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The Complete Electric Water Heater Repair Guide - Plumb University

The Complete Electric Water Heater Repair Guide

by Trevor Woods | Last Updated: April 12, 2020

Despite being among some of the most vital appliances of your home, a hot water heater is oftentimes taken for granted. You use hot water every single day, and just like any other appliance in your house, hot water heaters require maintenance and repair.

Luckily, tank-type water heaters are quite simple to troubleshoot and work on. There aren’t many components on an electric hot water tank and you can easily replace parts and fix problems yourself!

In this guide, we will show you how to determine if you have an electric hot water heater, discuss how to fix all the common problems that come with electric hot water tanks, and how to diagnose electrical issues.

Let’s start off by going over the differences between an electric and gas-powered water heater.

What Is The Difference Between An Electric And A Gas Hot Water Heater?

When it comes to electric hot water heaters, they look pretty much the same as the gas hot water heaters. Both are essentially large water storage vessels with inlet waterlines supplying the tank with fresh cold water and outlets providing your home with piping hot water.

Both of these heaters contain the insulated storage tank jacket that is typically made of steel. The insulation between the tank jacket and the storage tank prevents heat loss from the water that gets heated.

The main difference between the two water heater styles is their heat source. A gas hot water heater uses a gas burner, which heats up the water from the bottom of the tank. While and electric hot water heater uses electrical elements, one upper and one lower, to warm up your water.

These elements work similarly to light bulbs. Electricity passes through the coil or conductor which provides resistance to the flow of electricity, but instead of this electrical friction converting into light energy, it is transformed into heat.

Flanged or screw-in hot water elements extend into the hot water tank and are submerged in water. Each is controlled by its own thermostat and the two thermostats work together to control the heating of the water inside your tank.

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Upper and lower replacement thermostats for your electric water heater.

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The majority of electrical hot water tank issues are caused by either the elements or thermostats. Problems such as generating water that is too hot, little to no hot water at all, and poor recovery times are all due to these two components.

Important Safety Tips

Before you start diagnosing or trying to fix an issue with your electric hot water heater, make sure that you turn the power off first. Most electric hot water tanks come with a high supply voltage of 240-volts and are extremely dangerous to work with if the power is on.

Prior to checking any electrical components of your water heater, make sure that you turn off the power to the heater’s circuit by switching off the correct breaker in your house’s service panel, also known as the breaker box.

Always double-check using a non-contact voltage detector to test all of the wires in your water heater in order to confirm that the power is completely off before you touch the wires. 

If you are someone who is attempting to repair your electric hot water heater for the very first time then you are going to need a multimeter and a basic understanding of how to use it. Plus, you need to take all of the typical safety precautions when working with electricity.

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Do not open the hot water tank’s access panels when the power is on. Make sure to always check that the power to the water heater is off. Do not trust a circuit breaker label, confirm with a multimeter or voltage tester on the electrical outlet before you inspect the water heater.

Now that we have covered all of the important safety tips, let’s dive into the list of the most common problems that occur with an electric hot water heater. 

Common Electric Hot Water Heater Problems 

There Isn’t Enough Hot Water

If your electric hot water heater is generating hot water, but it isn’t enough, then your hot water tank might be too small to meet the hot water demand of your household.

An electric hot water heater is designed to have 75% of its capacity as hot water. So, for instance, a water heater of 40 gallons is appropriately sized for a demand of 30 gallons.

For easy math, if your showerhead uses 2 gallons per minute (GPM) then you can have a 15-minute shower before the hot water tank starts to run cold. Most electric water heaters have a recovery rate for about an hour before they are full of hot water again.

So if the demand is too high for your heater’s capacity, then try to take shorter showers or installing more water-efficient plumbing fixtures. Low-flow showerheads or properly timing loads in the dishwasher or laundry machine may also help maintain the amount of hot water you have on hand.

If your family has grown or there are more members of your household use a lot more hot water as compared to a couple of years ago, then you should consider getting a newer model water heater that has a larger capacity tank.

You also have the option of installing a point-of-use water heater that is closer to the source of water you use the most, such as the shower. But most homes don’t have the required space to install one of these units.

