0

Edit: adding make and model: It's a Rheem Marathon MR85245 (85 gallon).

My water heater has two elements. Reading online, the top element is "resistored" or should be at least. From what I read this means it has a resistor integrated in it that prevents runaway and keeps the element from instantly failing if it is dry fired. Does this resistor change the resistance reading I should expect when testing it at the screws? The water in the heater is cold.

My top resistored element is reading about 450k ohms and the bottom non-resistored element is reading what I would normally expect at about 14 ohms. They are both 4500 watts with 240V supply. If I should expect the resistored one to read the same as a non resistored then it's obviously bad, but I can't find online what these resistored element should read resistance wise. TIA.

driveguy
  • 103
  • 2

1 Answers1

3

Not "resistored" but "fused". The Rheem product literature for that model says that the upper element is thermally fused to prevent damage from dry firing.

e

A thermal fuse does not change the resistance reading of the element at all until the fuse opens due to excessive temperature; then it reads infinite resistance -- though in the real world maybe 450Kohms is close enough to infinity to be the equivalent.

You should look for a thermal fuse associated with the upper element, since it's inexpensive and replaceable. If you don't know what to look for, you can take a photo and add it to your question.

MTA
  • 15,038
  • 1
  • 22
  • 53