Dear Mr. Electrician: I woke up today to find my electric water heater not working. How do I repair my electric water heater?
Answer: When you find an electric water heater not working there are several steps to take to find the root cause and make repairs to the electric water heater. NOTE: Some text links below go to applicable products on Amazon.
If you see water dripping from the water heater tank, it is time for a full water heater replacement. Tanks cannot be repaired, only replaced. When you do replace the water heater, I recommend that a pan be installed under it to prevent future flooding. An electric water heater should have a plastic pan while a gas or oil fired water heater should have a metal pan under it.
Several things could cause the electric water heater to stop working. A tripped or bad circuit breaker, or even a loose electrical connection will prevent the electric water heater from operating. A disconnect switch at the water heater location could be off or gone bad. The controls on the water heater itself could have tripped to the off position or gone bad. And lastly one or more of the electric heating elements in the water heater could have burned out.
All of these symptoms are easy to check and test for however it means working with live electricity. If you lack experience working around live electrical circuits, I suggest calling in a professional electrician.
The sequence of operation of a standard residential electric water heater with a tank is as follows: With a tank full of cold water the upper heating element turns on first. When the water temperature rises to the level that satisfies the upper thermostat the upper heating element will shut off and power will then go down to the lower heating element thermostat.
The upper thermostat has a built-in double throw switch that goes forth and back between upper and lower heating elements according to upper water temperature.
The lower heating element will stay on until the temperature reaches the lower thermostat setting and then will shut off.
When you turn on the hot water faucet in your home, hot water comes from the top of the tank, travels the pipes and flows out the spout or shower head. When that happens cold water enters the bottom of the tank and lowers the water temperature there.
The lower heating element will heat that water until the water in the upper part of the tank starts to cool. At that point the upper heating element will come on and the lower heating element will go off.
The lower heating element tends to die sooner than the upper element. With only the upper heating element working you would still get hot water, but the stored hot water in the tank would get used up much faster than with both elements operating as designed. If the upper element dies then the lower element will not be able to turn on.
Regular draining of the tank according to the manufacturer’s instructions can help the heating elements operate most efficiently and last longer.
The upper and lower heating elements are identical, but the upper and lower thermostats are not.
The upper thermostat has a reset button which trips off and kills power to both heating elements when the temperature gets too hot. The lower thermostat only regulates the temperature for the lower heating element.
ELECTRIC WATER HEATER NOT WORKING TROUBLE SHOOTING STEPS
My first step would be to check for 240 volt power using my Wiggy voltage tester. I would do this at the built-in junction box at the top of the water heater where the electrical power enters. Remove the cover and pull out the spliced electrical connections. Remove the wire connectors and check for voltage between the two hot wires.
ELECTRIC WATER HEATER NOT WORKING WITH POWER ON
If you have 240 volt power at the water heater junction box, then the problem of the electric water heater not working could very likely be internal. The covers on the side of the water heater would need to be removed so that voltage can be checked at the controls.
However before I check for voltage at the control and element terminals, I would push the red reset button located in the upper compartment behind the cover. If there is a block of insulation or a protective plastic cover there after the outer metal cover is removed, just pull it out and save it for reinstallation.
Resetting the red thermal overload button may be all that is needed to get the water heater working again. However the question remains why did the thermal overload trip off? These normally trip off when the temperature is too hot. Maybe the thermostat is bad or is the temperature set very high?
With the power on and the reset button pushed, use a voltage tester or Cat III volt ohm meter to check the voltage at each heating element screw terminals. Only one heating element should be on at a time unless the water temperature is hot enough to shut off both thermostats.
In that case take a hot shower, or do a load of laundry with hot water to bring cold water into the tank which will turn on one heating element and then the other. Check for voltage at the upper heating element first. When that shuts off check the voltage at the lower element.
If you get voltage at each heating element in the proper sequence, the problem may be a bad heating element. If you don’t get voltage at each element, the problem could be a bad thermostat.
