Hot Water questions

[mdo23]

On my electric hot water heater the reset on the top thermostat keeps constantly tripping. After it cools down, i am able to reset it. While it is reset and working, the only element that I see getting power is the top element, the bottom element never has any power on it, any ideas on what oculd be wrong?

[LazyPup]

This is a two part question so let us answer the second part first.

"While it is reset and working, the only element that I see getting power is the top element,"

Although your water heater has two elements it only uses one at at time. The top thermotat is a single pole double throw switch that provides an either/or switching action When the top element is energized the bottom element is off and when the top thermostat is satisfied it turns the top element off and sends power to the bottom thermostat which then senses the temperture of the tank at the bottom to determine if it should switch on.

The RESET button is actually a separate device that is mounted on a common mount and mated with the upper thermostat.

The reset button is a manual reset Thermodisc overload protector that will trip off either by excessive heat or excessive current draw.

Begin by turning the circuit breaker off or pull the service disconnect switch for the water heater and use a meter to confirm the power is off.

Then check the spring mount for the upper thermostat. If that mount is bent and the thermostat is even slightly loose allowing a gap between the back of the thermostat and the tank wall the tank will overheat and trip the reset.

Visually check all wire connections to make sure there are no loose connections or burnt ends on the wires. Loose connections or burnt ends would increase the resistance and the reset would then trip out on current overload.

Disconnect one wire from the upper element and use an ohm meter to measure the resistance between the two terminals of the heating element. If the resistance is 8 to 15ohms it should be okay. If the ohm meter shows zero ohms of resistance the element is shorted out and must be replaced. If it shows infinite resistance the element is burned out and will need replacing.

once you have measure the resistance on one element replace the wire you removed then go to the other element, remove one wire and repeat the test as above.

[cjn1972]

I am having the exact same problem on mine, and have not tried what you suggested as of yet. Was wondering if you check that out and all appears fine, or you find no problems and the issue continues to occur, would the next step be to replace the upper thermostat?

[zrfarrar]

Originally Posted by LazyPup

This is a two part question so let us answer the second part first.

"While it is reset and working, the only element that I see getting power is the top element,"

Although your water heater has two elements it only uses one at at time. The top thermotat is a single pole double throw switch that provides an either/or switching action When the top element is energized the bottom element is off and when the top thermostat is satisfied it turns the top element off and sends power to the bottom thermostat which then senses the temperture of the tank at the bottom to determine if it should switch on.

The RESET button is actually a separate device that is mounted on a common mount and mated with the upper thermostat.

The reset button is a manual reset Thermodisc overload protector that will trip off either by excessive heat or excessive current draw.

Begin by turning the circuit breaker off or pull the service disconnect switch for the water heater and use a meter to confirm the power is off.

Then check the spring mount for the upper thermostat. If that mount is bent and the thermostat is even slightly loose allowing a gap between the back of the thermostat and the tank wall the tank will overheat and trip the reset.

Visually check all wire connections to make sure there are no loose connections or burnt ends on the wires. Loose connections or burnt ends would increase the resistance and the reset would then trip out on current overload.

Disconnect one wire from the upper element and use an ohm meter to measure the resistance between the two terminals of the heating element. If the resistance is 8 to 15ohms it should be okay. If the ohm meter shows zero ohms of resistance the element is shorted out and must be replaced. If it shows infinite resistance the element is burned out and will need replacing.

once you have measure the resistance on one element replace the wire you removed then go to the other element, remove one wire and repeat the test as above.

I have been troubleshooting a water heater problem for a couple of days now (turned out to be a combination of deposits and a dead heating element). After changing out the dead heater, I have been scratching my head about whether or not the thermostats were working properly - I would see 240v at the top and zero at the bottom. I wasn't watching long enough... Lol. Thanks!