A water heater works by heating cold water using heating elements at the bottom of the tank. The hot water is then transferred into parts of your home through pipes. The water heating process might result in pressure build-up within the water heater.
Pressure or steam build-up in a water heater is a potent force. The T&P relief valve is fitted to release excess pressure from your water heater. The T&P valve opens up when:
- The water pressure reaches 150 psi, and
- The temperature in the tank gets to 210 degrees.
But the T&P valve can break down, necessitating repair or replacement.
You must shut your heater and its cold water pipe before replacing the TPR valve. Wait for it to cool, in case it has hot water. Next, drain the tank to a lower level than your TPR valve. Remove your old valve. Carefully roll Teflon tape onto your new valve’s thread and screw it firmly to your heater. Switch on your cold water pipe and heater.
When Should You Replace Your T&P Valve
Typically, you should replace your TPR valve after 3 to 5 years. But this might happen sooner depending on the following:
- Water quality in your area. Hard water that is rich in minerals might block your TPR valve
- The structural integrity of the valve. Considering it is a mechanical component, it might experience failures such as leaks
- Your system’s inability to achieve its expected pressure
What You Need to Replace the TPR Valve
- Teflon tape/ PVC glue (pipe joint compound)
- New TPR valve
- Adjustable wrench
- Wire brush
Finding New T&P Valve
The T&P valve has a tag on its handle attachment. The information on this tag is what you’ll need to find the proper replacement. Buy a valve with a similar rating to your old one.
Hardware and home improvement stores stock the replacement valves you need. Check supply houses, too.
Consider getting universal valves that work with every water heater. Most of these are high-quality materials and will serve you longer.
TPR Valve Replacement Procedure
Once you secure the new valve, please fix it! To do this, proceed as follows:
Shut the Cold Water Supply
Cutting the supply of cold water into the tank prevents flooding your home’s basement. Shut off the cold water supply by:
- Turning the gate valve (it resembles a wheel) clockwise
- Pulling the ball valve handle to a 90 degrees angle
- In case you don’t have any of these valves or you do not know what to do, shut off your house’s main shut-off valve
Switch off the Heater
Cut power or gas supply to your water heater by:
- Flipping the circuit breaker (in case of an electric water heater) to “off.” The breaker has a “WH” or “Water Heater” label.
Draining the Tank
Drain your tank before commencing any replacements. This helps you avoid accidents and messes. However, do not drain completely to avoid damaging your heater’s heating element.
Most TPR valves are situated at the side of the tank, close to the top, or at the top of your heater.
Disconnecting the Discharge Line
With a drained tank, you can open the tank to release all the pressure. Next, disconnect the discharge line. Then, finally, cut it using a hacksaw unless you are tall enough to unscrew the valve.
Use a wrench on the discharge and another on the valve to apply opposing pressure. This approach prevents excess pressure on the valve and saves the tank from deforming at the top.
It also prevents the formation of the tank’s hole if the discharge is tightly screwed. Consider saving the discharge tubing if you cannot make a clean cut. You can buy a new discharge tub by putting everything together using coupling.
Unscrewing the T&P Valve
Since you have removed the discharge line, unscrew the valve using a pipe wrench. Tap the end of the pipe wrench with a hammer if the valve proves tough. Alternatively, place a pipe over the wrench handle and extend it.
The extension gives you more leverage. However, be careful and do not use too much force to avoid causing damage. Too much force on an empty tank leads to twisting.
Screwing the New Valve
Wrap the threaded end of your new valve with Teflon tape. Wrap the tape in the opposite direction of how you will screw in the valve. Screw it back into the tank.
Tighten it using a wrench while securing the position of the valve ends. They should be appropriate to reattach your discharge line.
Reattaching the Discharge Line
Apply Teflon tape to male threads before screwing it into your T&P valve. Then, you can couple it together after screwing it.
The attachment depends on the material of the line:
- PVC Lines: For PVC, you’ll have to buy a PVC coupling and the PVC glue to put everything back together. Apply the glue to the pipe’s end and the inner coupling, then push it onto the pipe.
- Copper Lines: Buy a “push fitting” coupling for copper discharge. The push fitting works great since you push it onto the pipe and make sure it clicks.
You don’t need to solder or use any special tools. Sand both ends of the pipe to cut burrs/build-up. This gives an excellent fit for the coupling.
Your discharge is likely to measure 3/4″ in diameter. Take a piece of the discharge to the store to confirm that the coupling fits.
Conduct Final Checks
Once you have reattached it, confirm that everything fits as it should. To do this:
- Confirm that the pilot lights and that your tank fires back up as expected.
- Refill the tank and confirm if the new valve leaks or operates appropriately. Attempt opening the T&P valve first by briefly flipping the little silver handle on top. Listen for the hissing sound when water flows.
- Give everything another quick check for leaks.
Do you have to drain the water heater to change the T&P valve?
Yes. You must drain water from your heater to a level slightly lower than your T&P valve.
How much does replacing a T&P valve on a water heater cost?
T&P relief valves are cheap. The total cost of buying and having a licensed plumber replace it ranges between $150 and $300. You can DIY for $20.
Replacing a water heater T&P relief valve takes work. But, with the steps above, anyone with mechanical skills can handle it. Alternatively, call in the experts to assist.
This video explains how to replace the water heater T&P relief valve easily.