PLEASE REFER TO YOUR MANUFACTURER'S INSTALLATION MANUAL FOR INFORMATION REGARDING YOUR SPECIFIC MODEL. IF YOU ARE ATTEMPTING TO SERVICE YOUR HEATER, PLEASE DO SO WITH CAUTION, TANKLESS PROSAZ, LLC. AND THE OTHER ORGANIZATIONS MENTIONED BELOW ARE NOT RESPONSIBLE FOR ASSOCIATED LIABILITIES. THIS INFORMATION IS FOR EDUCATIONAL PURPOSES ONLY.

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How does a gas control valve work?

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What is a Gas Valve? 

The gas valve is the temperature and gas control found on most tank-type water heaters designed for use with Natural Gas or LP (Propane). It is based on the temperature setting and is responsible for maintaining a small-lit pilot flame and opening and closing the incoming Gas to the water heater's main burner. 

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Some other common names in place of "gas valve" include Gas control, Gas control valve (aka GCV), Gas control thermostat, and Thermostat. Although some manufacturers or plumbing professionals may refer to it simply as a gas valve as a "thermostat" or "t-stat," please note that this is different from the Thermostat (s) found on an electric water heater. 

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Where is the Gas Valve Located?

The gas valve is at the bottom of the heater on residential water heaters, just above the burner chamber. It can typically be seen outside of the water heater. Although some commercial standard atmospheric-type water heaters may have gas valves at the bottom of the unit, most commercial water heaters have gas valves at the top. 

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Anatomy of a Gas Valve:

A water heater gas control valve may appear relatively simple based on its general description above. However, gas control valves are complex, containing their control boards and solenoids, which enable them to oversee a gas water heater's operation and maintain temperature settings. 

 

Here is a basic overview of a gas control valve for residential water heaters; we will not discuss the interior electronic components in detail. 

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Temperature Control adjustment Knob

This knob allows the user to set the desired temperature for their desired hot water needs. 

The U.S. Consumer Product Safety Commission and the Energy Conservation Act recommend setting all residential water heaters to 120 degrees Fahrenheit to prevent scalding and consume energy.

 

Comfort Setting

Most professionals recommend water heater comfort settings of 125 degrees Fahrenheit in the summer and 130 degrees Fahrenheit in the winter.

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Legionnaires Disease 

Always set your water heater above 125 degrees Fahrenheit to prevent bacterial growth contributing to Legionnaires disease associated with water heaters.

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Gas Control Valve Status Lights

Some gas control valves have a Status Light that does not typically cover temperature adjustments.

This light will flash a steady blink, Indicating the water heater's status as normal or flashing in sequence, indicating a fault with the operation or in need of service. Further information may be found on an attached label adjacent to the gas control valve or in the operation manual that should have accompanied your water heater. 

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Gas Pilot Igniter

Usually found at the top of a gas control valve or on the face, this is how you light the pilot flame for the lower chamber burner assembly. It works much the same way as a backyard BBQ. Clicking the button sends an electric impulse spark to ignite the pilot light inside the chamber next to the main burner. 

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What should the light on a gas valve do?

If your water heater has a gas control valve has an indicator status light, the light should generally blink continually white, typically once every four (4) seconds, indicating that the water heater is usually working; alternatively, the light may also alternate from bright to dim, indicating that the unit is heating water. If the light is off, there is no lit pilot flame to the unit; if there is any other flash sequence or the light is red, there is likely an issue with your unit. 

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For details about your specific unit, please look at your installation manual, which typically includes a diagnostic and troubleshooting chart; some gas valve models may also have a label with flash codes and explanations directly on their face plates. 

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Please refer to your unit's gas valve and installation manual for specifics. Flash codes differ by gas valve model; some errors may be generic.

 

How do I know if my water heater's gas valve needs to be replaced?

The most common indications that your gas valve needs to be replaced include Gas valve-related flash codes, no hot water, or inconsistent hot water (although many other issues could cause this). It is probably the gas valve if you have changed the pilot assembly and still do not have a consistent flame.

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How much does a replacement gas valve cost?

This depends on three major factors: the age of the unit, its size, and the availability of the gas valve. A residential gas valve typically costs between $175 and $450.00 (or more) each.

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Before contacting a service provider, check and see if your water heater is still covered under warranty; during your phone call to the manufacturer, they may be able to confirm the diagnosis of a faulty gas valve and send you a replacement part. If your unit is still under warranty, they typically send the part for free, with the option to add expedited delivery for a fee. The average gas valve replacement requires a technician to be on-site for typically 1-hour. 

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Call Tankless Pros Az

These guys are professionally trained and certified to diagnose and solve water heater issues. They are technicians who diagnose faulty water heaters, check for gas leaks, and ensure your unit functions properly.

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Common Causes of Water Heater Gas Valve Failures 

It may be more common than you think! Residential water heater gas valve replacement is one of our most common diagnosis and repair services.

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Some common causes of gas valve replacement include: 

• Incorrect Gas Valve: Installing a Natural Gas Control Valve on an LP (propane) or vice versa.

• Not regulating the hot water temperature correctly. 

• Broken or damaged gas control valves.

• Not allowing a pilot light to remain lit, although in some cases, this is due to a faulty thermo-coupling or thermopile sensor.

• Older valves: Sometimes, an old valve will begin to stick in a closed, open, or halfway position and not function correctly.

 

Common Misdiagnosis:

Forgetting to Pay the Gas Bill. Sometimes, customers think they have a faulty pilot assembly or gas valve when their pilot assembly will not light or will not remain lit. In some cases, this may be due to a lack of available gas supply (low or no pressure); if you have forgotten to pay your natural gas bill or have not had a visit from your LP (propane) gas supplier to replenish your tank, your water heater will no longer produce hot water. 

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Can I replace a Gas Valve on my own?

Someone with prior plumbing and/or HVAC knowledge may be able to do so independently. 

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Are Gas Valves interchangeable?

No. Unlike other parts (namely, electric water heaters), gas valves are NOT interchangeable. Gas valves are usually specific to the model and production date range. This means that two water heaters with the same model number may have two different gas valves and two different pilot assemblies. Gas valves vary in size and type depending on whether the water heater is a Standard Atmospheric or Power Vent, Natural Gas or LP, the water heater's size, ignition type, and more. Each factor plays a role in the kind of gas valve they need.