However, if your usage hasn’t increased or the tank isn’t undersized and the water heater started producing less hot water all of a sudden, then one or even both of the heating elements might have failed.

If during your showers you are constantly getting lukewarm water then that is a sign of a faulty upper heating element. If the hot water runs out a lot quicker than it used to then that is a sign of a faulty lower heating element

There Isn’t Any Hot Water

No hot water is one of the most common and irritating situations you will face with an electric hot water tank. No one likes a cold shower, brrrrr!

If your electric hot water heater isn’t producing any hot water then it might not be getting enough power, a high limit switch there might be tripped, or a heating element has failed.

First, you need to check the circuit breaker of your water heater in the service panel in order to ensure that it has not tripped. If the breaker did end up getting tripped, thanks to an electrical storm for instance, then turn it completely off and then back on again.

However, if the breaker of the heater didn’t trip and it’s still on, then you can try resetting the water heater’s high-temperature limit. This limit reset is a red button found on the hot water tank’s upper thermostat.

Reset The Limit Switch By Following These Steps 

  1. Switch off the breaker of the water heater’s circuit inside the service panel.
  2. Next, take out the access panel of the upper heating element of the water heater.
  3. Also, take out the insulation plus the plastic safety guard. Be careful and don’t touch any of the wires or the electrical terminals.
  4. After that, push the red button, which is the high-temperature cutoff switch. If it has been tripped, you should hear an audible “click” when you press and reset the button.
  5. Next, replace the safety guard, the insulation, and the access panel.
  6. Finally, turn the circuit breaker of the heater back on. 

You should start to notice that your hot water is starting to be restored after 20-30 minutes.

However, if this also doesn’t solve the issue or the reset trips again, you will have to get your multimeter and start testing each thermostat and element to determine why you have no hot water.

The following video provides in-depth instructions on testing your thermostats and elements on your electric hot water tank.

PRO TIP: Since the top thermostat controls the bottom thermostat, the general rule of thumb is if there is no hot water replace inspect the top thermostat and element. And if there is limited hot water, inspect the bottom thermostat and element.

The Temperature Of The Water Is Too Hot

Getting too much hot water is just as frustrating as not getting enough hot water only more dangerous due to the chance of getting scalded. The reason that you are experiencing this problem could be due to one or both of the thermostats on the water heater being set too high. You can take a look at the thermostat settings by following the instructions below:

  1. First, switch the power of the water heater off in the service panel. 
  2. Take off both access panels, the insulations, and the plastic safety guard from each of the heating elements on the water heater. Make sure not to touch any of the wires or the electrical terminals. 
  3. Next, use a non-contact voltage tester and test all the wires in order to make sure that the power is turned off. 
  4. Once you have done that, observe both thermostats and check their heat setting. They need to be showing the same temperature and we recommended a temperature of 120 F. 
  5. Use a flathead screwdriver to adjust and change the temperature to your desired setting. 
  6. Confirm the temperature of the other thermostat and make sure the temperature is set the same on both thermostats. 
  7. Next, reinstall the safety guard, the insulation, and the access panels for each element.
  8. Finally, switch on the circuit breaker of your heater. 

Reduce Your Energy Bill

Save money by turning down your water heater thermostats. For each 10ºF reduction, you could save 3-5% on your electricity consumption.

It Takes A Long Time For The Water To Reheat Again

This can be a disadvantage of having an electric hot water heater. On average, the time required to reheat the entire water supply with an electric heater is twice that of a gas water heater.

The time that’s needed to reheat the water varies greatly depending on the water heater application, wattage of the heating elements, and the available power supply. depending on different heater models. Generally speaking, newer electric heaters are more efficient and recover faster than older models.

However, if it takes a long time for the water in the tank to be reheated again there might be a problem with the heating elements, such as sediment or mineral deposit build-up on them.

The thermostats could also be worn out and not sensing the temperature of the tank correctly. We will show you in the next section how to properly troubleshoot whether it thermostats or elements are the cause of your slower recovery rate.

