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Why Is My Water Heater Pressure Relief Valve Leaking?

By February 14, 2020November 18th, 2020Plumbing
Leaking Water Heater Pressure Relief Valve

The water heater is known for its high heat and high pressure. The water heater temperature-pressure relief valve (TPR Valve), protects us from this high heat and pressure. So what is the TPR valve, why does it leak, and what should you do about it?

water heater diagram: TPR valve, dishcharge tube, and expansion tank.

What Is The Temperature Pressure Relief Valve (TPR)

The TPR valve, also called, a pressure relief valve is a specialized valve at your water heater. This valve is typically on the top or side of your water heater.

The valve functions by releasing water if your water heater becomes too pressurized. Since heated water expands, the water heater can become a ticking time bomb if we were to continually build pressure in your water heater.

Luckily for us, the water heater has many safety mechanisms that help protect us from an explosion and the TPR valve is one of them.

The Discharge Tube

As seen in the featured image, a TPR valve is required to have a discharge pipe/tube. This tube should be aimed straight to the ground and never go up. This is because hot water will come out of the TPR valve as it releases water. Therefore, extremely hot water should discharge to the ground for safety.

Additionally, if a pipe were to go up, water will have to work against gravity to empty. So, it is possible a slow drip of the TPR valve will collect water in the tubing and ultimately rust out the valve rather than empty it to the floor.

See the image below for a perfect installed discharge tube connected to a TPR Valve.

properly installed TPR valve and discharge tube.
Properly Installed Temperature/Relief Valve & Discharge Tube

By the way, here are the code requirements for discharge tubing in Florida:

504.6 Requirements for Discharge Piping

The discharge piping serving a pressure relief valve, temperature relief valve or combination thereof shall:

  1. Not be directly connected to the drainage system.
  2. Discharge through an air gap located in the same room as the water heater.
  3. Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air gap.
  4. Serve a single relief device and shall not connect to piping serving any other relief device or equipment.
  5. Discharge to the floor, to the pan serving the water heater or storage tank, to a waste receptor or to the outdoors.
  6. Discharge in a manner that does not cause personal injury or structural damage.
  7. Discharge to a termination point that is readily observable by the building occupants.
  8. Not be trapped.
  9. Be installed so as to flow by gravity.
  10. Terminate not more than 6 inches (152 mm) above and not less than two times the discharge pipe diameter above the floor or flood level rim of the waste receptor.
  11. Not have a threaded connection at the end of such piping.
  12. Not have valves or tee fittings.
  13. Be constructed of those materials listed in Section 605.4 or materials tested, rated and approved for such use in accordance with ASME A112.4.1.
  14. Be one nominal size larger than the size of the relief valve outlet, where the relief valve discharge piping is installed with insert fittings. The outlet end of such tubing shall be fastened in place.

Leaking Relief Valve

Now that we know how a TPR valve functions, we can better assess what to do if your pressure relief valve is leaking.

If your pressure relief valve is leaking, for the most part it is an easy fix.

Common Fix For a Leaking Temperature Pressure Relief Valve

Typically, the relief valve is malfunctioning so a replacement of the valve is in order.

This is a simple job. Here is a quick guide to follow:

  1. Turn off the water heater breaker.
  2. Shut off your water.
  3. Empty the water heater by draining the bottom and water inside your home.
  4. Remove the TPR valve and discharge tube by unscrewing with a wrench.
  5. Replace with a new TPR valve and discharge tube.
  6. Turn the water back on slowly and turn the water heater back on when it is full.

You can buy these relief valves on Amazon. Just be sure it is the right size!

Pressure relief valve from Amazon
Source

Video on How To Replace Your TPR Valve

However, if you do this step and the temperature-pressure relief valve is leaking again, it is most likely a separate issue.

Other Fixes For TPR Valve Leaks

If you completed the step above and you know the relief valve is functioning properly, it might be time to call a plumber.

This means the pressure is building up too much in the water heater and your water piping could be under stress.

Typically, the solution to this is through a bladder tank, also named an expansion tank. The expansion tank works by allowing more room for the heated water to expand too. Depending on your location and home, an expansion tank might be required by code.

Concluding

The pressure relief valve at your water heater can leak. If it does, for the most part it is an easy fix by replacing the valve.

However, if you find the relief valve to continue to leak even after replacement, you should contact a plumber for assistance. A licensed plumber will be able to evaluate your system and decide on installing an expansion tank or other solutions.

If you have additional questions, be sure to drop a comment below!

Aaron Shishilla

Author Aaron Shishilla

Aaron Shishilla is the youngest registered professional inspector in Florida. Coming from a family-owned home inspection company and now the marketing manager at Waypoint.

More posts by Aaron Shishilla

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