If your electric hot water heater fails to heat or only warms water, it could have a defective element. An electric water heater operates with two elements: upper and lower. The upper element maintains the temperature of the lower element.
In many cases, the upper element will go out first. A defective lower element may produce some hot water. A simple test can pinpoint a defective element. Here are tips to test electric hot water heater elements.
Prepare to Work
- safety glasses
- work gloves
Check to see if the breaker tripped. Hot water circuits are commonly double switches. A tripped breaker moves to "off," or halfway between"off" and "on."
Reset the breaker by pressing it to "on." It will usually click when it is reset.
Check the red reset button on the unit, press it back out, and test the water. This button often trips when the water gets too hot. If this step doesn't work, proceed to test with a multimeter.
Access the Elements
Shut off the breaker from the breaker box. The elements have an access panel, which is a rectangular cover on the front or side. Some models may have two panels. Detach the screws with a screwdriver, and set them aside.
Remove the insulation. Don't touch insulation with bare hands. Look for the element wires and disconnect one wire from each element. Removing one wire prevents a false reading.
Push the wire aside, so it won't touch the terminals (round, black objects with silver screws). Disconnect the plastic safety cover on the element, which should snap off.
Test the Element
Look for a label that has the voltage rating and wattage for the element. The ideal reading is the square of the voltage divided by wattage. For example, if the voltage is 250 and the wattage is 2000, multiply by 250 to get 62,500. Divide 62,500 by 2000, which is 32.50.
Set the multimeter on the lowest Ohms setting, or RxK1 (resistance times a thousand Ohms). Attach the black test probe to a terminal screw, and attach the red probe to the other screw. Connect another test probe to the metal tank.
A good element will give a reading of "O.L," or a reading within +/-20% of the calculated ideal reading. A very high reading means the element is faulty. Unscrew the probes, and attach the test probes to the other screws on the elements.
Reattach the panels, and restore power. If you got an "O.L" reading or you still can't find the problem, contact an HVAC/plumbing service.