We gush over technological advances to our shiny Sub-Zeros and glitzy Viking ranges, but when was the last time you heard someone rave about the modern features found in their new water heater. Water heaters are often taken for granted and don’t possess the “Bling Factor” of other home appliances but their attributes are attractive in their own way.
They have a wide range of fancy new built-in features, but star billing goes to the safety feature that protects our homes and families 24/7; the Temperature Pressure Relief valve or TPR Valve.
This blog covers TPR valves in detail including what TPR valves are, what they do, how to inspect them and step by step instructions on how to replace them.
What is a TPR or Temperature Pressure Relief Valve?
The TPR valve is a special safety valve and it’s responsible for making sure your hot temperature-pressure relief valve water tank stays within its designed temperature and pressure limits.
It’s located on top or on the side near the top of your water heater. The valve has a lever that can be lifted up or down and a discharge pipe that runs from the valve straight down to the bottom of your water heater.
What Does a TPR Valve Do?
Water heaters can start to shake just like your clothes steam and moisture produced is greater than normal. The steam increases the pressure inside your water heater causing it to become unstable. Water heaters can start to shake just like your clothes washer does when it’s overloaded or unbalanced. This is where the TPR Valve comes into play. When something goes wrong, the valve automatically opens to release excess pressure through a discharge line.
If your water heater doesn’t have a TPR valve or if the TPR valve ceases to function properly, your water heater can literally blow up and put the safety of your family and home at risk.
This little device is vital to the overall safety of your water heater, your home and your family and it needs to be checked, inspected, maintained and/or replaced to prevent overheating and excessive pressurization.
How to Inspect a TPR Valve
Inspecting your TPR valve before replacing it could save you time, money and a big mess.
- It is possible the water heater pressure relief valve is not seating correctly. To find out you will need to open it up a few times to blow off some of the water. The water will wash out any sediment or obstructions.
- Before you do this you are going to want to cool the water down. Shut off the power to the hot water tank. For an electric hot water tank, you can shut off the breaker. On a gas hot water tank, you will want to turn the gas valve to ‘Pilot’ or ‘Off’. Run hot water into a sink or tub. When the water is lukewarm and not dangerous you can stop.
- Get a pail to catch the water from the valve. You want to hold the pail under the outlet when you release the pressure. The valve does not turn; instead, you lift it up to open it. Open the valve for a few seconds and then close it. Do it a few times.
- Turn the power or gas back on and let the water heat up. Check to see if the temperature-pressure relief valve holds. If it’s holding, great and if it’s not, you’ll need to replace the valve.
- To replace TPR valve, first purchase a new valve. Different water heaters have different TPR valve pressure and temperature ratings. Standard ratings are 150 psi and 210 degrees for temperature. There should be a little plate on the valve that gives you the correct figures but takes your old TPR valve with you to make sure the figures match. TPR valves are readily available at most hardware and Big Box Home Improvement stores and range in cost from about $18-$40.
In order to replace your TPR valve, you’ll have to partially drain your water heating tank. If it’s an electric water heater, turn the breaker off and turn the knob to pilot if it’s gas. The water coming directly out of your water heater will be extremely hot, so run an indoor hot water faucet until the water feels lukewarm. - Shut off the cold water inlet valve and hookup an everyday garden hose to the drain valve at the bottom of the tank. This can get messy, so run the hose to an outside drain or closest bathtub.
- The water level in the heater must be below the level of your TPR valve and there’s no foolproof way of determining what the water level is in the tank. A good rule of thumb is to drain your tank for the same amount of time that it takes to fill your bathtub. If you loosen the TPR valve and receive an involuntary drenching, you’ve got some more draining to do.
- TPR valves are meant to withstand constant pressure for extraordinary lengths of time and are rigorously tightened into place. You’ll need a pipe wrench, patience and a good amount of elbow grease to remove it. If you have a PVC outlet tube attached to your TPR valve, remove it before attempting to take off the valve. The tube can be cleaned and reused with the new TPR valve.
- Remove the old TPR valve with your pipe wrench in a smooth but forceful motion. Yanking or jerking it hard at the wrong angle can damage your tank. It may take time and patience, but it will come off.
- Once removed, thoroughly clean the dirt, gunk and residue buildup in and around the opening. Hot water and soap should do the trick, but don’t hesitate to use something stronger if necessary to get a clean surface for a good fit. Your old TPR valve is of no use to anyone, so toss it in a dumpster.
- Apply plumbers Teflon tape or plumbers pipe dope to the threads of the new TPR valve. Carefully thread the new valve into the opening and tighten it down with your pipe wrench.
- Reattach the PVC outlet tube you removed and thoroughly cleaned in Step 5. Make sure the outlet tube is completely dry. Add some Teflon tape or a small amount of plumbers pipe dope to the outlet tube and attach it so that it’s facing down.
- Unhook the garden hose that you attached to the drain valve in Step 3 above. Turn the water back on to let the tank fill back up. Once the tank is full, carefully inspect the newly installed TPR valve for leaks and to make sure it’s seated properly.
- Turn the breaker back on for electric water heaters and turn the knob from “pilot to on” for gas. Visually check to make sure the pilot light is working on gas water heaters. Once the water has been reheated, recheck the TPR valve for leaks.
