27 replies to this topic

[randtm]

I've got an 80 gal. Kenmore water heater model 153.321841. It's about 8 years old now. It heats water great, but it's always, and I mean always, liked to trip its high limit breaker. Since the unit was new, it has tripped it about 2-3 times a year. I reset it, and it's fine for a few more months usually until it does it again. Here's some more details - it's always the top thermostat limit that trips. Both the upper and lower thermostats are firmly seated against the tank. Both the upper and lower thermostats have been replaced over the life of the unit, and the lower heating element and top thermostat were just replaced about 6 months ago. I thought that might finally end this, but it didn't. There's not much to these things other than two thermostats and two heating elements with some wiring between them, so it just doesn't seem that complex. I'm stumped as to why this keeps happening. Is this common with this model and these thermostats, is there a simple fix, or do I just have a flaky unit with a mysterious problem? This has gotten really frustrating. Thanks for any help.

[jumptrout]

What size wire to the unit?
What size breaker in circuit panel?
Is ground wire firmly attached?
Are power outages or brownouts happening?
Has lower stat been replaced?
Is this a dedicated power circuit?
What is amp draw on the heater when heating?

[randtm]

Good questions. I'll answer most of them tonight. In the meantime...

10 ga. wire, but I'll double check
I'll check breaker size
Unit is grounded but I'll double check connection
Don't believe related to power outages or brownouts, but not sure, it does usually seem to happen overnight. Water is usually extremely hot in the morning and cold by night when this happens.
Lower stat has been replaced once a couple or more years ago.
Yes, dedicated circuit
I'll check the specs for the amp draw.

Thanks again.

[randtm]

Okay, here are the answers -

10 ga. wire - NM-B 2 length of run is only about 25-30 feet to load center
Breaker is 30 amp
Ground screws are all tight
No evidence of outages or brownouts that I know of.
Lower stat was replaced once a couple or more years ago. I replaced upper stat and lower element last Sept. - Oct. when the unit wouldn't heat at all and my multi-meter tested both the thermostat as bad, and showed the lower element was shorting to ground. Original element was convertible from 3800 watts to 5500, which was done, but new element is strictly 5500. Behavior of occasional tripping the upper high limit breaker though has been the same both before and after this stat - element replacement episode. Upper stat was also replaced several years ago, but I don't remember when.
Yes, dedicated circuit
The unit is rated 3800 watts for the top element and 5500 watts for the lower. At 220 volts, that's 25 amps by my calculation.
Double checked that both stats are firmly seated against tank.

Definitely would like to find a solution to this. Unit has now tripped three days in a row, which is completely new. As I said, it has always only done it once every few months prior to this.

[RegUS_PatOff]

... always, liked to trip its high limit breaker.

... I'm not too familiar with electric water heaters,
but are we talking about a thermal limit ?
If so, it may be tripping if there's air in the system (instead of water) at the High-Limit thermostat.
Do you have a standard High-Pressure Relief Valve ?
Does it work ?
It may be clogged.
(have you tried it) ?

[randtm]

Well, I suppose we're talking about a thermal limit. I'm talking about the little red button in the middle of each thermostat on the unit the pops out and turns off current if the heater "runs away" and heats the water too hot. The circuit breaker in the breaker box has never tripped for the unit, just the temp limit on the thermostat, and as I said, always the upper one, which of course, cuts power to both elements.

I did go check the pressure relief valve. Gave me a bunch of hot water with no air, so seemed normal.

Thanks for the suggestion. I'm open to any ideas.

[jumptrout]

This reset button activates on a short circuit or a power(amp) overload.
The stat itself can have a weak button and trip.
The stat may be sticking and not cycle off at the set temp causing the bi-metal to trip from heating up due to extended current flow..
Remove the wires and check for continuity from the wires to the tank and the element terminals to the tank and the wires to the ground wire.
Run new temporary wires from the upper to lower stat.
What temp are the stats set for?

[randtm]

We have small children, so stats are set fairly low. Each one is about halfway between the "A" and the "B". I get about 125-130 degrees with a candy thermometer at the kitchen sink.

I'll try the continuity tests tonight. I know I mentioned having a multi-meter, but I don't want to give the false impression that I know too much about what I'm doing, more "just enough to be dangerous". While I could probably follow all the checks you mentioned above, if you could provide any more detail on exactly which checks I should make, i'd be more comfortable that I'm checking the right things. I've attached the wiring diagram for the unit out of the manual, if that helps. Also, I have spare 12 ga. wire around. Is that sufficient, e.g. safe, to use between the two stats or do I need some 10 ga.? Thanks.

Attached Files

•  water_heater_wiring.jpg   58.88K   21 downloads

[RegUS_PatOff]

This reset button activates on a short circuit or a power(amp) overload.

I don't think so ...
see page 2
http://eet.canton.ed...er%20heater.pdf

from another installation instructions:
Upper and lower thermostats must be adjusted to the same temperature.

