relight the pilot light. However, if the pilot will not relight — or if it goes out again soon after relighting it — discontinue further attempts and contact your HVAC contractor for a service call.

To resolve issues relating to a furnace pilot light out, contact the heating professionals at Air Assurance