How To Install a Water Heater Shut-off Valve

Many new-model water heaters come with an automatic shut-off valve located on the cold-water supply pipe. This device automatically cuts off the water supply to your heater if it detects a leak, potentially saving you from costly repairs and water waste.

Older or simpler models might not have this failsafe in place, but skilled DIYers can install one themselves. Below, we detail the installation process and other expert guidance. You can follow along with This Old House plumbing and heating expert Richard Trethewey in the video above.

How Water Heater Shut-Off Valves Work

All water heaters come with a manual valve to turn off the supply line by hand, but an automatic valve will shut on its own in case of flooding. These valves valve consist of two main parts: the valve itself and a float sensor. The valve is installed on the cold-water supply line leading to the water heater, and the float sensor is placed in a catch pan beneath the water heater. If a leak occurs and water accumulates in the pan, the float rises, automatically triggering the valve to close and shutting off the water supply.

Note that these automatic valves require electricity to work. The power cord is often quite long, and you will need to plug it into a standard wall outlet.

Benefits of Installing a Water Heater Shut-Off Valve

Here’s how installing an automatic water heater shut-off valve protects your home:

• Prevents extensive water damage in case of a leak
• Reduces the risk of mold and mildew growth from undetected leaks
• Lowers the potential for costly repairs and water waste
• Provides peace of mind for homeowners

Preparing for Installation

Before you begin the installation process, gather the necessary tools and materials and take all necessary safety precautions.

Tools and Materials Needed

To install a water heater shut-off valve, you’ll need the following tools.

You’ll also need these materials:

• Automatic shut-off valve kit
• Copper fittings (unions, repair couplings, threaded adapters)
• Copper tubing
• Catch pan
• Electric drainage pump
• Pipe dope
• Solder and flux
• Zip ties

Safety Precautions

Note that this project requires cutting into plumbing and opening gas lines. If you aren’t comfortable with this, hire a professional contractor to install the valve for you. If you decide to do the job on yourself, take these precautions:

• Turn off the power supply to electric water heaters or gas supply to gas water heaters
• Wear protective gear, including gloves and safety glasses
• Ensure proper ventilation when soldering
• Have a fire extinguisher nearby

Step-by-Step Installation Process

Installing a water heater shut-off valve involves disconnecting the unit to slide a catch pan underneath, and then inserting the automatic valve in the cold-water supply line. Follow this guide carefully to ensure a proper and safe installation.

Step 1: Draining the Water Heater

Before doing anything else, drain the water heater completely.

1. Turn off the water supply to the water heater.
2. Connect a garden hose to the drain valve at the bottom of the tank.
3. Open the drain valve and allow the tank to empty completely.

Step 2: Disconnecting the Water Heater

To install the new catch pan and shut-off valve, you need to disconnect specific components of the water heater.

1. For gas water heaters, shut off the gas supply and disconnect the gas line.
2. Use a tubing cutter to cut the cold water pipe leading to the heater.
3. Repeat the process for the hot water pipe.
4. Disconnect the flue from the top of the heater.

Step 3: Installing the Catch Pan

A catch pan catches water from leaks or failure events, and it’s where the float sensor will be installed. We recommend having an assistant help you with this step.

1. Carefully lift the water heater.
2. Slide the catch pan underneath the heater.
3. Gently lower the water heater back into place.

Step 4: Reconnecting the Water Heater

At this point, you’ll reconnect all of the elements except the cold-water supply line, where the automatic valve will go.

1. Reconnect the gas line, applying pipe dope to the threads for a secure seal.
2. Reattach the flue to the top of the heater, ensuring all screws are tightened for safety.
3. Reconnect the hot-water pipe using a repair coupling, soldering it in place.
4. Extend the overflow pipe with copper tubing so it reaches down into the new catch pan.

Step 5: Installing the Automatic Shut-Off Valve

With everything but the supply line reconnected, you can now install the automatic shut-off valve.

1. Solder a copper union onto a threaded adapter.
2. Thread the adapter onto the automatic shut-off valve.
3. Solder a second threaded adapter onto the cold-water pipe.
4. Cut away enough of the cold-water pipe to accommodate the shut-off valve.
5. Install the shut-off valve between the two adapters.

Step 6: Setting Up the Sensor

The sensor ensures the shut-off valve will switch on when water levels rise in the catch pan.

1. Plug the sensor into the valve.
2. Place the float sensor in the catch pan.
3. Use zip ties to secure the overflow pipe and sensor wires.

Step 7: Testing the New Valve

After installation, test the shut-off valve to ensure it’s functioning correctly.

1. Turn the water supply back on.
2. For gas water heaters, turn the gas back on and relight the pilot light.
3. Manually raise the float sensor in the catch pan to simulate a leak.
4. Listen for the valve to close, indicating that it’s working correctly.
5. Check that the water supply to the heater is now cut off.

Maintenance and Troubleshooting

Regular maintenance and prompt troubleshooting can help ensure your water heater shut-off valve continues to function effectively. Here are some tips:

• Inspect the catch pan regularly for signs of water accumulation
• Test the shut-off valve annually by manually raising the float sensor
• Check for any signs of corrosion or damage to the valve and sensor

Common Issues and Solutions

If you encounter issues when you go to test the new valve or perform later maintenance, try these fixes:

• If the valve fails to close during testing, check the sensor connection and replace the shut off valve if necessary.
• If water accumulates in the catch pan without triggering the valve, clean or replace the float sensor.
• For persistent issues, consult a professional plumber for a thorough inspection and potential replacement.

Additional Considerations

If you’re still worried about water damage from leaks and flooding, these additional devices can work with an automatic shut-off valve to improve the integrity of your water heater.

Installing an Expansion Tank

An expansion tank can help manage pressure changes and prevent damage to your water heater and plumbing system. It absorbs excess water pressure that can build up in a closed plumbing system, thereby reducing stress on the shut-off valve. Choose an appropriate expansion tank compatible with your water heater and install it on the cold-water supply line, following the manufacturer’s instructions.

Adding a Leak Detection System

If your home has smart devices, you can install a comprehensive system to alert you in real time if a leak is detected. Research these leak detection systems and choose one that’s compatible with both your plumbing setup and smart devices. Install it according to the manufacturer’s instructions and test it to ensure it sends the proper notifications.

Our Conclusion

Installing an automatic water heater shut-off valve is a wise investment in home safety and protection. For those uncomfortable with DIY projects or dealing with complex or old plumbing, hiring a professional plumber will ensure the installation is done correctly and safely. Once it’s installed, remember to regularly maintain and test the shut-off valve and associated components to check that they’re working correctly.