Heating elements on electric hot water heaters sometimes fail long before the water heater, but replacing them in a hot water heater is an easy DIY repair.
If your electric hot water heater is slow to heat, runs out of hot water faster than it used to, or doesn’t deliver any hot water at all, there’s a 90 percent chance that simply replacing one or both of the heating elements will solve the problem. The fix is straightforward, and replacement elements are inexpensive ($8 to $20) and readily available at home centers, hardware stores and appliance parts dealers.
We’ll show you how to test the heating elements, remove one if it’s bad, and install a new one. Just keep in mind that water heaters have a typical life span of 10 to 15 years. If your heater is approaching old age, replacement may be smarter than repair.
Of course, there are other potential causes of a lack of hot water. Before you test the elements, check to make sure the circuit breaker is on and not tripped. Also press the reset button on the high-temperature cutoff located just above the upper thermostat. Resetting either the circuit breaker or the high-temperature cutoff may resolve the problem, but the fact that they were tripped in the first place may indicate an electrical problem. If they trip again, test the heating elements.
If the heating elements are good, the problem could be with the thermostats or cutoff switch. Testing is complicated, but since they’re inexpensive—about $20 for both thermostats and the cutoff switch—you could simply try replacing them.
Turn off the power at the circuit breaker and remove the metal covers to expose the thermostats and elements. Make sure the power is off by touching the electrical connections with a noncontact voltage detector.
You don’t need electrical experience to check and replace the heating elements. But you do need to make very sure the power is off before you perform any tests or repairs of your hot water heater.
First, find the circuit breaker in the main electrical panel that’s labeled for the water heater and switch it off. Then go back to the water heater and test for power with the non-contact voltage detector. Make sure the tester is working by putting the tip into an outlet you know has power. The tester should indicate power by lighting up or beeping.
Now test the wires leading into the water heater. If they’re covered by metal conduit, the tester won’t read voltage. Instead you’ll have to remove the metal thermostat cover on the side of the water heater, pull out the insulation and hold the tester near the wires leading into the top of the high-temperature cutoff switch (see Figure A).
Test both hot wires. Then hold the tester against the metal water heater shell. If the tester doesn’t light up, it’s safe to test the elements.
Most residential electric water heaters have two heating elements: one near the top of the tank and one near the bottom. Power enters the top and runs to the high-temperature cutoff switch, and then to the thermostats and elements. The top and bottom elements are controlled by separate thermostats. When the water on the top of the tank is hot, the top element turns off and the lower one heats. The upper and lower heating elements never come on at the same time.
Clip the alligator clamp onto one of the element screws and touch the other screw with the tester probe. If the tester doesn't light, replace the element.
For this you’ll need a continuity tester ($5 to $10). It’s basically a light bulb and battery with two wires attached. Touching the end of each wire to a continuous circuit will cause the bulb to light. You’ll find both of these tools near the electrical testers in any hardware store or home center. You may also find a continuity tester called a “water heater tester” near the replacement elements.
If you own and understand a volt-ohm meter, you can test with it instead. To expose the elements for testing, remove the two metal covers, the insulation and the plastic covers on the side of the water heater.
First perform a continuity test to see if an element is burned out. Electricity won’t flow through a burned-out element. Disconnect the wires from the terminal screws. Then connect the alligator clip to one terminal and touch the probe to the other one (photo 2). The tester should light up, indicating a complete circuit. If there’s no light, the element is bad.
Clip the alligator clip to one of the element screws and touch the tester probe to the element mounting bracket. Repeat on the other screw. If the tester light comes on either time, there's a short. Replace the element.
Next, test to see if the element is shorted out. If the element has a short, power will flow through the metal tank of the water heater. With the wires still disconnected, touch one probe (or connect the alligator clip) to one screw terminal and touch the other tester probe to the element mounting bracket (Photo 3). Repeat the test on the second terminal. If the tester lights on either test, the element has a short; replace it. Test both terminals on both elements.
Rarely, both elements will test OK, but you’re still not getting hot water. Try pushing the button on the “high-temperature cutoff,” located just above the upper thermostat. It may solve the problem, but if the problem recurs, check your heating elements.
Drain the water from the tank and unscrew the old element using a heating element wrench. You’ll need a long, sturdy Phillips screwdriver to turn the socket. If it won’t unscrew, use a cold chisel and hammer to loosen the threads.
Thread the new element into the water heater and tighten it with the heating element wrench. Reconnect the wires, making sure the connections are tight. Replace the insulation and metal covers.
To replace an element, start by draining the tank. With the power still turned off, close the cold-water inlet valve (Figure A). Open the hot water faucet in the kitchen. Then connect a garden hose to the drain valve and open it to drain the tank. For thread-in–type elements like we show here, you’ll need a water heater element wrench ($5 at home centers and hardware stores).
Try unscrewing the bad element by turning it counterclockwise (Photo 4). If it’s stuck, you can try breaking it free with a cold chisel and ball peen hammer or a small maul. Set the chisel at an angle against the nut so that pounding on it will turn the nut in a counterclockwise direction. Then install the new element, using the wrench to tighten it, and reconnect the wires (Photo 5). Close the drain valve and fill the tank before switching on the circuit breaker.
If testing reveals the elements are good, the thermostat may be faulty. The thermostat testing procedure is complex, so we recommend simply replacing the thermostat(s). You don’t have to drain the tank to replace a thermostat. Simply remove the old thermostat—they’re usually held by a metal clip—transfer the wires to the corresponding terminals of the new thermostat, and attach the new thermostat.
Replace your heating element with one of the same wattage. If your old element isn’t labeled with the wattage, refer to the nameplate on the water heater or your instruction manual, or search online using the model number from the nameplate.
Heating elements are held to the water heater either with a large thread and nut as shown here or by four bolts and nuts. Most home centers stock the version we show, but you can buy an adapter kit if you’re replacing the four-bolt version.
Simple U-shape elements are the cheapest. More expensive low-density elements are usually folded back like the one shown in Photo 5. These provide the same amount of heat but spread out over a larger surface area, which lowers the surface temperature, making them less prone to mineral buildup.
If your old element was caked with minerals, replace it with a low-density element for more efficient operation and longer life.
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Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
You'll also need a hose, an electrical continuity tester and a heating element wrench.
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