How to Test the Safety of Your Hot Water Tank

There are four preliminary steps to ensure safety of yourself and your property.

First locate the water shut-off valve for the cold-water inlet on the water heater. Sometimes this is difficult to do in an older house with an old hot water tank. I have to shut mine off at the water meter out by the street.

Second find the shut off for the gas if your heater is natural gas powered or the electric breaker for the water heater (should be labeled) if it is electric. Some water heaters may have electrical controls closer that the electric breaker. Mine has to be turned off at the breaker.

Third find the phone number for a plumber who is located close to you that takes emergency calls. It would be best to do your testing during business hours on a weekday so it is easier to get help if you need it.

Fourth protect yourself from hot water. The water shooting out from a relief valve will be very hot. Be sure you are not where it will contact you during the test.

Test the safety of your hot water tank at least once a year. A good time to do this is the day of the time change while you are doing other once a year safety chores such as changing the batteries in the smoke alarms.

Testing the temperature/pressure relief valve may not be as easy as it sounds if you have a very old water tank or if the relief valve is non-standard. Other problems can be caused by improper installation or by covering up the relief valve with insulation. Note the different types of problems you may encounter and how to deal with them here: http://www.inspectapedia.com/plumbing/Water_Heater_Relief_Valves.htm

The way to test the T/P relief valve is to lift the lever or test handle that allows the water to escape. To keep the water from shooting out and scalding you there should be a drain line attached to the T/P relief valve that extends to the floor and a drain.

There should be information stamped on the T/P valve and also on the water tank nameplate. Be sure the information matches. You need to verify that the capacity of the valve is adequate and that the pressure setting is lower than the operating pressure of the water tank.

When all the preliminary precautions have been taken it is time to do the actual testing.

First clear every thing away from the area around the overflow pipe and away from the floor drain.

Second lift the test handle for about five seconds or until the water comes out the end of the pipe clear.

Third release the handle and wait a few minutes to make sure it has quit running. If it continues to let the water flow out you can quickly lift and lower the test handle several times to reseat the pressure relief valve.

Fourth if the valve continues to leak call your plumber to have it replaced.

Fifth While you are conducting the test, look for these five danger signs:

1. A valve that does not open easily.

2. Corrosion on the stem of the valve

3. Water leaking from around the valve stem.

4. Water leaking from the drain valve when the T/P valve is in the closed position.

5. A valve that does not close normally after being tested

Again I want to stress that the water from the T/P relief valve can be exceedingly hot. It is very important that they are installed correctly and with the proper size overflow pipe that is piped down to a floor drain. Avoid contact with the water to prevent burns and keep the water contained to prevent property damage.

Information in the article is taken from the Washington State Department of Labor and Industries publication F620-048-000 [06-2009], and from http://www.inspectapedia.com/heat/ReliefValves.htm . More information can be obtained from this site.