Hot water heater reset keeps tripping

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Old 04-06-20, 04:24 PM
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Hot water heater reset keeps tripping

Hello,

I have an eight-year-old electric hot water heater, and it has been tripping the reset frequently over the past ~4-5 months. Currently, this is happening once or twice a day, and seems to correlate with us doing activities that use hot water, like operating the dishwasher. I'm not certain of the capacity of the unit, which was already here when we purchased our house, but it is larger than others typically found in houses.

Since the water heater began resetting, I have replaced the elements twice and have replaced both the upper and lower thermostats. But this does not help the problem. The water heats up quickly, and becomes overheated relative to the settings on the thermostat. At some point, the reset is tripped, and we typically do not have hot water in the morning.

Yesterday, I replaced the elements for the second time. I noticed that when I drained the heater, the water that came out first, from the bottom, was cold, whereas the water that came out last was steaming hot.

I don't know very much about hot water heaters, and I don't have any ideas about what could still be going wrong. Maybe someone here has some suggestions about what could still be going wrong for me.

Thanks for your help,
garlic
 
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Old 04-06-20, 05:37 PM
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it has been tripping the reset frequently over the past ~4-5 months.
The reset you speak of is a high temperature limit switch so the unit is definitely overheating. My experience is that after the limit has tripped 3 or 4 times it is pretty well shot. Since you have replaced the thermostats the limit has been replaced too as it is an integral part of an upper thermostat. One key is that the thermostats be mounted so they have direct contact with the tank or they cannot properly sense the temperature. Another key is proper wiring. Replacing elements will have no bearing on your problem. The best water heater thermostats are marked T O D for Therm-O-Disc from Emerson Electric. I would advise not setting the thermostats over 125-130 degrees max.
 
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Old 04-06-20, 06:28 PM
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Thanks for the reply, CasualJoe.

So, what you are suggesting is that I would have to replace the upper thermostat again, since the current replacement thermostats have been through far more than 3-4 resets? When you suggest that the high temperature limit is shot, do you mean that it may trip, even if the temperature does not exceed the limit that I've set it to?

You also mention that proper wiring is key. We had not had problems with the water heater for the first ~3.5 years that we were in the house. Do you imagine that this could still be the problem, given that it apparently lasted for a long time prior to the initial reset?

Thanks again,
garlic
 
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Old 04-06-20, 08:01 PM
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8 years old. just replace the heater.. IMO your just wasting $$$ on parts.

Call a local plumbing company to come and install. It will keep us guys in business during these trying times..
 
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Old 04-06-20, 10:01 PM
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If it weren't for these trying times, I would be contacting a professional. But I'm not having anyone in my house for the next while...
 
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Old 04-07-20, 03:52 PM
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If you want to troubleshoot the water heater..... you're going to need an ohmmeter. You will need to turn power off to the WH. Remove all four wires from the heating elements. Check from each screw to ground. More that likely one of the elements is going to show continuity. That would be a defective/shorted element.

A shorted element will allow the water heater to keep heating even after the thermostat stops calling. This is usually the reason the high heat stat trips.
 
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Old 04-08-20, 08:36 AM
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PJ brings up an interesting point and yes, it can happen. Many many years ago I worked on a lot of electric water heaters and never ran into a shorted element that overheated a tank, but it could happen. I suppose the water quality could be a factor in what types of problems an electric water heater may have.
A shorted element will allow the water heater to keep heating even after the thermostat stops calling.

8 years old. just replace the heater.. IMO your just wasting $$$ on parts.
Maybe and maybe not. I typically get 20+ years out of a gas water heater, last one was 24 years old when I replaced it because I figured it was due to go out soon. I recall from many years ago a few people who had softeners and an electric heater. Some of those heaters were pretty old and clean as a whistle inside.
 
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Old 04-09-20, 01:57 PM
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Thanks for the suggestion. I do have a multimeter, so I can definitely test this.

A couple of questions, though:

1) the WH continued to trip the reset on the very day that I replaced the elements. Do you think that this decreases the likelihood that the problem is related to a shorted element?
2) Are the elements quite delicate (i.e., might they have been damaged during delivery?).

Sorry for all the questions!
 
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Old 04-09-20, 02:12 PM
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The elements are not delicate and are not likely damaged during shipping or installation.

The water heater wiring is very basic. There are two thermostats. A top one and bottom one. The top one tells the top element to heat. When it reaches set temperature it turns off the top element and tells the bottom element to heat. Then the bottom thermostat controls the bottom element. The thermostats are fairly reliable. I can't remember the last time I saw a shorted (on) thermostat. It can happen but you can test for that. What is harder to test is the shorted element problem.

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