Electric water heater gurus?

[K5Jimmy]

Ive got a 3yo Rheem 40gal I use for the guest bath. It makes hot water, just not much of it. I have 12.8ohm at the top element, 12.3ohm at the lower. 245v upper, o.5v lower. With power off and element wires off, I get 0.2ohm upper 1 to 3, 0 ohm 2 to 4 and 1 to 4. I get 0 ohm 4 to lower tstat. Neither element shows ground. I was gonna change the upper tstat since it controls the lower, but I can only get the lower to come to 243v if I turn the upper to off. I'm now thinking the call limit on the lower tstat is bad. Actually, other than knowing the elements test good and I have 0 ohm across the tstats, I've looked at it enough that I have once again blinded myself. I've tried the call and cut limits with warm water, not cold, not hot.

Feel free to join in with questions, comments, snide remarks and random stories about your water heater adventures or other unrelated but entertaining trivia.

 

[K5wrench]

Some of them are non-simulteneous.
That is; only one element is on at a time.
2- 4,500 watt elements
But only one can be on at a time.

A simulteneous heater would have two seperate 240 volt circuits powering it from seperate double breakers.
2-4,500 watt elements
9,000 watts when both are on.

This helps recovery time tremendously but first hour gallons not so much.
To increase that, you could add capacity by installing a second electric water heater usually in series with the first.

One of our cabins is plumbed this way;
2 electric water heaters in series (the first heater supplies the second heater).
This gives more first hour gallon capacity even though each heater is a non-simulteneous (4,500 watt) dual element 30 gallon heater.


If you have only one double breaker and 2 power wires and a ground, chances are you have a non-simulteneous heater.
Or a simulteneous heater that is wired incorrectly.

A 40 gallon electric non-simulteneous heater will be good for a 10 minute shower.
Electric water heaters suck.

The reasons they are used are usually;
Cheaper installation.
No flue pipe needed.
No gas supply needed.
They come in compact shapes and sizes.
In remote locations where there is no natural gas line or propane is expensive or impossible to get delivered, electricity comes continuously by wire.. that is an advantage for some.

Compared to electric,
Gas water heaters have;
Higher first hour capacity.
High recovery rates.
Longer maintenance intervals.
Perhaps cheaper due to energy prices in some locales.


Other possibilities for your problem could be;
mineralized heating elements.
A cross connection somewhere or a shower valve pressure balance system malfunction.
Inside modern shower valves is a piston between the hot and cold supplies in the brass guts of the valve.
Depending on the design, it is possible to have a malfunction of this pressure balance piston that allows hot water to be restricted or even a cross connection between hot and cold.
It is rare.
But i have seen it with Home Depot bought Pegasus brand shower valves.

I'd start by measuring the temperature of the hot water coming out of the bath faucet.

 

[K5Jimmy]

Some of them are non-simulteneous.
That is; only one element is on at a time.
2- 4,500 watt elements
But only one can be on at a time.

A simulteneous heater would have two seperate 240 volt circuits powering it from seperate double breakers.
2-4,500 watt elements
9,000 watts when both are on.

This helps recovery time tremendously but first hour gallons not so much.
To increase that, you could add capacity by installing a second electric water heater usually in series with the first.

One of our cabins is plumbed this way;
2 electric water heaters in series (the first heater supplies the second heater).
This gives more first hour gallon capacity even though each heater is a non-simulteneous (4,500 watt) dual element 30 gallon heater.


If you have only one double breaker and 2 power wires and a ground, chances are you have a non-simulteneous heater.
Or a simulteneous heater that is wired incorrectly.

A 40 gallon electric non-simulteneous heater will be good for a 10 minute shower.
Electric water heaters suck.

The reasons they are used are usually;
Cheaper installation.
No flue pipe needed.
No gas supply needed.
They come in compact shapes and sizes.

Compared to electric,
Gas water heaters have;
Higher first hour capacity.
High recovery rates.
Longer maintenance intervals.
Perhaps cheaper due to energy prices in some locales.


Other possibilities for your problem could be;
mineralized heating elements.
A cross connection somewhere or a shower valve pressure balance system malfunction.

It's nonsimultaneous, 3 years old, all of a sudden it doesn't put out like it did (kinda like after you marry your girlfriend). I've got a 50gal that works well for the master, kitchen and laundry, so I turn the 40gal off when we don't have company. It only serves the guest full bath and the 1/2 bath sink.

 

[K5wrench]

A

It's nonsimultaneous, 3 years old, all of a sudden it doesn't put out like it did (kinda like after you marry your girlfriend). I've got a 50gal that works well for the master, kitchen and laundry, so I turn the 40gal off when we don't have company. It only serves the guest full bath and the 1/2 bath sink.

A sudden change.
Well.
Make sure the circuit breaker button is pushed in all the way on that t-stat.
Wiring Connections are tight.
Sure sounds like a heating element problem.
That is the most likely thing to go wrong.
But you measured them.
And they both tested nearly the same.
I guess you are back to the t-stat malfunctioning.

Oooo!
Don't turn it off.
Takes forever for a 4,500 watt element to heat 40 gallons.
Do you turn it on a day in advance.. or a few hours?

 

[K5Jimmy]

A

A sudden change.
Well.
Make sure the circuit breaker button is pushed in all the way on that t-stat.
Wiring Connections are tight.
Sure sounds like a heating element problem.
That is the most likely thing to go wrong.
But you measured them.
And they both tested nearly the same.
I guess you are back to the t-stat malfunctioning.

Oooo!
Don't turn it off.
Takes forever for a 4,500 watt element to heat 40 gallons.
Do you turn it on a day in advance.. or a few hours?

Usually the day before. I thought I could save money by shutting down that wing of the house. (2br, 1 1/2 bath)

 

[rampage]

My electric water heater at my cabin kept tripping the breaker after a few seconds of resetting it. Granted it is a 40 year old tank that was only used a few months out of the year. Thought it finally bought the farm. I tried diagnosing it and figured it was one of the elements shorting out. When I went to the hardware store that’s 45 mins away I saw a rebuild kit that included the upper and lower elements and also the upper and lower thermostats for $45. Decided to just buy that since I didn’t want to make another trip to town if it wasn’t the elements that were bad. Good thing I did get the rebuild kit because when I replaced both elements it still tripped the breaker. Replaced both t-stats and it’s been working good as new for over 2 years now, although the sacrificial anode is completely gone but that’s on my to do list. Anyways, I’d just replace everything since it’s not that expensive or hard to do. Why replace one thing only to have something else wear out in the not too distant future?

https://www.homedepot.com/p/Rheem-PROTECH-Tune-Up-Kit-for-Electric-Water-Heaters-SP20060/205651503?cm_mmc=Shopping|G|Base|All-Products|All|All|PLA|71700000014585962|58700001236285396|92700010802552409&gclsrc=aw.ds&&gclid=EAIaIQobChMI1YW43_264QIVGx-tBh1TOAAnEAQYAiABEgK2QfD_BwE

And a word of advice, before you drain the tank make sure you loosen the elements first. Mine were frozen and I had to use a 3 ft pipe on my breaker bar. The tank kept trying to move so I had to refill it with water to give it some weight. Yours isn’t old so you might not have that problem.

 

[rampage]

@K5Jimmy
Fix it yet?

 

[K5Jimmy]

@K5Jimmy
Fix it yet?

Not yet, we had company all week. Thinking I'm just gonna swap out both thermostats and see what that gets me before I drain the tank to change out the elements.