Water Heater Gas Valve Replacement Cost

On most gas tank water heaters, the gas control valve is the box on the front of the tank with the temperature dial. It controls gas to the pilot and burner and contains the thermostat. It is one of the more expensive repairs on a gas water heater.

Cost

Angi lists the valve part at $70 to $200 before labor and a gas thermostat valve assembly at about $80 for the part, about $200 with labor.

Signs of a failing gas valve

• The pilot lights and the thermocouple is good, but the burner will not come on.
• Water temperature does not match the dial setting.
• The pilot will not light at all even though gas is reaching the unit.

A plumber usually rules out the cheaper parts first: the pilot ($50 to $200) and the thermocouple ($100 to $325), both from HomeGuide. See thermocouple replacement cost.

Safety

Gas valve work involves the gas supply. If you smell gas, leave the house and call the gas utility before calling a plumber.

Repair or replace?

A new gas valve on a heater that is near the end of its life may not be worth it. HomeGuide suggests replacing a water heater that is over 10 years old or when a repair costs more than half the price of a new one. Angi lists gas tank replacement at $700 to $2,700. See gas water heater replacement cost.

What the gas valve does

The gas control valve on a tank water heater regulates gas to the burner and pilot and holds the thermostat that sets water temperature. Newer valves also include safety shutoffs that stop gas flow if the pilot goes out or the tank overheats.

Signs the valve has failed

• The pilot will not stay lit even after the thermocouple or flame sensor is replaced.
• The burner will not light, or will not shut off.
• Water temperature is inconsistent or the temperature dial no longer works.
• A diagnostic light on the valve shows a fault code.

What the repair involves

The technician turns off gas, drains the tank below the valve, disconnects the gas line, thermocouple or sensor wiring and burner tubes, unscrews the old valve from the tank, installs a matching replacement, and then leak-tests all connections before relighting.

What affects the price

Gas valves are one of the more expensive parts on a water heater, and the labor includes draining and refilling the tank. Brand-specific valves and power-vent units with electronic controls cost more.

More on repair or replace

If the tank is relatively young, replacing the valve is often worth it. On an older tank, the cost of a gas valve can be a meaningful share of a new heater's price, and many homeowners choose to replace the heater instead.

More on safety

Gas work should be done by a licensed professional. If you smell gas, leave the house and call your gas utility before calling a plumber.

In Texas

Gas water heaters are common in Texas garages and attics. After any gas valve replacement, a proper leak test and a check of the venting are essential, especially in tight attic spaces.

Gas valve vs. other causes

The gas control valve is one of the most expensive parts on a gas water heater, so it is worth confirming it has really failed. Before replacing it, a technician checks the gas supply, the pilot assembly, the thermocouple or thermopile, the vent and any safety sensors. Many valves are replaced unnecessarily when the actual problem was a cheaper part.

Signs that point to the valve itself include a pilot that lights but the main burner never fires even with a good thermocouple, water temperature that does not match the dial, a status light flashing an error code, or a gas smell at the valve.

What happens during replacement

The gas supply is shut off and the tank is drained, because the valve threads into the tank. The burner assembly, the gas line and the thermocouple or wiring are disconnected and the old valve is unscrewed. The new valve is installed with the correct thread sealant, the gas line is reconnected and every joint is leak-tested. The tank is refilled before the pilot is lit and the burner is tested.

The new valve must match the heater's make and model and the type of gas. Natural gas and propane use different valves and orifices.

Natural gas or propane

If your home uses propane, make sure that is stated when you ask for a quote. Propane valves are set for different pressures, and using the wrong valve is a serious safety risk. Switching a heater from one fuel to the other requires a conversion kit approved by the manufacturer, or a different heater altogether.

Is the heater worth the valve?

Because the job includes draining the tank and the valve itself is expensive, a gas valve replacement on an older heater often costs a significant share of a new heater. Ask for both prices. If the tank is old or shows rust, putting the money toward a replacement usually makes more sense.

Keeping the valve working

Valves fail less often when the heater is kept clean and properly vented. Keep the area around the heater free of dust and lint, and have the burner and venting checked when you flush the tank.

Warranty coverage

Gas valves are often covered by the heater's parts warranty for several years. Check the heater's label and registration before paying for the part. The manufacturer may supply the valve, leaving you to pay only labor. Keep the serial number handy when you call the manufacturer, since it shows the manufacture date and the warranty period that applies. Some home warranty plans also cover the valve, subject to a service fee.

Who should do this job

Gas valve replacement involves gas connections and leak testing, so it should be done by a licensed plumber or gas technician. Many areas require a licensed professional for any gas work, and a mistake can cause a leak or a fire.