Electric hot water heater problems
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.
Test the elements
1 of 1Photo 1: Remove the cover plates
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.
Electric hot water heater cutaway
Figure A: What's Inside 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.
Test for a burned-out element
1 of 1Photo 2: Test continuity for a burned-out element
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.
Test for a shorted element
1 of 1Photo 3: Test for a short circuit
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.
Occasionally, pressing the reset button may solve the problem.
The Secret of the Red Button
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.
Replace an element
1 of 2Photo 4: Remove the bad element
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.
2 of 2Photo 5: 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.
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.
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
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.
Video: How to Test Your Water Heater Element
We've all been there, get in the shower only to realize that you have no hot water. Jeff Gorton, an editor at The Family Handyman, will show you the most common reason you have no hot water and how to correct the issue yourself.
