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What is a T & P Valve and Why is it Important?

Tuesday, March 21st, 2017

Most households depend on a water heater to produce hot water when needed for a variety of chores around the home. Chances are you use hot water every, single day to bathe, clean dishes and wash your dirty clothes. Homeowners would be wise to gather a basic understanding of its safety features so they can identify the signs of a serious problem should it occur. The following post will define the primary function of a T & P valve and the signs that point to a pending problem.

What Is the T & P Valve?

A temperature and pressure “T & P” relief valve is a critical safety feature built into your water heater. As water is heated, it expands, which can create excessive pressures within the water heater storage tank. Too much pressure and the tank can explode, which can cause property damage and/or serious injury. The T & P safety valve’s primary function is to release excessive pressure should it exceed 150 PSI or if the temperature rises to 210 degrees F or above. If either of these instances occurs, the valve will open, discharging water to relieve pressure and preventing a mishap.

The T & P valve is often located on the top of the unit but can also be side mounted. The valve screws directly into the tank and should be connected to a discharge line leading to the homes exterior and in an area where if it should open, the hot water will be clearly visible. The discharge line prevents unnecessary water damage and/or scalding should the valve open and discharge water.

If your T & P valve has opened, you should take it as a sign something is malfunctioning with your water heater. Under normal circumstances, the valve should never open and discharge water. The most common reasons your water heater is discharging water are the following:

  • Thermal expansion
  • Increased system pressure
  • Low temperature relief
  • Malfunctioning thermostat
  • Malfunctioning heating elements

If your T&P valve has opened, contact your plumbing contractor immediately.

Annual T & P Inspection

You would be wise to enlist your plumbing contractor to test the safety valve at least once a year. They can trip the valve manually to verify waterways are clear and that the valve seats properly when closed. After tripping the valve, if it continues to leak, it could be a sign of mineral deposit or buildup and is a solid indicator that the valve should be replaced.

For answers to your plumbing questions, contact The Pink Plumber today.