The Tank Is Making Noises

If your water heater is making noises that sound like a popping noise, a low rumbling, or a high pitched whine, then that is probably the sound of water that’s boiling inside the tank. This is also called “kettling” thanks to sounding similar to a tea kettle boiling a pot of water.

When an electric water heater’s bottom has a lot of sediment build-up, this could result in overheating the lower element in the tank. This element is trying to overcome the resistance from the sediment build-up and heat water to a set temperature.

Small amounts of water trapped in the tank’s mineral deposits are quickly heated and bubble through the sediment as it rises to the top of the tank. The noise this kettling makes is not a sign that the tank is about to “blow” but it is a serious problem.

You need to drain the water heater and flush all the remaining sediment out of the tank. Draining your hot water tank should be done periodically to help increase the efficiency of the water heater and extend it’s working lifespan.

Water Leaking From The Water Heater

Usually, water leaks occur thanks to problematic plumbing connections and valves, but there could also be some tank issues. A home could get significantly damaged due to leaking water heater; hence it is very important that you get this leak fixed as soon as you can.

Water Is Leaking From The Top

If there is a leak towards the top side of your electric hot water heater, then that could be caused by several things. The hot outlet or cold inlet pipes could be loose. Perhaps, the T&P valve might have failed. Or the inlet valve could be leaking. It is best to check all of these components in order to find the one that is causing the water to leak from the top of your tank. 

Water Is Leaking From The Bottom

If your electric hot water heater starts to leak from the bottom that usually happens due to an electric heating element gasket that has failed, excessive condensation, or the T&P valve has opened in order to relieve extra pressure from the tank. If the Temperature and Pressure valve has opened it will allow a small amount of water to be pushed out through the overflow pipe and pool on the floor nearby.

In the case of leaking water around heating elements, you need to inspect them for any looseness and use an element wrench to tighten them, if needed. Replacement gaskets are available if yours is worn or damaged.

If the tank itself is corroded, you cannot repair it and the entire water heater needs to be replaced. You will need to switch off the power and the water supply to your water heater. After that, you need to completely drain the tank in order to stop the leak and before you can replace the water heater.

The Pressure Of The Hot Water Is Low 

Older houses that have half-inch diameter galvanized piping, that supplies the water heater, are usually the ones that complain about the pressure of the hot water being low. The cold supply water pressure entering the tank will equal the pressure of the hot water leaving the water heater.

The ideal solution to this issue is to install modern piping that is ¾ inches and will allow a lot more water to flow through the hot water tank. Changing to less restrictive water heater inlet piping will provide a big boost to your hot water pressure.

Other culprits of limited hot water pressure are calcium-deposits, sediment build-up, or corrosion inside sink aerators, plumbing pipes, or water heater inlets.

The Water Is Rust Colored Or Dirty 

If your hot water is brown or rusty in color, this means either the anode rod or the tank itself is starting to corrode. If you do not fix this issue quickly the corrosion will progress and the hot water tank will start to leak and you will end up having to install a new water heater.

Start by checking to see if your sacrificial anode rod needs to be replaced. The anode rod can easily be changed and replacing it will increase the life of your electric hot water heater.

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On the other hand, if the water is dirty rather than rusty, then this could be due to sediment build-up in the tank that is travelling into the hot water outlet. A simple draining and flushing of your water heater will fix this right away.

The Hot Water Smells Bad

If your hot water smells really bad then this could be due to bacteria in the water heater tank. Homes that use well water usually encounter this issue and their water can give off a bad odor. To temporarily solve the issue, periodic flushing of your electric hot water heater can help.

Another cause for smelly water could be a result of how your water reacts with the water heater’s anode rod. Depending on the quality of your water, you could experience a “rotten egg” smell from a magnesium and aluminum anode rod.

Replacing your anode rod with one made of aluminum and zinc is a cheap solution to combat stinky hot water.

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A better option would be to get a powered anode rod. These provide superior corrosion resistance, improve water quality, are lower maintenance than standard anode rods, and will eliminate hot water odors.

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Electric Water Heater Repairs

What if you are experiencing electric water heater issues that require further troubleshooting? No problem! Diagnosing electric water heaters is quite simple to do with a voltmeter in a few minutes.

