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Water heater thermostat evidence of failure (C) Daniel FriedmanElectric Hot Water Heater Repair FAQs 5
Q&A on How to fix an electric water heater, cylinder, geyser, calorifier

Electric water heater diagnosis & repair questions & answers - set#5:

FAQs on how to test and repair an electric hot water heater that is not heating at all or is not producing enough hot water.

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Q&A on How to Repair an Electric Water Heater / Calorifier / Geyser

Electric water heater thermostat and electrode access panels (C) Daniel Friedman

These questions & answers were posted originally at ELECTRIC WATER HEATER REPAIR GUIDE - home - be sure to review that article.

On 2019-11-07 by (mod) - electric water heater goes BANG and trips breaker

Dave you are describing what sounds to me like a dangerous short circuit.

Watch out: Leave electrical power to the heater OFF right now as what you describe could be dangerous.

Then you can call a repair person.

IT is possible that the short circuit is caused by a burnt-out and shorted heater element - that's repairable - or similarly a control on the water heater. So you may not need a whole new unit.

Let me know what the service tech finds and we can comment further.

On 2019-11-07 by dave

my electric water heater makes abang sound and pops the breaker can it be fixed or do i have to replace

On 2019-10-26 by (mod) -

JJ

Normally a breaker trips in response to over-current, to protect against a fire; so

either

- the heater has an internal short or failure in its wiring or in one of its controls - most likely

or

- the breaker or wiring to the heater are defective; what is the brand of electrical panel and breaker (attach a photo or two, one per comment, of the panel, breaker, and of the water heater brand/logo and its data tag) and

is there aluminum electrical wiring in the home at the panel or at the water heater?

On 2019-10-25 by jjwjup

My new water heater makes hot water , but trips the breaker after 5 - 10 minutes . I reset the breaker , same thing . Check the sink , warm to hot water . I tested both heating elements , they are fine . Can anyone give me an idea what the problem is ?

On 2019-09-11 by (mod) -

I'd test the element itself as described in this article series; if the element's ok and the wiring is correct then I'd test the thermostat: see if it delivers power to the element.

Watch out: if you're not trained on electrical testing you could be shocked or killed.

On 2019-09-10 by Ervin

I have a 55 gal A O Smith water heater with dual elements. I have replaced both of the elements and I replaced the top and bottom thermostats. For some reason I can not get the bottom element to heat up. The top is working and I have checked to make sure everything was wired up correctly

On 2019-08-06 by (mod) -

OK so we have a short circuit somewhere in your wiring, controls, or water heater. Start by checking the wiring itself for shorts to ground or shorts hot to neutral.

Watch out: if you aren't trained on safe electrical troubleshooting you could be shocked or killed.

On 2019-08-05 by Link

Replaced breaker at box, both heating elements and thermostats and still kicks breaker.

On 2019-05-16 by (mod) -

Interesting anonymous question

1. Check the VOM on another source or wire in each function and mode to be sure it's not a problem with the meter, batteries, probes, or internals

2. Then look for a loose connection on the water heater circuit or component being tested

3. If you're testing an element the element itself could be corroded and failing but also shorting - watch out don't get killed - be safe or give up

On 2019-05-16 by Anonymous

Why is myΩ meter going crazy on the waterheater

On 2019-04-28 by (mod) -

JG

The good news, if there is such, is that electric water heaters are pretty simple without many parts to diagnose and replace.

When there is an intermittent TOO HOT problem I certainly suspect a bad thermostat at the water heater; keep in mind that when you replace some thermostats you're also replacing the temperature sensor integral with the control, but as I explained below for David, others use a physically separate temperature probe.

If your heater uses a separate probe that device could be defective.

IF not then I'd be looking for a loose wire.
'
Watch out: making a mistake in inspecting or fooling with electric wiring can shock or kill you.

On 2019-04-28 18:42:34.028472 by Jgamilgho@yahoo.com

Hi, i have an electric AO Smith water heater that is 6 years old - recently the water started getting too hot and then the water turns cold - i reset the upper thermostat and it kept happening again - i bought/installed a new upper thermostat and it kept again - water gets super hot then the thermostat has to be reset - any idea what is going on? Thanks a lot

On 2019-02-01 18:27:00.070992 by (mod) -

David

For most water heaters the thermostat (unlike the actual electric heating elements themselves) can be replaced without draining the heater - as many if not most use a temperature sensor that relies on tank contact.

Watch out: however there are some water heater thermostats that do use an internal temperature sensor that is immersed in the heater's water: to replace one of those the heater has to be drained. I illustrate one of these below.

To replace a more-conventional electric water heater thermostat you'll still need to turn off power, confirm that it's off at the heater, and let the heater cool off to a safe temperature before working on it.

Tip: Take a photo of the wiring connections before removing them, that way you can be sure you're replacing the connections in their original position.
IMAGE LOST by older version of Clark Van Oyen’s useful Comments code - now fixed. Please re-post the image if you can. Sorry. Mod.

On 2019-02-01 by (mod) - immersion type water heater thermostat

David

For most water heaters the thermostat (unlike the actual electric heating elements themselves) can be replaced without draining the heater - as many if not most use a temperature sensor that relies on tank contact.

Watch out: however there are some water heater thermostats that do use an internal temperature sensor that is immersed in the heater's water: to replace one of those the heater has to be drained. I illustrate one of these below.

