If your water heater suddenly produces less hot water - and you haven't added a teenager to the household - you've probably burned out one of its heater elements. But don't worry. Unless the tank is leaking, it isn't dead. Heater elements are designed to be replaced, and it doesn't require a plumber to do so. Read on to find out how.
Determine which of the two elements needs replacing. If you get plenty of water but it's not as hot as it used to be, the upper element is shot. If you still get hot water but much less than you used to, the lower element is gone.
Shut off the water heater circuit breakers - usually a pair of 30-amp breakers linked together. If you are not sure which they are, switch off the main circuit breaker at the top of the entrance panel. Attach a note to the panel telling others to leave the power off.
Shut off the water heater's cold water supply valve.
Turn on a hot water faucet to provide air for draining the tank.
Connect a garden hose to the heater drain valve, lead the end to a floor drain, a toilet, or outside, open the drain valve and completely drain the tank.
Remove the appropriate access panel, uncover the thermostat and element, and remove the plastic terminal shield.
Loosen the terminal screws on the element and disconnect the wires.
Remove the old element, which will be one of these two types: Screw-in type: Turn the element counter-clockwise using an element wrench (available at a hardware or home center) or a 1-1/2" socket wrench. Bolted-on type: Turn the four 3/8" bolts counter-clockwise. Save the bracket holding the thermostat in place for reuse.
Clean the area of the tank under the gasket with a toothbrush or brass brush.
Take the old element to a hardware store or home center and purchase a replacement of the same type, voltage, and wattage (printed on the head of the element).
Install the new element: Screw-in type: Slip the gasket over the element threads and tighten the element clockwise using the element wrench or 1-1/2" socket wrench. Bolted-on type: Install a gasket (use only one, even if two are provided). If the gasket is round, insert it into the tank recess. If the gasket is flat, slide it over the heating element and align its bolt holes with those in the tank.
If the element is marked "top" or "up," turn it to the correct position.
Insert bolts through the holes in the thermostat bracket, then the upper pair of holes in the element and gasket, then into the upper holes in the tank.
Insert the other two bolts into the lower pair of holes in the element and tank.
Tighten all bolts hand-tight. Then tighten bolts alternately with a wrench. For the round gasket, tighten until the flange of the element contacts the tank; for the flat gasket, tighten a quarter turn past hand-tight.
Close the drain valve, remove the hose and turn on the water supply to the tank.
Leave the hot water faucet on until water flows steadily, then turn the faucet off.
Check the heater element for leaks. If there is a leak, try tightening the element or the bolts 1/4 turn. If the leak persists, repeat steps 3 through 5 and 8 through 14, making sure the gasket area is clean and the gasket is positioned properly.
Reconnect the wires to the element terminals.
Replace the plastic terminal cover, insulation, and access panel.
Check the hot water faucet once more to make sure the tank is full and there is no air in the water flow. Air in the water heater may result in the element overheating and burning out.
Restore electric power, remove the note, and treat your spouse to dinner with the $125 you saved by not calling a plumber.