If your electric water heater is not providing any, or very little hot water one possible cause is a faulty heating element. The element heats water inside the tank by creating resistance in an electrical wire, much like an oven element. You can easily test an element with a multi-meter for serviceability before spending money on a replacement, but you should at least be comfortable working with electrical components and know how to read an electrical multi-meter.
If your water heater suddenly stopped working you should first check the power to it at the fuse/breaker box, then with a multi-meter at the tank, also check the thermostat to see if the reset is tripped.
If your water heater only produces hot water for a few minutes, the dip tube may be to blame.
Testing the elements
To test the water heaters element follow these steps:
- Shut of the power at the breaker or if there is a disconnect box beside the tank, turn it off there.
- Remove the cover plate on the side of the tank with a screwdriver and test that the power is in fact off using a multi-meter.
- Look at the thermostat to ensure that it hasn't been tripped and reset if necessary.
- Locate the top element; usually under the thermostat, and remove the wires from it.
- Place your multi-meter on OHMS (Ω) to measure the resistance across the element. To make sure your meter is working touch the two leads together and it should read "0.0" OHMS.
- Place the two leads on the element's terminals and check for a resistance reading on the multi-meter. If the element is still good, there will be some resistance; which is what heats the water, if there is zero or 0.** then the element is bad and needs to be replaced. You may have to adjust your meter to a certain range in order to detect the resistance across the element.
- The actual formula to find the resistance is: watts / amps2 = OHMS (Ω) or volts2 / watts = OHMS (Ω). You can find this information on the electrical plate of your water heater.
- You can also use an amp meter to see if there is a draw on the element but the power must be on and the thermostat must be calling for heat.
Replacing the water heater element
If you've checked the element(s) and they are not working, it's time to get you hands dirty and replace them(actually it's not dirty work). Source out a replacement element from a plumbing supply store and give them a few details (Manufacturer, Model, electrical info). Before you spend any money on repair parts ask yourself if your tank will last a few more years or is it time to replace it?
- Turn off the power at the breaker and double check that the water heater with a volt meter.
- Start by shutting off the supply valve to the tank and draining out the water. You will have to open the lever on the relief valve to allow air into the tank.
- Unbolt and remove the element and gasket.
- Replace it the same way with a new one. Make sure you use a new gasket as well.