After replacing the elements in our tank, googled re: testing the old elements to see which had died. Wish I’d done the google search before I replaced them – ahh well, candies and nuts. I’m tacking this info by the HW heater for future reference:
From www.plumbingstore.com:
View Image “How do I check an electric water heater element? Should the elements be removed to check it, and do I need to drain the tank?”
View Image It isn’t necessary to remove the elements or drain the tank to test them, but the elements must be removed (and the tank drained) to replace them. To test the elements, you will need a voltage/OHM meter. Turn off the power to the heater first and disconnect the two wires to the elements. Set the meter to the “OHM” function, and check the flow between the two screw connectors of the elements: If there is a positive reading, then the circuit is “closed” and the element is fine; if there is no reading, the circuit is “open” and a new element is needed. Also, if you get a reading on your meter between either of the screw connections and the metal element, the element is shorted and must be replaced. You should expect an approximation of the following readings on the OHM meter (give or take a little) for functioning elements:
- 15.5 ohms for 3500 watts
- 13.0 ohms for 4500 watts
- 10.0 ohms for 5500 watts
Replies
Or, ya can just remember that V^2/R =watts, 240^2 (in your head) is 57600
A little harder head calci is 57600/3500W = 576/35 or 60/3.5 minus some or about 16 1/2 or so ohms
Oh ####, my brain is dead, does not agree with a published figure....WTF ........
Resistance increases with temperature, so the units will have a hair more resistance when operating than when you test them cold. For practical purposes, and given the inaccuracies of many ohmmeters and the additional contact resistance you often encounter with the test probes, any reading between about 10 and 20 ohms indicates a good element. A defective unit is unlikely to read lower than several hundred ohms.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
TCR for nichrome is close to zero.