Warning About Your Temperature and Pressure Relief Valve

They say that dynamite comes in small packages, and when it comes to protecting your plumbing system and the safety of your home and family, that adage holds true. One of our technicians recently found an incorrectly installed Temperature and Pressure (T&P) Relief Valves in a client's home that could easily have caused serious damage.

What is a Temperature and Pressure (T&P) Relief Valve? - Master Plumber Explains

The function of a Temperature and Pressure (T&P) Relief Valve is to detect high water temperatures and to relieve pressure that builds up inside your water heater. It provides a short-term solution, while performing the important function of preventing long-term issues from taking the toll on your home and your family. It is a safety measure that is installed to remedy your system in the event of malfunction.

How it Works

"Water expands with heat," explains our City of Toronto licenced plumber, who specialises in plumbing installations. "Your standard water heater, which holds 40 gallons of water will expand by roughly half a gallon when it operates at the set thermostat. The additional volume must be released, or else the pressure in the water heater will increase."

When water in your water heater reaches 210 degrees Fahrenheit, the T&P valve starts discharging water, thus relieving the pressure at 150 psig. When you notice that the T&P valve is discharging water, it could indicate:

  • a faulty element or thermostat
  • too high temperature settings
  • excessive pressure or extreme temperatures
  • a faulty T&P valve
  • or thermal expansion.

Either way, you should call a Toronto plumber to take a look and diagnose the issue. He will check whether the T&P valve is releasing around one cup of water per 10 gallons of the heater's capacity in a single cycle. If it does, that means that thermal expansion is the cause. Some cities require thermal expansion camps to avoid this problem.

Plumber Explains Problems With Your T&P Valve

According to our Toronto plumber, your T&P valve is only a short term solution and it is crucial to have it seen to if it regularly releases water, it means that there is another issue that should be remedied.

In addition to signalling a more serious issue, the T&P valve itself can become faulty over time. If there is regular discharge, mineral deposits can build up on the valve seat, your valve will stop working.

Thermal expansion may cause your T&P valve to overwork, in which case you should consider replacing it. A Watts thermal expansion tank or a tankless water heater might provide a safer, long term fix that is in line with current City of Toronto plumbing codes.

Correct Plumber Installation of a T&P Relief Valve

As with all plumbing installations, there's always a right (and wrong!) way to install equipment. Incorrect installation will damage your water heater and put your home and family's safety at risk. Here are some tips from our master plumber Toronto:

1. During installation, the temperature-sensing element should be immersed in the top six inches of water in the tank.

2. The T&P valve can be installed in the tank's tapping, but should ideally be installed on the hot outlet service link.

3. Isolate the T&P valve from ambient conditions such as flue gas.

If your current plumber installation T&P valve is causing you any concerns, get in touch with your Toronto plumber who can help to diagnose the issue before it becomes a problem.

Written by Tanya Klien

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