View Full Version : Thermostats

white tiger
12-17-2008, 07:42 AM
What is the best way to tell if thermostats are bad in electric water heater? I checked elements and shows 12-13 ohms. I also replaced top thermostat but when I turned water heater back on I could not hear any sound of element starting to heat up water. How should I check the bottom thermostat? Thanks! Dale:confused:

WV Hillbilly
12-17-2008, 08:33 AM
I am not familiar with the test meter you said you were using but make sure it is set on
ACV . With the breaker on touch the meter leads to the two screws on the end of the top element that has the wires under them . You should have 220/240 volts reading on your meter . If you do & the heater isn't heating the element is bad . If you don't have voltage there try the same thing on the bottom element . If no voltage at either element you have a bad thermostat , bad connection where the wire from the panel connects to the heater wires at the top of the heater or no voltage coming from the breaker . Another way to test the elements is to turn off the breaker , loosen the screws on the end of the element , remove the wires from under the screws & take an ohm reading on the element screws with the wires removed . You should get a good ohm reading through the element . If you don't the element is bad . After doing this you should also touch 1 meter lead to one of the element screws & the other meter lead to the metal tank . Repeat using the other screw & tank . You should not get an ohm reading between either screw & the tank . You can't get a correct ohm reading through the elements with the wires attached . In my experience 90 % of the time when a heater quits heating the top element is bad although of course there's always that 10 % .

WV Hillbilly
12-17-2008, 08:54 AM
Three ways to tell if the heater is heating . 1 listen for noise from the heater 2 using a meter take an amp reading on the element wire or if each apartment has its own electric meter , the meter to the apartment you're working on will be spinning pretty fast .

12-18-2008, 01:32 PM
Since the thermostat are hardly ever the problem, you may have waster your money. There is a definite protocol for testing heaters, but in general if you have any hot water the upper thermostat and element should be okay. But you have to test ALL four components, both thermostats and both elements to determine the actual problem.