Hot water is a modern necessity. Learn how to drain a gas or electric water heater and do simple maintenance and repair to the pressure relief valve, tank or pilot light. Also learn how to work safely with gas and electric water heaters to keep them working efficiently.
Both gas and electric water heaters have a safety device called a temperature and pressure relief valve, or T&P valve for short. In the event the tank overpressurizes, the relief valve opens and releases the pressure. If the valve doesn't operate correctly, the tank can overpressurize and explode.
Always wear gloves, goggles and other protective clothing while performing maintenance on your water heater.
Turn off the electricity to the water heater or turn off the gas to extinguish the pilot light. Shut off the cold-water inlet to the water heater.
Position a bucket to catch water from the pressure relief valve. Pull the trip lever on the valve. You should hear a slight rush of air or see some water and vapor exit through the pressure relief valve. If you don't, drain the tank and replace the valve.
To replace the valve, remove the discharge pipe and unscrew the valve from the water heater. Note the stem length and buy an exact replacement. Screw the new valve into place, tightening with a wrench. Reattach the discharge pipe, turn on the water and either reconnect the electricity or restart the pilot light according to the manufacturer's instructions.
Sediment buildup in the tank can reduce your water heater's energy efficiency and also clog your water lines. Avoid these problems and increase the life of your unit by flushing the tank each time you check the pressure relief valve.
Turn off the electricity to the water heater or turn off the gas to extinguish the pilot. Shut off the cold-water inlet to the water heater.
Connect a garden hose to the tank's drain valve. Locate the draining end of the hose in an area that won't be adversely affected by the scalding hot water.
With the pressure relief valve open, open the drain valve and allow the tank to drain completely. Completely draining the tank ensures that you've removed all of the sediment possible.
Close the tank drain valve, disconnect the hose from the valve and close the pressure relief valve. Open all the hot-water spigots in the house, and turn on the cold-water inlet to the tank.
Close each hot-water spigot as water begins to flow from it. After all the spigots are closed, turn on the electricity to the water heater, or turn the gas switch to run.
With the gas valve in an “on” position and the control knob set to “pilot,” press the knob and push the igniter button. The light will blink when it’s lit and you should see a small flame through the view pane. Set the temperature to 120 degrees Fahrenheit.
Read and follow your manufacturer’s lighting instructions for more detailed instructions on lighting the pilot.
Newer water heater models have a smaller pilot light, which may be hard to see. If so, darken the room and look carefully through the sight glass in order to see the pilot light.
The first time a gas water heater is lit it may produce condensation. You may hear dripping sounds or see a small puddle of water in the drain pan. Condensation is normal and will go away once the water heater has reached its normal operating temperature.
The most common problem with electric water heaters is turning the power on before the tank is completely full of water. If this happens, the upper heating element will burn out, and you’ll have no hot water until the upper element is replaced.
To replace the top or bottom heating element, disconnect power to the unit and drain the water heater tank. Disconnect the wires from the element and loosen it using an element wrench. Unscrew the element and pull it straight out. Insert the new element in its place and tighten using the element wrench. Reconnect the wiring and prepare to refill the tank.
Open a hot-water faucet all the way and let the water run for 3 minutes. This ensures all of the air has been removed and the tank is completely full of water. When the tank is full, turn the power on. If you don't have hot water after two hours, check to make sure the unit is getting the correct voltage. (See the unit’s label for power requirements.) No electric power or the wrong voltage causes many electric water heater problems. An electrician may be needed to solve wiring / power problems.
Most leaks are caused by faulty water supply connections. Use good materials, proper techniques and check your work carefully. Compression fittings are easier to install for DIYers than copper pipes, which need to be soldered.
Drips from the temperature and pressure (T&P) relief valve discharge pipe usually mean a thermal expansion tank is needed.
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