All water heaters have a temperature- and pressure-relief valve that is designed to prevent the water heater from exploding. Some manufacturers suggest testing the valve every six months or so by raising and lowering the test lever on the valve. This should produce a sudden burst of hot water from the drain line connected to the valve. More frequent testing can reduce the chance of a leak caused by mineral and corrosion buildup. However, if a leak results immediately after a test, simply operate the test lever several times to free lodged debris that might be preventing the valve from seating properly.

There are a few reasons why your valve is running all of the time -- wasting water and energy! The valve may be built up with corrosion. Try flipping the test lever up and down a couple of times and tap the stem using a hammer to seat the valve. If this doesn't do the trick, check to make sure that the thermostat (located on the controller) hasn't been turned up. It should be set on medium for the safest and most efficient operation. Excessively hot water will cause the pressure and temperature relief valve to open -- it's doing its job. Test the temperature of the water by using a thermometer in a glass filled with hot water from the tap. The temperature should not exceed 130 degrees.

Finally, excessively high water pressure can cause the temperature and pressure relief valve to leak. Residential water pressure should run between 30 psi and 55 psi. Pressure exceeding 55 psi can potentially damage cloths washers, dishwashers, ice makers and other water-supplied automatic appliances. Most homes have a water pressure regulator valve at the location where the water enters the building. You can test the water pressure by using a gauge available from the hardware store. Screw the gauge onto a hose bib and turn on the water. You can adjust the water pressure by turning a nut or screw on the pressure regulator.