DIY Water Heater Testing and Repair

A one-hour DIY repair that will save you the cost of calling the plumber

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Introduction

Heating elements on electric water heaters sometimes fail long before the water heater, but replacing them in a hot water heater is an easy DIY repair.

Tools Required

  • 4-in-1 screwdriver
  • Needle-nose pliers
  • Non-contact voltage tester

Materials Required

  • Heating elements

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. Water heater repairs are 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.

Learn how to regulate your water heater here.

Other Causes of Water Not Getting Hot

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.

Video: How to Test Your Water Heater Element

Do It Yourself in 6 Steps

Step 1

Remove the Cover Plates

  • Turn off the power at the circuit breaker.
  • Remove the metal covers to expose the thermostats and elements.

Step 2

Test the Wires

  • Test the wires leading into the water heater.
    • Note: If the wires are covered by metal conduit, the tester won’t read voltage. 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.
  • Hold the tester against the metal water heater shell.
    • Note: If the tester doesn’t light up, it’s safe to test the elements.

What's Inside a Water Heater and How It Works

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.

 

Step 3

Test Continuity for a Burned-Out Element

  • Disconnect the wires from the terminal screws.
  • Clip the alligator clamp onto one of the element screws.
  • Touch the other screw with the tester probe.
    • Note: If the tester doesn't light, replace the element.

Step 4

Test for a Short Circuit

  • Clip the alligator clip to one of the element screws.
  • Touch the tester probe to the element mounting bracket.
  • Repeat on the other screw.
    • Note: If the tester light comes on either time, there's a short. Replace the element.

The Secret of the Red Button

Rarely, both elements will test okay, 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.

Step 5

Remove the Bad Element

  • Close the cold-water inlet valve.
  • Open the hot water faucet in the kitchen.
  • Connect a garden hose to the drain valve and open it to drain the tank.
    • Note: For thread-in–type elements like we show here, you’ll need a water heater element wrench ($5 at home centers and hardware stores).
  • Unscrew the old element using a heating element wrench.
    • Pro tip: 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.

Step 6

Install the New Element

  • 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.

Buying Heating Elements

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. 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.