To replace a more-conventional electric water heater thermostat you'll still need to turn off power, confirm that it's off at the heater, and let the heater cool off to a safe temperature before working on it.

Tip: Take a photo of the wiring connections before removing them, that way you can be sure you're replacing the connections in their original position.

On 2019-02-01 by david burt

to replace thermostat does water need to be drained

On 2019-01-23 by Nova

Changed electrodes in hot water tank last night. It worked last night but no hot water this morning. How do I fix?

On 2018-12-22 by (mod) - shorted electrical wires can dim lights or worse

No Margie,

A power surge is a sudden increase in voltage delivered from the electrical power company.

Watch out: However a dead short on any electrical appliance including an electric water heater could cause a momentary light flicker as the fuse or circuit breaker blows or trips.

That could happen if someone were installing an electric water heater and if they shorted wires - they also could have been killed, shocked, or started a fire.

On 2018-12-22 by margie l howard

can replacing a heating cause power surge through the house

On 2018-11-13 by (mod) -

Mona

That sounds as if there is a shorted lower element or a defective thermostat.

On 2018-11-13 by Mona

Have a 40 gal electric water heater that keeps tripping the reset button. I have changed thr top thermostat and it still continues.

On 2018-11-07 by (mod) -

Interesting. I suspect it's fine - just a lower-priced model using only a single element. Certainly it's the case that there are single-element water heaters, and if in a tall heater the plan was to install only a single element, it would need to be in the lower position near the heater bottom.

On 2018-11-07 by Andrew

I have a electric hot water heater and the space for the top element seems to have never been used since it came from the factory. It's a 30 gal unit and is heating fine with the bottom element being replaced. The top element/thermostat doesn't ever appear to be used. I'm wondering if this is normal in some heaters.

On 2018-11-04 by (mod) - Does my water heater need to b drained every year?

Pat

Indeed some manufacturers recommend and you will or periodic flushing of the water heater.

You've asked a great question.

In nearly 50 years of working on this topic I've never come across a homeowner or other maintenance person who actually follow that advice.

In this article series you will find whoever a detailed procedure for flushing the water heater. It's something that people are often moved to do when they hear the heater rumbling and being very noisy and they need to de-scale it.

On 2018-11-04 by Pat

Does my water heater need to b drained yrly ?

On 2019-02-12 by (mod) -

Rog

Is it a 2-element heater?

Ususally the problem is the upper heater got burned up - e.g. if power was turned on while the element was in air rather than under water in the heater.

Do a resistance check on the element.

On 2019-02-12 by Roger Busch

Electric water heater only produces warm water, set up thermostats did not help. Replaced both elements.

On 2019-01-22 by (mod) - burning plastic odor

Zach,

The burning plastic sounds as if there was a short circuit or wiring error.

Let's start with the most common snafu: IF you turned power on to the heater before it was absolutely full of water and contained NO air, that will burn up the heater element in a jiffy.

On 2019-01-21 by Zach

About 2 weeks ago I replaced the elements on my 50 gal Electric Water Heater. Later that night I smelt burning plastic and found the lower thermostat had started to melt. I ran to lowes and purchased the upper/lower thermostat kit. I replaced the bottom one.

A few days later the water heater started to trip the breaker box once or twice a day and now it is constant. I also replaced the upper thermostat but we are seeing the same results. Please note that when I changed the elements I saw that the tank was at least 1/3 full or more of calcium and I tried my best to clear it up.

Would the issues we see stem from the lower element getting too hot too quick because of the calcium build up and not enough water surrounding it?

2nd part of this question is it worth trying to remove the calcium from the DIY tricks i have read (vinegar or CLR) and let it sit for a few hours before draining the tank?

Or is it time to replace the unit? I live in Indiana where the water is hard...hard enough that it killed our dishwasher.

Thank you.

On 2019-01-04 by (mod) -

for safety it sounds to me like you need to turn the water heater off. I'm very nervous that water around electrical contacts could shock or kill someone. There's no point in replacing the elements if the heater is leaking.

On 2019-01-04 by Josh

I have little bit of water in the electric boxes of electric water heater along with rusty elements I can see by just looking in...we have no water should I go ahead and replace the elements or the whole water heater? Plz help

On 2018-09-15 by (mod) -

when the water heater is producing hot water, as you find at its outlet, but you are not getting hot water at a downstream fixture, I suspect that there is a problem with heat loss and root or even inadvertent mixing of cold with the hot at your faucet.

On 2018-09-12 by willie williams

I replace upper &lower thermostats &elements. hot water pipe hot and lavatory hot side warm . I have never experience this please help.

On 2018-02-20 03:52:56.839761 by (mod) -

Not much. I'd test them

On 2018-02-19 21:42:23.163714 by Foolish homeowner

Hey i drained my cabin electric hot water heater dry without cutting the power off. Tank dry about 30 minutes before i realized i forgot to cut power. Any chance i did not burn the elements out ?

On 2018-01-28 by (mod) -

Kevin

I'm left only guessing that when you turned the water back "on" the valve is not actually opening to let water flow.
Or you've left another main water supply valve off.

On 2018-01-27 by Kevin

Have a water heater everything seems to be working fine had a leak under the house turn water off then turn the water back on so that I could find the leak but now no hot water will come out at all out of the hole that’s leaking or out of any Spicket’s can someone please help me


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