Furnace Fuel Valve Troubleshooting And Repair Guide

A gas furnace needs a properly working fuel valve system in order to heat the air in your home. Issues with the fuel valve can range from delivery to ignition, so it will be necessary to troubleshoot the problem.

Gas Valve Operation

The gas valve is the part that delivers the fuel to your furnace burner so that the home heating process can begin. When the thermostat signals that it is time for the furnace to fire up, the valve opens and supplies gas to the burner. The igniter activates at the same time, combusting the gas and beginning the heating process.

There is also a flame sensor, which detects whether ignition happened properly. Older furnaces may not have an igniter, but instead may have a pilot light that remains lit at all times. Instead of a flame sensor, a thermocouple is installed that will shut down the gas if the pilot light goes out. 

Signs of Trouble

The most obvious sign of trouble is that there is no heat from the furnace. You may hear it click on when the igniter tries to light the fuel, but then no hot air comes from the vents. Some furnaces may continue to blow cool air as the blower will still run even with no gas delivery, while some models may shut down completely if there is no fuel coming from the valve.

On pilot light models, the most obvious sign of a gas valve issue is that the pilot light is constantly going out and having to be re-lit. A pilot light may go out occasionally, but it shouldn't be a common occurrence. 

Repair Options

The best way to repair the issue depends on the problem. If the furnace is an older model with pilot light problems, often the best repair is to simply replace the furnace with a newer and more energy efficient model. If you prefer to keep the furnace, then the fuel valve may need to be cleaned, replaced, or re-calibrated.

Any furnace can suffer from a clogged or damaged fuel valve, which will require either cleaning or replacement. A malfunctioning igniter or thermocouple can also prevent ignition of the fuel or cause the pilot light to go out. In this case, the easiest repair is to simply replace the broken component and then have the rest of the fuel system thoroughly cleaned. 

Contact a furnace repair contractor if you suspect issues with your furnace gas valve.

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