Paul’s Hardware Blog

One of the most common questions we are asked  is, “my water heater is leaking. How do I fix it.” The question is more complicated than it sounds. I am inspired to write this post today because, guess what, my water heater is leaking. I didn’t really expect that my first entry would be so entertaining (boring) but it is a really common problem. So, here goes.

There are usually 4 things that cause a water heater to leak.

1. A failed tank. This one is pretty easy to spot since there is usually a flood coming out of the bottom of the water heater. There isn’t any good fix other than replacing the water heater.

2. A bad temperature and pressure release valve. The temperature and pressure release valve is a really important thing. If, for some reason the water heater malfunctions and the water gets too hot and boils there could be a really serious explosion. (see video below) Don’t EVER plug, cap or block in any way, a T&P valve. It will release water if the pressure in the tank goes above a certain amount (usually 150 psi) or the temperature goes above a specified number (usually 210 F).  Sometimes these valves fail and release water when the temperature and pressure are normal.  In that case you just replace the T&P valve.

 2. A bad Pressure Reducing Valve. PRV  The pressure reducing valve controls the amount of pressure in the plumbing system of your house.  It is usually located in a basement or crawl space where the main water line enters the house.  They can also be outside the house in a box in the ground. The pressure in the water main is usually higher than the 50-70psi that is recommended for home equipment and appliances.  If the PRV fails, the pressure in the house will rise.  If it gets high enough the T&P valve on the water heater will leak, toilet valves will fail and faucets will drip.  The question is how do you know if the dripping  is the PRV or the T&P?  (I’ve always thought it is funny how plumbers use initials for things. Its almost like another language)  You have to test the water pressure in the house.

To test the pressure I used a recording pressure valve with a fitting for a garden hose.  I attached it to the drain on the water heater.  You need to use a valve that records the highest pressure reached since it really goes up during the night.  I took this picture in the mid morning.  The pressure was a little above 50psi.  During the night though it had reached 150psi.  I had a mini flood.  Since the pressure went substantially above 50psi I knew that the problem was my pressure reducing valve.  I was in a hurry and didn’t want to drag out a torch and solder (I have copper pipes) so I used Sharkbite fittings.   They have to be one of the best inventions in years.  You just slide them on the pipe and they seal.  It took me 12 minutes to finish the job. 

4.  Thermal Expansion.  When water is heated it expands.  In the old days it wasn’t really a problem.  The water back flowed into the water supply (municipal or tank).  This can be dangerous so most localities passed regulations requiring back flow preventers.  The water has to go somewhere.  The answer is a thermal expansion tank.  It uses an air cushion and diaphragm to absorb excess pressure.  Sometimes these tanks fail.  There is an air valve (like a car tire) on the bottom of the tank.  If when you release a little air you get water you know that the tank is defective.

So now, thankfully, I have dry basement again.

This post is for informational purposes only.  I am not a plumber.  You should not attempt any repairs yourself without checking your local codes and regulations.

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