[randtm]

Okay, I wasn't able to do everything tonight due to lack of time and needing to deal with kids, but I did manage to do some of the meter checks. From what I would assume, they seem normal. No continuity from the element terminals to the tank. Continuity from the wires to the grounding screw. One thing that is and has bugged me big time in the past about this thing though, is that the wiring in the unit does not match the wiring diagram in the manual. I'm guessing they knew what they were doing at the factory, but maybe this is related afterall. Looking at the wiring diagram, the red wire coming down from the electrical connections at the top of the tank should go directly to a terminal on the lower element. It doesn't. It goes to the top of the bottom thermostat. The black wire off the bottom of the top thermostat should go to the top of the bottom thermostat and it doesn't. It goes directly to the lower element. I'm guessing this is acceptable. I do still get 120 volts on the lower element at all times when measured between the element screw and the ground wire when the lower element is not operating, as I understand it should be. I'm just surprised the unit wiring doesn't match the diagram. I know that is was not miswired when installed because the wire lengths are such that they couldn't be connected any other way, so it came from the factory this way. Could this be related to the problem, or is it a red herring?

[RegUS_PatOff]

... the wiring in the unit does not match the wiring diagram in the manual

maybe the Installers wired it wrong ?
Did you replace (wire) the replacement Thermostats ?
wiring pictures ?

[jumptrout]

I don't think so ...
see page 2
http://eet.canton.ed...er%20heater.pdf

from another installation instructions:
Upper and lower thermostats must be adjusted to the same temperature.

Why doesn't this site have a brain fart emoticon?

[randtm]

I was the installer. I know for a fact it is wired exactly as from the factory. As I said, the wire lengths are such that it can only be wired a single way. Plus, at initial installation, only the connections at the top of the unit had to be made. Perhaps I should call customer support and verify the writing diagram. Maybe it did come wired incorrectly and I need to rewire it correctly.

[RegUS_PatOff]

wiring pictures ?

[Bullstok]

It does not matter what 120 leg goes to the stat and what one goes to the element first. You need 220 to complete the circuit and 220 is a combination of both legs. All that really matters is that the upper stat is wired correctly so it sends 220v to only one element at a time. If the ECO is sometimes tripping then usually one of the stats is sometimes sticking or the ECO is shot. Usually there is not a ECO on the lower stat unless someone installed the wrong stat. If the ECO on the upper stat trips it doesn't necessarily mean the upper stat is bad. It means the water at the top of the tank is too hot (hot water rises) or the ECO is weak. If it trips many times it is probably weak because its not meant to be reset over and over like that, but regardless, the lower stat can be responsible for the upper ECO tripping. Also make sure the elements are the correct wattage for the voltage your heater is using. They have different ratings marked on them for other voltages. Check that your amp draw is correct and that all connections are tight, especially near the ECO. It senses heat. If the wires are loose or drawing too many amps through the ECO it could be adding heat to the ECO internally and causing problems.

Edited by Bullstok, 22 March 2012 - 07:27 PM.

[randtm]

Okay, here are wiring pictures of the top and bottom stat. You will notice that the red wire (labeled black in wiring diagram) goes from the bottom of the top stat, to one terminal of the element. A black wire, coming down from the top of the unit and bypassing the top stat entirely, goes to the top of the bottom stat. Yes, I understand and agree that is should not matter which 120 leg goes where, but do find it curious that the unit doesn't match the wiring diagram. You can also see that as I said, it is impossible that it wasn't this way from the factory as that black wire coming from the top of the unit is obviously going nowhere but to the top of the bottom stat.

I also agree that an ECO is not technically necessary on the bottom stat, but I can assure you and you can check the parts list on the Sears PartsDirect site and you will see that this unit is supposed to indeed have an ECO on the bottom stat, and it always has, though the bottom stat has been replaced once, and the top one twice.

I'll also point out that a "weak" ECO is not the issue. The water heater is RUNNING AWAY! The water is scaulding hot when it does this, so it is not the ECO tripping when it shouldn't. I believe it is the bottom element heating until the top ECO trips and not being properly cut off at termperature by the lower thermostat. I just don't understand why it has done this, intermittently, since we've had the unit, and even more so, why it is continuously doing it this week.

For lack of anything else, short of replacing the whole thing, which I'm not up to yet, I ordered a new top and bottom stat for the unit that will be here tomorrow. Maybe that will at least calm it down for the time being. I'm just not optimistic that it won't start doing the same again in a few months and I just don't get it. It's quite a mystery that I'm fed up with, since as I mentioned, there's not much to these things. The only thing that hasn't been replaced in it is the top element. Maybe it should be...

 water_heater_upper_stat.JPG   108.65K   20 downloads  water_heater_lower_stat.JPG   143.57K   16 downloads

[Bullstok]

Btw: Your diagram shows only 1 ECO. Your heater has 2. Please show a pic of the junction at the top of the heater. It looks sort of like 3 power wires go to the supply junction instead of the normal 2. I could be seeing it wrong or they could be tied together up top. Hopefully the third wire isn't tied to a neutral or something wierd like a three phase setup

Update: I found your manual online. That is the wrong diagram you posted. There is another for "three wire" that you need on the next part of the page. It matches your setup perfectly. It talks of "off peak" meters and such. Do you use one of those setups? That will change things drastically as off peaks are complicated to wire and the bottom element is then controlled by the power utility typically by radio signal. If not then the black and blue should be tied together up top on one incoming supply leg, and the yellow on the other supply leg.


