Water Heater Repair, Part 2 •• Some Blog Site

Water Heater Repair, Part 2

Sep

2010

This post is where I expand on step 1 from my earlier post on how to fix a water heater.

You need a multimeter. You must be able to measure resistance somehow. I know, it’s futile. Just ignore the bellowing guard.

Here goes:

Check for a failed element

Disconnect both wires from the heating element. Measure the resistance across the element (from one screw to the other). It should be a dozen ohms or so.
Repeat for the other element.
If either one is zero or a large number, that element is bad.

Check for a failed connection

With the wires still disconnected, measure the resistance between the element and the tank. It should be an open circuit (or a really really large number).
Repeat for the other screw and then for the other element.
If either one is a low number, then something is bad. It’s probably the element.

Check for a failed thermostat

Connect everything back together like it was. Do this only if your elements were fine. Then turn on the power and be careful.
Now you need to measure voltage. A multimeter will work, or you can use a dedicated AC voltage tester.
You must cause the water heater to think it needs to heat water. Turn on the hot water at some faucet, or turn up the thermostat setting very high.
Measure the voltage across the two screw terminals of the heating element. You should have 240V (or 120V, whatever you’re wired for).
Turn down that thermostat and turn up the other one.
Now measure that element’s voltage.
If you never get voltage to an element, then the thermostat is bad.
Note that the upper thermostat can prevent the lower thermostat from working. If you’re electrically inclined, you can re-wire the lower thermostat to take power directly from the line, rather than through the upper thermostat.

And, in case are wondering if you can tell just by looking if a water heater element is good or bad – yes, you usually can.

Good:

Bad:

Look for things like splits or cracks in the metal:

One more post coming soon – how to unscrew the heating element.

But the day of the Lord will come like a thief, in which the heavens will pass away with a roar and the elements will be destroyed with intense heat, and the earth and its works will be burned up.

2 Peter 3:10