How to Fix a Leaky Hot Water Heater Pressure Relief Valve- Know it

What is a Temperature Relief Valve?

When water is heated, it evaporates and turns into steam. Keep heating this steam and it will also expand and look for somewhere to escape from. Pressure builds up and due to the resulting force, managing to break through is so powerful it would literally be able to blow up inside the house with the force of a missile (steam will manage to break through nearly anything, if not kept in check, even steel). Obviously, nobody wants their house blown up and water tank production companies could be suffering millions of losses in damages daily, which they also don’t want.


In comes the little guy. The temperature and pressure relief valve (the TPR valve), often called the temperature and pressure valve (T&P valve) is a water heater safety device designed to relieve the pressure from water heaters in case of an extreme temperature/pressure rise (anything above 150 psi, is explosive, if you’re curious). As you can guess, it’s pretty important that the T&P valve works properly, and in perfect correspondence with the water heater thermostat.

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Why is water leaking out of the temperature relief valve?

Now that you realize its importance, we finally come down to the million dollar question (actually, it will cost like fifteen dollars to fix, but you get the idea). The first thing you should keep in mind is that most times, the source of the problem is usually with the temperature pressure valve itself, especially if you happen to own a hot water heater with an old relief valve.

As before stated, one reason temperature pressure relief valves will release water slowly if there’s too much pressure in the tank, but this only happens in closed water systems. If you’ve got a leak, it won’t work properly.

The other possible reason could be that the water-pressure regulator valve may also be broken.

It’s recommended that you periodically test the temperature pressure relief valve by lifting its lever to make sure it is working – if it is, hot water should come out of the discharge pipe and when you release the lever, it should snap back down. Doing this with a broken or old valve can cause it to leak—if it does, you’ll need to replace it.

Why is the relief valve releasing large amounts of water?

This is a normal occurrence that happens when the valve is opened because of high temperatures. To fix this, you first have to check the value on the temperature pressure valve.

How to check a TPR valve

  • In order to check for a leaking valve, feel the drain line with your hand to see if it’s too hot. The drain line may be a little warm near the valve, this is completely normal. If the line is hot, the relief valve is opening.
  • Raise the test lever on the relief valve where you should hear water discharging out of the relief valve drain line. If you do, then no worries, your valve is working properly. If you don’t hear a discharge sound or your test lever won’t raise (don’t force it), you’ll need to replace the relief valve as soon as possible.

How to replace a water heater temperature pressure relief valve

  • Depending on the kind of heater you have, either turn the water heater breaker off for an electric heater or set the temperature to the lowest setting on a gas water heater.
  • Turn the control knob to the factory pilot setting.
  • Turn the water supply off at the water heater.
  • Turn on the nearest hot water faucet to relieve the pressure on the tank. If the pressure relief valve is mounted on the side of the tank, you have to drain the tank until the water level is below the valve. If the relief valve is mounted on top of the tank you’re okay to proceed.
  • Remove the drain line that’s attached to the relief valve.
  • Cut the line and unscrew it from the relief valve.
  • Remove valve with an adjustable wrench and tap the end of the wrench with a hammer to loosen the valve.
  • Lift temperature pressure relief valve from water heater.
  • Remove the old relief valve and using teflon tape or pipe dope, install the new relief valve.
  • Reinstall the valve drain line, and if your drain line is a CPVC pipe be sure to use CPVC glue to couple the line back together. Give the glue 2 hours to dry before testing the new relief valve.
  • Refill the water heater. Leave the hot water faucet open until all the air is out of the line.
  • Check for leaks, and if it’s working just fine, turn the power on for an electric water heater or for a gas water heater, set the control knob back to the on position.
  • Turn the temperature control knob to the normal setting.

That being said, you should have a fully functional hot water heater pressure relief valve, but if the problems persist, why not check out some tankless water heater reviews online and get yourself one? They’re much more efficient, affordable and require less maintenance than any gas or electric water heater.

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