 Untitled.jpg   121.87K   10 downloads

Edited by Bullstok, 22 March 2012 - 10:01 PM.

[randtm]

Ahh interesting... I never paid any attention to that "three wire" diagram because, no, I don't have any off peak meters or such and only have a two wire supply line. But, I do agree with you that the unit is pre-wired to work with such now that I notice it and is wired based upon that second diagram. Good to see that the wiring in the unit does match the wiring diagram afterall. Also, that explains the ECO on the lower stat, which is shown in that diagram, but not in the first one. But I digress slightly...

Attached is a picture of the wiring junction at the top of the unit, which confirms the unit is wired correctly based upon the three wire diagram, following the part about, "if you only have a two wire supply, connect the black and blue wires to one leg, and the yellow wire to the other."...

So, with posting all these pictures serving as a double check that everything is wired correctly and does match the manual, we're left with the ever perplexing question of... WHAT GIVES WITH THIS THING???

Still hoping someone has some ideas... I'm all out, other than throwing yet another set of stats in it.

Should anyone ask, the bottom element was replaced, as I mentioned, on Sept.-Oct. last year and is solely 5500 watts. The top element is the factory original at 3800 watts. Maybe I shouldn't have done the 5500 watt lower element. Maybe it says it can handle it, but really isn't up to it afterall. Don't really want to replace more elements at this point though. A bit of a pain...

 water_heater_top_wiring.JPG   179.94K   11 downloads

[Bullstok]

Rarely, If there is a lot of crap, build up, or old element parts left in the bottom of the tank partially grounding the element, it can heat off of the 120 volts that are always present wether or not it has 220v from the stat, without tripping the circuit breaker. Turn off power. Unhook the element wires. Check element terminals for resistance to ground. Check this on both elements. Also you have never posted actual tested amp readings. You really need a clamp on style electrical meter to be working on electric water heaters as you can see amp draw on either leg of either element or total loads.

Oops, you already checked to ground. Sorry, missed that before, getting too late for me. Although you should check for any resistance, not just continuity. Continuity to ground should trip the circuit breaker. A higher resistance might not and could heat water. The thing is if it only overheats every so often, resistance might not show up when you test. Pulling the elements to check for build up and/or flushing the tank could help. Although you have passed out of water heaters 101 by a ways... Intermittant problems sure sux.

Edited by Bullstok, 22 March 2012 - 11:36 PM.

[randtm]

Intermittant problems sure sux.

Uh, yeah, tell me about it! So, I'm a bit skeptical that buildup is causing any of my issues. As I said, it's done this even within the first few months when it was new. When the unit went out late last year, it picked a particularly bad time as I discovered it late on a Sunday and I was leaving Monday morning for a week-long business trip. I did some quick meter troubleshooting and decided it appeared the lower element and upper stat seemed to be both having issues, but since that was only about $60 worth of parts, I didn't go to much effort to isolate it further. I started the tank draining and ran out at 7:30 that Monday morning, got the parts, threw them in, and was on the road for my trip by 11:00am, happy that I got it done so quickly and avoided a service call or replacing it. Anyway, when I pulled the lower element, it was clean as a whistle, with no visible signs of any issues. I was skeptical that it really had a problem, but it was testing with my meter as shorting to ground, so I figured best to replace it. I wasn't thrilled with the upper stat I got from my local shop at the time as it was not "original equipment" but a universal stat that "should be okay for that unit". I've also flushed the unit periodically and never got much out of it. We do have an acid neutralizer with iron removal and a water softener, so there isn't much crap in our water that goes into it.

Anyway, I'll put the new stats in it and while I'm pretty optimistic that will settle it down for now, I fully expect it to start this again within a few months. I also found a detailed list of meter readings to do when troubleshooting a water heater elsewhere on the web and I think I'll go through all those and see if anything interesting shows up. I'll post it if it does. If the unit acts up again in a few months, I think at that point I'll just replace both the top and bottom elements and put a 3800 watt element in the lower. I'm still wondering if the 5500 watt element isn't somehow at the root of all this. Of course, the one constant in all of this is the top element which is the only thing that hasn't ever been replaced, so I wonder about it too.

Of course, at least in one way, I have gotten my original question answered. I was originally wondering if this was a common known problem with these units/thermostats that had a known fix and the answer to that appears to be no.

I would like to try to get the amp readings, but that one's new to me. Can you give me an idea of exactly how I measure those?

UPDATE: Okay, I googled taking amp readings and I think that one's probably beyond my capabilities with my meter. I have a cheapie meter my wife gave me as a stocking stuffer that was probably $10 from Radio Shack. If I understand the procedure correctly, flowing 25 amps through the leads of this meter sounds like an unwise (e.g. foolish) endevour. Not sure the investment in something that could handle it is warranted.

Thanks.

Edited by randtm, 23 March 2012 - 09:57 AM.