How to Replace a Water Heater Gas Valve

Find out how to remove and replace a water heater gas valve in a few easy steps. How to change the temperature on the gas control valve, safely.

This article will cover the most popular and used gas valves: White Rodgers, Robert Shaw and Honeywell, all used in atmospheric, direct and power-vent water heaters, which utilize the pilot light. These three models can be found on most of the heating units from AO Smith, Rheem, State, American, Bradford White, GE, Kenmore and other popular manufacturers.

A water heater gas valve is one of the most important elements, and as part of the manifold/burner assembly is located in the lower section of the gas heater, with the several elements attached: manifold tube, pilot tube, piezo igniter, and thermocouple. This is one of the most important parts of the gas water heaters because your safety and correct operation of the unit directly depend on its proper work.

How to remove the gas control valve

  • Turn the gas control valve on the heater clockwise to the OFF position (counter-clockwise for the Honeywell model). If you own the water heater with the White-Rodgers gas valve, the knob must be depressed before switching to the OFF position.

  • Turn the gas supply OFF to the unit by using the manual shut-off valve, located beside the heater.

  • Turn the water supply OFF.

  • Drain the water heater.

  • Disconnect and remove the piezo igniter, manifold tube, pilot tube, thermal switches and thermocouple, but be careful about the direction of the thread. The termocouple has the right-hand thread, LP uses left-hand thread on the manifold tube, for example.

  • Use the correctly sized threaded pipe and put it into the inlet to unscrew and remove the valve. Avoid using the pipe wrench to grip the valve. It is very important not to put any objects inside the inlet or outlet, to avoid any damaging.

How to replace the gas control valve

  • Use the Teflon tape, or approved pipe compound when installing the gas valve onto the water heater and when reconnecting the gas tube.

  • Use the threaded pipe to screw the valve back, but do not overtighten as it may damage the valve and cause the gas leaking.

  • Reattach the piezo igniter, manifold tube, pilot tube, thermal switches and the thermocouple and pay attention to the thread direction.

  • Be sure that there isn't anything left in the combustion chamber that might affect the proper combustion, also dirt and debris that can enter the gas valve and cause it to malfunction. Ensure that there are no cracks, loose connection, etc.

  • Refill the water tank heater, open the hot water tap for several minutes to purge the outstanding air.

  • Test the gas valve for gas leaks. You can use a foamy soap/water mixture on the sponge and apply on all gas connections. If you see any bubbles, there is a leak and the corrections should be made.

  • Use the lighting instructions found on the heater or the user guide to start the water heating.

Adjusting the temperature

Gas control valve is equipped with the temperature dial with different settings, which allows change of the temperature from its minimum to its maximum (cold and hot), and has the most economical and safe setting, which is around 120 F.

Gas water heaters are factory set on 120-125 F as the optimum temperature that is safe for kids. The recommended temperature from the manufacturers is between 120 and 140 F, making it good for showers and dishes. Clockwise direction increases the temperature, while counter-clockwise, lowers.

Whatever temperature you select, the water heater will turn the unit OFF at this temperature all the time, unless you change it.

One important note: if the water heater gas valve is broken do not attempt to repair it, replace it. It is even better if you call the technician. According to the manufacturers, this element is nonrepairable.


Replacing thermocouple

TPR valve

Gas burner

Dip tube

Pilot light

Anode rod

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