116 – Pressure Testing a Tank for Leaks

PRESSURE TESTING A TANK FOR LEAKS (#116)

Using Water to Pressure Test a Tank for Leaks

Note: This test is to be done when the water heater is hooked up to a plumbing system or water supply.

To pressure test a water heater for a leak in the tank, the only instrument you need is a water pressure gauge. The object of the test is to see if there is a significant drop of pressure which would indicate a leak in the tank.

To conduct a pressure test, follow these steps:

  1. Install a pressure gauge on the drain valve outlet of the water heater and then open the drain valve. This will give you a pressure reading of the water heater.
  2. Close the cold-water inlet shut off valve to the water heater. Make sure all of the hot water fixtures are turned off. This will create a closed system. Tank pressure in PSI:      
  3. Turn the thermostat up until the main burner or heating element comes on. Let the pressure in the tank increase 15 to 20 PSI. This will happen quickly, so be sure to keep an eye on the pressure gauge. Turn the thermostat down, shutting off the water heater. Tank pressure after rise in PSI:       
  4. Watch the pressure gauge to see if it holds pressure or drops off significantly.
  5. If the pressure gauge drops off significantly and no leaks are found in any of the water connections or fittings, then it is an actual tank leak. If the pressure holds for a period of time (15 minutes), then the tank is not leaking. If, when doing Step 3 you cannot get the pressure to rise, this may indicate that there is a hot water fixture open in the system or the leak in the tank is significant enough to not allow any pressure buildup. Tank pressure in PSI after 15 minutes:       

Using Air to Pressure Test a Tank for Leaks

Note: This test is to be done when the water heater is hooked up to a plumbing system.

To pressure test a water heater for a leak in the tank, you will need a pressure gauge, valve stem with Schrader valve and the miscellaneous fittings to adapt to the threaded connections of the tank. You will also need an air source such as a nitrogen tank or air compressor. The object of the test is to see if there is a significant drop of pressure which would indicate a leak in the tank.

To conduct a pressure test, follow these steps:

  1. Install caps to make the tank a sealed vessel. One of these openings should be adapted to a pressure gauge and one should be used as an air inlet/valve stem. This will allow you to pressurize the water heater.
  2. Pressurize the tank to 50psi. Tank pressure in PSI:     
  3. If the pressure gauge drops off significantly and no leaks are found in any of the connections or fittings, then it is an actual tank leak. If the pressure holds for a period of time (15 minutes), then the tank is not leaking. If, when doing Step 3 you cannot get the pressure to rise, this may indicate the leak in the tank is significant enough to not allow any pressure buildup. Tank pressure in PSI after 15 minutes:      

Always use caution when performing these tests. Pressure buildup is a potentially dangerous situation.

These tests should be conducted by a professional contractor.

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