Electric hot water tanks are made up of only a few components; thermostats and elements. The following video provides a complete overview of how to properly identify which electric water heater part needs replacement.

Once you have determined the cause for your water heater troubles, we will show you how to replace each piece below.

How To Change A Hot Water Tank Element

A heating element that has burnt out or gone bad is the number one reason why electric water heaters fail to produce hot water. Heating elements can last up to 10 years but their lifespan can be considerably less depending on your water quality, temperature settings, and frequency of use.

When changing a heating element, make sure that you replace it with one that has identical wattage and the same mount and gasket style. This information can typically be found on the water heater’s identification sticker on the side of the tank.

Why Do Elements Go Bad?

Heating elements can start to fail due to a variety of reasons. Mineral deposits in your water can hasten an element‘s demise. Dissolved minerals in your water harden onto the element during the heating process. This solidified coating of minerals insulates the heating element from the water and forces the element to work harder (and decreases its lifespan) to overcome this insulation barrier.

A power surge or sudden change in voltage can be enough to burn out a heating element. A lightning storm or power surge from your utility company can result in a voltage spike higher than what a heating element is rated for, causing it to burn out.

A bad thermostat will allow the element to run longer or more frequently than necessary and reduce its lifespan. Poor wiring connections can decrease the element‘s ability to function properly or stop working altogether.

Dry fire can burn an element out completely in a very short period of time. Heating elements are designed to operate while completely submerged in water. If the element turns on and is not surrounded by water it can quickly heat up past its safe operating temperature and self-destruct in less than a minute!

Tools You’ll Need

How To

1. Power Off

Turn the power to the water heater off at the electrical panel or circuit breaker. The breaker for the hot water tank should be labelled. Hot Water, Water Heater, or HWT are examples of what might be written on the breaker box directory.

2. Open Cover Panel

Next, remove the cover panel and insulation underneath. This will expose the element and thermostat. Also, remove the plastic protective cover. This will allow you to double-check with a voltmeter on non-contact voltage tester that there is no power going to the element.

3. Turn Off The Water

Turn the cold water inlet to the hot water tank off. This valve should be located close to the top of the water heater. Now, open a hot water faucet nearby to relieve system pressure. This release of pressure will allow the water heater to drain.

4. Drain The Tank

Connect a garden hose to the hot water tank drain valve on the bottom of the tank and run the hose to a floor drain or somewhere safely outside. Open the drain valve and empty the tank to a level that is below the element you are replacing. This can take 20-30 minutes depending on the size of the water heater.

5. Disconnect The Element Wires

While the tank is draining, remove the two wires from the element you are replacing. Don’t worry if you can’t remember the which way the wires are installed because it won’t matter when you install the new element. Water heater elements do not have any polarity so either terminal will work just fine for reinstallation.

6. Remove The Old Element

Slowly remove the element by unthreading it with an element socket or removing the flange bolts that secure it to the tank. If water starts leaking out as you loosen the element, you haven’t drained the tank enough.

Pull the element out carefully. Try not to scrape off any excess scale or water deposits while you remove it from the tank. If the element is damaged or broken, be careful to remove the entire element and not to drop any broken pieces of the element inside the tank.

7. Install The New Element

Install the new matching heating element and gasket. Snug up the connection with the element socket or wrench.

8. Turn The Water Back On

Turn the water back on to the water heater and start filling the tank. As the tank fills, the air inside the water heater will exit through the faucet you had opened previously. Once the faucet has finished coughing and sneezing and is flowing normally, go ahead and turn the faucet off again.

Don’t Dry Fire!

Never turn the power on to the electric water heater when it is empty. Without the tank completely full of water you run the risk of dry firing the heating elements and having the elements burn out instantly.

9. Inspect For Leaks

Check the element you replaced for any dribbles and drips around the gasket. Tighten as necessary.

10. Reconnect Element Wires

Then connect the electrical wires to the element and double-check to make sure the terminal connections are snug.

11. Reinstall Cover Panel

Now you can reinstall the white plastic protective plate, insulation, and cover panel.

