Poor water-heater performance and breakdowns or other serious problems often can be prevented through maintenance.
For example, a water heater’s pressure-relief valve should be checked for proper operation at least once a year. The function of the valve, on or near the top of the tank, is to allow water to escape from the tank if there is a dangerous buildup of temperature and pressure in the water heater. A faulty pressure-relief valve can result in an explosion of the water heater.
Specific directions for checking the pressure-relief valve can be found in the owner’s manual for the water heater. In general, checking the valve requires lifting a small handle on the end of the valve. This should cause some water to flow from the valve. Since the water released is sometimes very hot, use extreme care to avoid burns. I wear protective gloves and catch the water in a can when performing this check.
When the handle is released, the pressure-release valve should close and shut off the water flow. If the valve continues to release water after a check, it should be replaced with an identical valve, which requires shutting off and draining the heater.
If water flows from a pressure-relief valve at other times, the water heater should be checked by a qualified service person to correct the conditions that cause pressure buildup.
Some experts recommend periodic draining of some water from the tank to help reduce sediment buildup. This is done from a faucet-type valve at the bottom of the tank. If sediment is a major problem and causes poor operation of the heater, the tank might need to be drained and flushed about every six months.
Specific instructions for draining a water heater can be found in the owner’s manual.
For an electric water heater, the first step in draining is to turn off the power to the heater. If the heater is fueled by gas, it should be set to “pilot” to keep it from coming on during draining. For either type of heater, close the supply valve that lets cold water enter the heater tank (this valve is normally in a pipe above the tank). The cold water can also be turned off at the main valve near the water meter or pump.
Attach a hose to the drain valve at the bottom of the tank and run it to a drain or other outlet. Open a hot-water faucet near the water heater, and leave it open, to allow air to enter the tank as water drains out. Finally, open the drain valve to release water from the tank.
When the tank is empty, leave the drain valve open and open the cold-water supply valve fully to let water enter and leave the tank as forcefully as possible. Repeat this flushing action several times by turning the supply valve off and on, until water from the tank runs clear.
Complete the flushing by turning off the drain valve. Open the supply valve and let the tank fill (water will run from the hot-water faucet, previously opened, when the tank is full). Turn the electricity or gas back on.
Water heaters also should be drained when a home is not occupied for an extended period or if the heater is shut down during freezing weather. This will obviously save electricity or gas, and also help prevent accidents. If an operating water heater or its piping springs a leak during a long absence from a home, serious damage can result.
Electric water heaters sometimes develop sudden heating problems and produce only lukewarm water. This often can be traced to the tube-like elements that heat the water.
Most electric heaters have two elements, one near the top and one near the bottom of the tank. The bottom element, which does most of the water heating, generally burns out first or performs poorly because of mineral buildup on its tubing.
A dirty or burned-out element is fairly easy to clean or replace, but the procedure must be done with extreme care to prevent electrical shock or damage to the heater. Never attempt to clean or replace an element without consulting and carefully following the directions in the owner’s manual.
Electricity to the heater must be turned off, and the tank drained, before an element can be removed for checking. New heating elements are available at appliance-parts stores and some home centers.
A new element must match the original.
