Trouble With Electric Hot Water Heater

2504 Views 8 Replies 6 Participants Last post by whitedavidp, Apr 22, 2009

whitedavidp

Discussion Starter · Apr 2, 2009

Hot sure to place this in Appliances, Plumbing, or Electrical (or somewhere else). So here goes. Pardon any duplication or confusion...

Have had my electric hot water heater now for several years. Of recent I have noticed that while there is hot water, there isn't alot and it isn't that hot.

I believe this started after I turned off the water to our house while we were away for an extended period. Before I did this I turned-off the circuit breakers to the water heater as I was sure having it on might cause problems. I did not drain the tank but I did leave all the faucets on it the house. When we returned, I turned on the water, closed all the faucets, and reapplied power to the heater (in that order).

This is a typical 60 gallon heater with 2 elements. I am assuming that one element is shot. But how to test this theory? Also could it have been caused by my turning off water to the house?

Thanks.

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brokenknee

· #2 · Apr 3, 2009

Shut off electricity to water heater, take off the plates that cover the heating elements, (double check to make sure power is off) disconnect wires from heating elements, use ohm meter to check for continuity. If you have continuity they are good, if not they are bad. There is an ohm rating they should fall in, but usually it's a go no go type of deal.

Turning off the water to your house should not matter as long as you turned the breaker off to your water heater.

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micromind

· #3 · Apr 3, 2009 (Edited)

It's possible that the dip tube has broken off and fallen inside the tank.

Here's how a dip tube works; both connections (cold in and hot out) are at the top of the tank. If there is no dip tube, the cold water will go into the tank, and run over to the hot outlet. Very little of the hot water stored in the tank will go out the hot outlet.

If there is a tube installed inside the tank that forces the cold water to the bottom of the tank, only hot water will come out of the hot outlet. Until the cold water level rises to the top, if that much is used.

An easy way to test for a broken dip tube is to open the drain valve at the bottom of the tank. Hot water should come out, but not for more than a few minutes. The reason is because the dip tube forces cold water to the bottom of the tank. If you get lots of hot water (like 50 gallons or so) out of the bottom of the tank, it's because the dip tube is not there, and the cold water is slowly migrating to the bottom.

To test for sure, shut the power and water off to the tank. Remove the cold water inlet pipe, right down to the fitting on top of the tank. The dip tube is a plastic pipe about 4 or 5 feet long with the top end flared out, so it rests just inside the inlet fitting.

If it isn't there, measure the height of the tank, and get a new one. The lower end of it can be anywhere from 2" to 10" from the bottom of the tank. The old broken one will sit harmlessly inside the tank.

Then again, it could also be one of the elements.

Rob

P.S. The elements will usually measure about 10-15 ohms. To test, only one wire needs to be disconnected from each element. Make sure the power is off.

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kenmac

· #4 · Apr 3, 2009

While I wouldn't rule it out.. I haven't seen any bad dip tubes on elec. water heaters.. Most likely element

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AllanJ

· #5 · Apr 3, 2009 (Edited)

whitedavidp said:
I believe this started after I turned off the water to our house while we were away for an extended period. Before I did this I turned-off the circuit breakers to the water heater as I was sure having it on might cause problems. I did not drain the tank but I did leave all the faucets on it the house. When we returned, I turned on the water, closed all the faucets, and reapplied power to the heater (in that order)..

Was water gushing from hot water faucets before you turned on the power? If not you may have blown an element.

If you turned off the water but left some faucets open, lots of water could be drained or siphoned from the tank.

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kennzz05

· #6 · Apr 4, 2009

AllanJ said:
Was water gushing from hot water faucets before you turned on the power? If not you may have blown an element.

If you turned off the water but left some faucets open, lots of water could be drained or siphoned from the tank.

if the tank wasnt drained and power was applied before the upper element was covered with water than he would have no hot water due to a bad upper elem. as the upper has to satisfy to turn on the lower elem

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brokenknee

· #7 · Apr 4, 2009 (Edited)

kennzz05 said:
if the tank wasnt drained and power was applied before the upper element was covered with water than he would have no hot water due to a bad upper elem. as the upper has to satisfy to turn on the lower elem

I believe this is true only for water heaters built prior to 1996. After that it will default to the lower unit.

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whitedavidp

Discussion Starter · #8 · Apr 6, 2009

Updates

Thanks to all who have responded. Your ideas have been quite helpful. I managed to get my ohm meter working and have performed the electrical checks. I fully expected that one of the elements would be bad even though this is a fairly new water heater (2-3 years). But both elements have conductivity and neither indicate continuity to ground. I did note, however, that the upper thermostat was set on the marked line at 125 degrees but the lower one was set lower at maybe 95 degrees. I did not do this myself so maybe it came that way from the factory. Or maybe a renter did this and never told me. Is this a correct way to set these things? I turned the lower element up to 125 on the marked line. I know that this is how the heater is set in our other home.

If the temperature setting is not the real issue, then it seems like the dip tube or the thermostats are the next thing to check out. How likely are these to be an issue with such a new AO Smith unit?

Thanks

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whitedavidp

Discussion Starter · #9 · Apr 22, 2009

micromind said:
It's possible that the dip tube has broken off and fallen inside the tank.

An easy way to test for a broken dip tube is to open the drain valve at the bottom of the tank. Hot water should come out, but not for more than a few minutes. The reason is because the dip tube forces cold water to the bottom of the tank. If you get lots of hot water (like 50 gallons or so) out of the bottom of the tank, it's because the dip tube is not there, and the cold water is slowly migrating to the bottom.

Thanks for this Rob. I did the check at the drain valve (wanted to see if there was any sediment anyway - there wasn't) and found exactly the behavior you said to expect. So the dip tube would seem ok.

After raising the temp setting on the lower element from about 95 to 125 (same as the upper), my results seem much better.

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