12. Turn The Power On

Finally, turn the power back on to the electric water heater at the circuit breaker or electric panel. Done!

It will take about 30 minutes before you notice any hot water and about an hour for the tank to be full of hot water and ready to use.

How to Change A Thermostat On A Electric Water Heater

Thermostats on your electric water heater control the heating elements that warm the water inside the hot water tank. These little thermostats are mechanical bi-metal switches that sense temperature through sidewalls of the tank and turn their corresponding elements ON and OFF.

There are typically two thermostats on your water heater. One on the top which controls the upper element and one on the bottom which controls the bottom element. The upper thermostat is the main controller and will send power to the lower thermostat when the top portion of water in the tank reaches its temperature setting.

Then the lower thermostat will turn on the bottom element until the lower thermostat is satisfied. Due to convection, warm water will rise to the top of the tank and the cooler water will settle to the bottom. So during times when hot water is not in use, the lower element will cycle ON and OFF to maintain the tank’s water temperature.

It’s a simple design where both thermostats and elements work together to heat water but never operate at the same time.

While thermostats don’t necessarily have a set lifespan, you can expect them to last much longer than the elements. Ageing, poor wiring connections, and power surges can all impact how long you can expect a thermostat to last. Luckily, thermostats a very easy to change!

Water Heater Thermostat Kit

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Tools You’ll Need

How To

1. Power Off

Turn the power to the water heater off at your home’s electrical panel or circuit breaker. The breaker for the hot water tank should be labelled. Hot Water, Water Heater, or HWT are examples of what might be written on the breaker box directory.

2. Open Cover Panel

Next, remove the cover panel and insulation underneath. This will expose the thermostat and the element it controls. Also, remove the plastic protective cover. This will allow you to double-check with a voltmeter on non-contact voltage tester that there is no power going to the thermostat.

3. Disconnect Thermostat Wires

Mark, tag, or take a photo with your smartphone of the wiring before removing them from the thermostat. This will help with their reinstallation later.

4. Remove The Thermostat

Lift the side clip retaining brackets carefully and slid the old thermostat up and out of position.

5. Install The New Thermostat

Slide the new replacement thermostat under the retaining clips. Make sure the retaining clips are holding the thermostat firmly against the sidewall of the tank.

6. Rewire The New Thermostat

Following your tagged layout or BEFORE picture, reconnect the wiring to the new thermostat and double-check all the wire terminals are snug.

A Typical Wiring Diagram For An Electric Water Heater

7. Adjust The Temperature

Using a flat blade screwdriver set the temperature of the thermostat. Increase the temperature by turning the dial clockwise and decrease the temperature by turning counter-clockwise.

Hot Water Safety

Do not set the temperature on the thermostat above 120 degrees Fahrenheit. Warmer temperatures than 120 degrees Fahrenheit greatly increases your risk of scalding.

8. Reinstall Cover Panel

Now you can reinstall the white plastic protective plate, insulation, and cover panel.

9. Turn The Power On

Finish up by turn the power back on to the electric water heater at the circuit breaker or electric panel. Done!

It will take about 30 minutes before you notice any hot water and about an hour for the tank to be full of hot water and ready to use.

Calling In The Pros

We know that mixing water with electricity can make for an intimidating situation. Repairing an electric water heater is quite safe if you follow basic safety precautions and always ensure that the power is off before you start working on your hot water tank.

Some jobs like replacing circuit breakers in your electrical panel, relocating your electric water heater, or switching from a gas to an electric water heater are best left to professional electricians and plumbers.

Conclusion

A cold shower can be frustrating but fixing your electric water heater doesn’t have to be. Electric hot water tanks are simple appliances that can be easily diagnosed repaired. The next time you run out of hot water, don’t worry, you got this! Fix it yourself and you’ll be relaxing in a warm bubble bath before you know it!

Happy Plumbing!

Trevor Woods is the founder of Plumb University® and he started in the plumbing and construction industry in 1997. Since then, his mission is to make plumbing repair and maintenance easy for everyone. And each year, he continues to help more people with their plumbing installation, care, and troubleshooting.