Electric water heater question

pbm

Joined
Apr 19, 2004
Messages
10,292
Location
New York
Last March, before returning north, we had a new 38 gallon water heater installed in our Florida condo.
The old one was still working but was 17 years old and most of our neighbors had changed theirs out already.
Being on the 2nd level we didn't want it to spring a leak down on our neighbor below.
When we got down here a month ago I turned on the electric to the water heater as I had always done in the past and I do remember some sounds that I hadn't remembered hearing before. We had hot water so I didn't think there was a problem. The other evening my wife went to take a bath (rather than her usual shower) and we realized the water wasn't as hot as it used to be with the old water heater (which could be very hot while filling the tub).

Here's what I'm thinking after looking at the heater's owners manual (which states "do not turn on the electric unless the tank is completely full of water".) In the past I would shut off the water before leaving to go north and my House Watch man wouldn't run any water during the entire time we were gone. My new HW man insists on running water which involves shutting the supply on and off. I'm wondering if my tank was half empty when I turned on the electric which burned out my upper heating element (which means that only the lower element is heating the tank) ....explaining the tepidness of the water currently? Are these heating elements that fragile that this one mistake could burn it out? I see a YT video explaining how to test the elements with a multi-meter (which I don't have with me but can probably borrow from a friend). At any rate the new elements aren't very expensive if that's the issue but I was wondering what more knowledgeable guys think.

PS; I already raised the T-stat temp a few degrees as suggested in the OM with no improvement to speak of.
 
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If you study how the two thermostats work (cycle), it seems that if you left the water heater running overnight, it would eventually heat the entire capacity to the lower thermostat setting, even with the top element broken. I'm guessing that the bath tub filling followed prior hot water use (dishes?) and the water heater could not keep up.

I, too, think you are on the right track. Be careful with that electricity!
 
Did you do maintenance on it?
Once in a while, it has to be drained so all the crudz can come out.
The anode rod also needs to be changed every so often.
If not, then the crudz may have build up and causing it not to heat.
 
Replacing a heating element is generally easy.

However before you do, it's a good idea to do a bit of troubleshooting.
 
I suspect you're on the right track. The upper element is likely compromised. The long recovery time and low temp rise are key indicators.

- turn power to the unit off and check element resistance and shorts. If you believe the lower element is good, that's a good "known" value to use. They run in parallel, so make sure to disconnect each element prior to testing. Replace any bad element (not hard to do; plenty of YT videos). Reconnect all leads but leave power off.
- once elements are confirmed good, then fill heater all the way up (you should be able to bleed air out with the T/P valve, and then burp the rest out via a close faucet
- once all air is confirmed out, turn power back on and let it "cycle" for an hour
- test by taking a shower and see if it's "OK"
 
When you turned the faucet to hot initially did air purge? Is the faucet your guy used lower than the heater? Also, what’s the actual temperature? An easy way to check is to hold cheap thermometer under the running water; I like to actually use a very small cup to get an easier reading.

My thermostat seemed to be pretty accurate at the 125F marking (actual temp was 127F), but the next lower marking is 90F and I had to choose right around the mid point to get 122F.

The pipes for my heater also all run up into the overhead from the tank. It‘s also hard to create I siphon if everything to the tank is shut and only one faucet is opened.

Finally, even if one element is out I would think that the other would eventually pick up the slack. I’ve tried this with my heater, which has a set point for each element (two adjustments). When only one was turned down the actual water temperature did not change.

//

Do NOT do any of the following unless you have experience or training with electricity. 220V isn’t something anyone should simply YouTube and troubleshoot on the fly. I also don’t have a ton of experience with newer electric heaters, so I may be wrong about accessibility of what follows.

Open the heater breaker. Open the access panel and check that there is ZERO voltage before moving forward.

The first thing I’d check are the element resistances and then that they’re getting power. You may not know what right should look like, but if the multimeter reads OL (overload = open circuit = element is kaput) or something wildly different than the other one then that would be a good start.

If nothing appears to be wrong visually or with resistance checks then shut the breaker if it’s safe to do so and carefully probe the terminal points upstream of the controller to see if there is voltage. With the thermostat set higher than the tank temperature there will also be voltage at elements.
 
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HM could have left on a hot and cold faucet after shutting off supply and siphoned from the tank depending on the location of everything. That might have burned out the top element. But if he did it properly-supply on first, off last, unlikely to cause harm. It's actually good to keep some water in your drain traps in the sinks and tubs to keep sewer gas out. A low water level burns out the top element, and sediment in the tank burns out the bottom one. And when you turn on an electric WH there will be some noise as the water heats up, especially from cold. And maybe the top element just burnt out, the way new stuff is made nowadays.
 
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