Hot Water Heater

[diablo]

I have a few questions about an electric hot water heater. It's a 40 gallon electric model with an upper and lower thermostat. It sits in the basement and the facets that it's connected to haven't been used in a few years. I wasn't getting any hot water when I turned the hot side of the faucet on, so I took the inspection covers off the hot water heater. I pressed the reset button and it pulled in and I can hear the unit working now.

The question I have is should I get 220 volts across the lower heating element and lower thermostat when I check both screw terminals? I get 120 volts when I touch one and one side of the meter to ground. But when I check both terminals I get nothing.

The upper thermostats and element read 220 volts when the meter is placed on the pair of screws at the same time. Is the lower working right?

Thanks, Brian

[Ook]

Only one heater element comes on at any given time. The top will come on first, and not until it heats up and shuts off will it send power to the bottom element. So, turn it on, you should have 220-240v across the top element, nothing across the bottom element. Let it run a bit. After a short period of time, the top of the tank will be hot, the upper thermostat shuts off the upper element, and sends power to the bottom element. You will no longer have anything across the top element, and you will have 220-240 across the bottom element. When the rest of the tank warms up, bottom element shuts off, the entire tank is up to temperature.

The reason for this is for the top element to come on and quickly heat the top of the tank. That way you get hot water quickly without having to wait for the entire tank to heat up. I once did not understand this and thought something was wrong with the thremostat, so I wired both elements to the top thermostat. Fortunately, the breaker in the breaker panel quickly popped before I burned the house down :(. I figured it out real fast.

[diablo]

Your 100% correct, when I went back to it after I posted my question, the top element had went to zero volts and the bottom was reading 220 volts.

Thanks for the help.

Brian

[Jeff Wisnia]

And you would also have gotten 120 volts if you touched the OTHER end of that element, because the thermostats in most electric water heaters are single pole switches. The upper thermostat disconnected one side of the

220 volt line, but the other side was still connected to the lower element.

Jeff

[Stormin Mormon]

Typically, the upper thermostat has a sequencer. So that one element is powered, or the other. But not both at the same time. Sounds like the lower element is hot enough, and so it's heating on the top element. Since you can turn off an element by breaking one leg of the 220, it's very possible to read 120 volts to ground.

Quite possible that your WH is just fine. What's the complaint?

[diablo]

Other than I was not getting any hot water, found the internal breaker in the heater and reset it, nothing.

Then as inquiring minds want to know, is everything working correctly? That was the reason for the questions, I obviously didn't understand how the thermostats worked.

Ook and Jeff then explained to me that it's working correctly.

Brian

[mm]

The red button near the wh element is not a breaker. It's a heat limit switch. Although it does break the ciruit, it does so on the basis of high temp, not high current. Using the term breaker will confuse people.

[diablo]

What is it's purpose? To break when the water is over temperature?

Brian