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Why won’t the pilot light on my furnace stay on?

Posted on February 26, 2014
by Appleby Systems

A pilot light plays an integral role in the beginning phase of the gas ignition process. A dependable pilot ensures the heating cycle will function safely while maintaining a warm and comfortable indoor environment.

A malfunctioning pilot light is a condition that should usually be addressed by a licensed HVAC contractor. In any instance where the smell of gas is present, the furnace should be immediately shut down until the problem is diagnosed and repaired.

Common Pilot Light Problems

The pilot light is a small, controlled flame that is used to ignite the gas that flows into your furnace. Older systems require manual operation while new furnaces are equipped with electronic ignition systems. A pilot that will not stay lit is usually caused by one of the following conditions:

* Clogged Orifice: The orifice at the end of a pilot light is a magnet for the accumulation of dirt, grime and soot. When the tip is clogged, the flow of gas is blocked, and the pilot light may not stay lit. Minor clogs can be removed with a stiff bristle brush. Stubborn grime that is embedded in the flame channel can be removed by soaking the tip in a degreasing solution.

Faulty Ignition Switch* Faulty Ignition Switch: Modern furnaces use electronic ignition systems to create a spark that lights the pilot. Ignition problems can be identified by turning off the power at the electrical box and resetting the breaker a few minutes later. After the furnace is turned back on, check to see if the ignition sparks and the burn cycle begins. If there is no activity at the igniter, an HVAC service company should be contacted.

* Adjusting the Flame: Some furnaces are equipped with a manual flame adjuster. When the size of the pilot flame is too small, the burners will not engage and the pilot may be extinguished. Incremental adjustments to a controlling screw bolt will increase the size of the flame, which will often correct the problem. For safety, it is important to keep the dimensions of the pilot flame within the manufacturer’s design parameters.

* Gas Leakage: If there is a leak in the gas line connected to the furnace, there may be an insufficient amount of available reservoir gas to sustain the pilot flame. A gas pipe leak is a potentially serious safety issue that should be corrected immediately by the local gas utility or a licensed plumbing contractor.

* Thermocouple Problems: A properly functioning thermocouple uses heat sensors to determine if the pilot light is on or off. When the pilot is off, the thermocouple ensures that the flow of gas is shut down. When a thermocouple fails, it may not recognize that the pilot is on, and gas will not flow to the burners. In this situation, once the gas reservoir is empty, the pilot light will be extinguished. In some cases, repositioning the thermocouple so it is directly in the pilot’s heat-flow path may correct the problem.

Dependable Furnace Operation

Dependable Furnace OperationA gas furnace represents a significant investment in warm indoor comfort. Pilot light issues may be indicative of a more serious operational problem, especially in furnaces that are more than 15 years old. Homeowner’s with an aging or obsolete furnace are encouraged to explore the many benefits provided by a new, Energy Star certified central heating appliance.

If you’re experiencing furnace issues, or you think it’s time to update your HVAC equipment, contact us today.

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