Electric water heaters all come equipped with heating elements. These elements will often outlast the tank on the unit. However, with age, these elements can lose their ability to get as hot as they once did, or they can burn out altogether. If the tank is emptied and the water heater is powered on before the water covers one or both of the elements, an element can burn out in less than a minute.
When an element comes to the end of its life, it must be replaced. Most water heaters have one or two and sometimes three heating elements. Two heating elements is the most likely number to find. Large home stores like Home Depot and Lowes carry these replacement elements in their stock. Many local hardware stores also stock them or can order one within a few days.
Replacement elements are relatively inexpensive. The cost runs from about $9 to $20 each. Go to the store armed with the type of heater that you own and the model number. Elements fit a variety of water heaters. Find the ones that fit your unit and buy them. They are fairly easy to replace with just simple tools and a measure of common sense and care.
On the outside of the element is a hexagonal fitting about one inch in diameter. The store where you buy the replacement element will carry a tool to fit this. You may have a socket in your tool chest that will work. In addition to this tool, you will need a screwdriver.
Begin the project at your circuit box. Turn off the breaker or breakers that drive your water heater. This will be a 220 volt breaker. It will be double and may have two switches or one fat one. Some amateur electricians will use two 110 volt breakers in place of one 220 volt. If this is the case, there will be one breaker on each side of the box that controls the water heater.
If you have any doubts, have your circuit tested to make sure the power is off. In case you have no way to check the circuit, just disconnect the main breakers and turn off the power to the whole house.
You will now need to drain the water heater. Turn off the water to the water heater. Attach a hose to the valve at the bottom of the unit. Run this house outside to an area that is downhill from the water heater. If the heater is in the basement, you may have to catch the water in a bucket or run the hose to a sump drain. Should the water not drain from the unit easily, some other measures may need to be taken.
Start by opening the pop off valve at the top of the water heater. It may be that you are having the water held in place by a vacuum in the device. By open this second valve, it will let air in so the water can flow out. If there is no change in the flow at this point, you may have sediment that has built up in the bottom of the water heater.
Get a stiff wire like a clothes hanger. Remove the hose from the bottom valve. Slowly open the valve. If no water is coming out with the top valve open, use the wire and slide it carefully up the lower valve. Once the wire is inside the water heater, you should feel some resistance. Poke the wire back and forth until you see a little red or brown debris begin to seep out of the water heater through the valve. Pull the wire out and see if the water flows any better. If it is, attach the hose and let it drain for a while. You may have to do this several times.
After about ten gallons of water has drained from the tank, you should be able to remove the top element. Use the screwdriver and remove the wires that are attached to the element. Note where each wire attaches. Once the wires are loose, unscrew the element and pull it out of the water heater tank. If removing the element causes the tank to drain faster, leave it out until the water has drained from the tank.
Replace the element by carefully pushing the new element into the opening and screwing it into the tank. You may want to use a little pipe dope or Teflon tape to make sure that it does not leak. Once it is tight, replace the wires to the correct terminals.
Repeat the procedure for the bottom element with one notable exception. When you unscrew the bottom element, if there is a lot of sediment in the tank, it may have filled the tank to the level of the element. This will make the element a little hard to pull out. When you have removed it, if you can, try to reach through the opening and extract as much of the sediment as possible.
If it is really deep, remove the bottom valve from the tank and scrape most of it out through that opening. When you have removed as much sediment as possible, replace the valve. Now, you can finish installing the new element.
When the wiring is completed, make sure the pop off valve and bottom valve are shut off. Turn the water on to the tank. Go to a sink like the kitchen or bathroom and open the hot water valve. This will let air out of the tank so the water can fill it. It will take about ten minutes to fill the tank.
Once the water is running smoothly from all of the hot water faucets, your tank is full. Check for leaks. Tighten any fittings that seem to be seeping water until it stops. Replace the covers over the electrical connections. Go to the circuit box and turn on the power.
You should hear the elements as they start to heat up. Wait about an hours, and hot water should flow from your faucets. It may not be all of the way up to your preferred heat, but it will be much warmer than the normal tap water.