Your water heater has a pressure release valve to regulate pressure build-up. Without it, your water pressure could reach dangerous levels, causing damage to the heater.
Knowing how to replace a water heater pressure release valve is a valuable skill if you suspect yours is faulty and needs replacing. We explain the best water heater valve replacement techniques and run through the costs.
How Does a Water Heater Pressure Valve Work?
Your water heater creates internal pressure when the water heats inside the tank. Steam is powerful, and the tank could explode if left unchecked. The pressure relief valve (TRP) works by opening a tap to let water out of the system to reduce the pressure.
The temperature trigger in the valve operates via a thermostatic element. When the temperature goes above 210 degrees Fahrenheit, it expands, pushing a piston onto a disk. This opens the channels to drain hot water to reduce the pressure levels inside the tank.
As the load diminishes, the system stabilizes, and the pressure valve closes. If the switch is faulty or leaking, you’ll need to perform a water heater pressure valve replacement.
The same is also true if your valve keeps opening to depressurize the water heater. It indicates that the valve is faulty and needs fixing or replacing.
Look at the diagram above to get an idea of the internal components of a water heater relief valve.
Water Heater Pressure Relief Valve Check
Checking a pressure valve is easy. Lift the lever on the top of the valve and wait while water flows out of the tap.
If your hot water heater sits in a basement with a floor drain, attach a length of hose and flush the water directly down the drain. When you lower the lever, it snaps shut, cutting off the water.
You should perform a relief valve check at least once a year as part of your annual maintenance schedule.
Word Of Caution
Checking an old valve could create a leak because you are disturbing an overflow that has been sealed for years.If you have a leak,you will need a bucket to catch the water because it will be extremely hot.
How to Replace a Water Heater Pressure Release Valve
Knowing how to replace a water heater relief valve could save your boiler from serious damage when the pressure builds. In rare instances, it could save your life!
What You’ll Need
- Pipe wrench.
- New relief valve.
- Teflon tape.
- Safety gloves.
Removing the Old Valve
Before attempting a new valve installation, you will need to pop off the old one cleanly and without damaging the attached pipe.
Check the pipe to see if it is hot. It may be a good idea to wait for the water to cool first. If not, at least wear safety gloves, like these KAYGO Polyurethane Safety Gloves.
- Shut the water off and turn the temperature down on the water heater.
- Open the nearest hot water faucet to allow water to drain and remove the vacuum that could be present in your pipes.
- Attach the hose section to the bottom of the tap on your drain valve. If you have a floor drain, lay the hose over the drain. Hold a bucket under the tap to catch the water if you don’t have a hose.
- Lift the lever and drain the water to a level just below the height of the valve. You don’t need to drain it all the way down.
- Grab the pipe wrench and remove the old copper pipe attached to the valve. Do this as cleanly as possible because you will need to use it again later.
- Remove the valve and take a trip to the hardware store to match the new valve. Alternatively, shop online for a replacement, like this Camco model.
Installing the New Valve
With the old valve removed, it’s time to install the new one. Stick with it because you are on the home straight.
- Use Teflon tape to secure the threads of the new valve. Ensure that you wrap the tape in the same direction as the threads, or it will unravel when you screw the two components together.
- Use the pipe wrench, and tighten the valve, so the Teflon tape grips and the tap faces the right way.
- Use Teflon tape to attach the copper drop tube and twist it in place.
- Turn off the hot water faucet and turn the water back on. Set the temperature back to its original position and wait for the tank to heat.
- Check for leaks around the new valve, and when the water reaches temperature, test the lever to see if the water drains as it should. If you spot dripping water, you must perform the whole procedure again.
How to Find a Replacement Pressure Valve
How many times have you bought a replacement pressure valve? Once, twice, or not at all? We suspect for most people, the answer is never.
So, how do you ensure you get the best valve? Here are some hints and tips to help you shop for a pressure valve.
When you remove the old valve, take it to the hardware store and get the closest possible match. You may even get a branded valve that matches your water heater manufacturer.
Alternatively, you could contact the manufacturer to get official spares for the best fit.
Wait While the Water Cools
Relief valve problems are easier to spot on a boiler when the water is hot. However, it doesn’t mean you should attempt to fix it while the water is scalding. Wait for the water to cool before draining the tank.
Match the Pressure Rating
Most hot water heaters have a maximum pressure rating of 150 MAWP (Maximum Allowable Working Pressure). Your new temperature and pressure relief valve (T&P) should equal the pressure rating on the heater.
However, it is possible for some water heaters to have a MAWP of 160. You may also see these numbers represented as PSI (Pounds Per Square Inch), but the principle remains the same no matter how you measure the pressure.
How Do I Fix a Leaking Pressure Relief Valve?
In many ways, fixing a leaking pressure release valve is more challenging than replacing it. They are inexpensive to buy and come as a complete unit. The only time you should attempt to work with your old valve is if the source of the problem is easy to spot.
The most common fault is scaling, when the disk and piston become caked in mineral deposits. This is especially problematic in hard water areas.
You can fix the issue by attaching a hose and draining the tap to remove the limescale. You could also try flushing the water tank through at least once a year to keep mineral deposits to a minimum.
You may have to replace the Teflon tape wound around the threads because the valve has been knocked, and a small leak has started.
Keep In Mind
Unless the problem is obvious, we would recommend replacing the entire valve.
Water Heater Pressure Relief Valve Replacement Costs
How much does a new relief valve cost? Well, if you’re replacing it yourself, between $15 and $30. If you call the professionals, it could cost as much as $100 to $200.
Knowing how to replace a water heater relief valve could save you over $170 on professional installation fees. You can also chalk it up as another life lesson learned if it fails again.
The best way to avoid the issue in the first place is to keep on top of maintenance. That way, you can spot problems quickly and deal with them before they worsen.