Water Heater not working, Can't figure out what is wrong.

[Gregj107]

I have two Bradford White 50 gallon water heaters in line to provide 100 gallons of hot water. This morning one of the heaters stopped working. The Water heater is getting 238 volts. I checked the upper and lower elements and got an ohm reading on the upper element at 13.4 ohms, the bottom element was 18 ohms. I then took the thermostat from the water heater that does not work and put it in the water heater that does work. The water heater that works still worked when I put in the thermostat from the water heater that does not work.

I then decided to install a new upper element and the heater still did not work. I can't figure out what is wrong with the water heater, The thermostat is ok and installing a new element did not help. Wiring looks fine. Any suggestions?

Thank you

Greg

 

[Reach4]

The Water heater is getting 238 volts. I checked the upper and lower elements and got an ohm reading on the upper element at 13.4 ohms, the bottom element was 18 ohms.

Do you get 238 volts across the two terminals for the upper element? I suspect you took your voltage reading somewhere else.

 

[Sponsor]

 

[Gregj107]

I disconnected the Red and Black wire at the top of the thermostat on the upper element to take the reading. The reading actually varies from 236 to 238 volt. I also just hooked up the water heater to the other electrical for the water heater that is working and it still does not work.

 

[Reach4]

Try leaving the wires attached to the top element, and reading the voltage across the element. I expect something is stopping the current.

How could this happen? Suppose, for example, there was a high-resistance connection on one of the hots. Let's say 100 kohm for example. You would still read about 240 across the two hots, because the current is near zero. If you power the element, the voltage in that case would be much lower.

If you found that to be the case, you could measure each hot to ground, and tell which path had the high-resistance.

The high resistance could even be in the breaker.

 

[WorthFlorida]

Though most of the wiring inside the WH can be seen, time to measure the ohms from the upper thermostat to the elements. Since the tank is probably cold, power will only be switched to the upper element. With power on you'll read 240 between L1 and L3 and between T2 and L4. If not at T2&T4, push in the red reset button. Reading 240 at the upper element doesn't mean the element is good, it could be open but since to have replaced the elements, nix that. If you are not reading power at the element, check the wires (blue and yellow). You can put the voltmeter on one wire and the other to the tank itself (Ground). You'll read 120v's. If not then there is an open wire from the thermostat.

 

[WorthFlorida]

I made one omission, you need to disconnect the wires at the upper element to check voltage. As I originally wrote it, if one wire is open you'll read voltage on both sides of the element since power will travel through the element. For a voltmeter only a few micro amps are needed.