I had a unique experience wiring a client’s brand new electric water heater. I wired the water heater and flipped on the circuit breaker to get the water hot and make sure it was working properly. It was not
Shortly after turning on the power for the first time on the water heater the breaker tripped off. I got out my Amprobe Ammeter and put it on one of the wires connected to the water heater circuit breaker inside of the electrical panel. The water heater was drawing double the current (Amps) that it should have been.
During my investigation the thermal overload on the upper heating element also tripped off which meant the water was getting too hot.
The short story is that the upper thermostat module was bad and was causing both heating elements to operate at the same time. Normally only one heating element is on at any time.
I contacted the factory and they shipped a new free replacement thermostat module, but to get my client going immediately I went to a big store and bought a generic electric water heater thermostat which fit perfectly on the water heater.
Replacing a water heater thermostat is not difficult. First thing is to take a picture of the electrical connections before taking anything apart. Then loosen the screw terminals and pull the wires out from each screw terminal. Rather than move the wires completely out of the way, I prefer to leave them as they are originally positioned as much as possible to make it easier to connect to the new thermostat.
It would be terrific if you could take one wire off the old thermostat at a time before removal and put it on the new thermostat before it is installed. However wires are not always long enough to that.
Here’s a short video demonstrating water heater thermostat removal:
It is not necessary to drain an electric water heater tank to replace the thermostats. The tank only needs to be drained when replacing the heating elements.
Use a Cat III volt ohm meter to test the heating elements before attempting to remove them. Shut off power to the water heater at the circuit breaker. Confirm that the power is off with a voltage tester. Disconnect the two wires on the heating element.
Set your volt ohm meter to measure resistance at the lowest scale (R1) and connect one probe to one screw terminal on one of the heating elements and the other volt ohm meter probe to the other screw. Write down the measurement. Now check the other heating element the same way and write down that reading.
Normally both measurements would be nearly identical. If they are not, one element is going bad.
A 240 volt, 1500 watt water heater heating element should measure around 38 ohms, a 2000 watt element should be 28-29 ohms, a 2500 watt element should be 23 ohms, a 3000 watt element should be around 19 ohms, a 3,500 watt element should register around 16 ohms, a 4,500 watt element should read between 12 and 13 ohms, and a 5,500 watt element should register between 10 and 11 ohms.
Next attach one of the meter probes onto the metal jacket of the water heater or hold it to the metal tank. Use the other probe to touch each screw terminal on both heating elements. Write down those measurements.
Also use the other probe to test the metal hex nut of the heating elements and write down the measurements.
If your meter indicates any measurements at all no matter how small when testing to the metal tank that means that the element(s) needs to be replaced.
To replace a heating element first turn off the power going to the water heater. Check to make sure power is off at the water heater using a voltage tester. Connect a garden hose to the drain valve. With the water to the heater still on, open the drain valve at the bottom of the tank briefly to flush out any sediment. Do this a few times until no more sediment is observed coming out of the hose.
Next turn off the water going to the water heater. Open up the drain valve again and let all of the tank pressure out. Turn on a hot water faucet in the kitchen or bathroom or both after the pressure is down. Draining will take a long time, but can be speeded up by opening the temperature pressure relief valve (TPR) on the side of the water heater. That will allow more air to come in. Just lift the handle on the TPR to let air in.
I know some plumbers use an air compressor to pump higher air pressure into the tank to force the water out faster. You could also remove the lower heating element to drain the tank, but this will be very messy and cause a flood if you cannot direct the water somewhere such as the pan beneath it that has a drain pipe connected to it.
I have also seen some people remove the drain valve completely to let the water flow out faster. You just need a way to contain or direct the 30 – 80 gallons of water that will come out otherwise you will have a flood.
Sometimes there is so much sediment at the bottom of the tank that the drain valve gets clogged. Pushing a piece of wire through the drain valve may clear it. Otherwise removal of the drain valve or the lower heating element is the most viable option for draining the tank.
One problem that may arise from opening the drain valve is that the drain valve may not close completely again and will drip. You can put a cap on it or change the valve to a better quality unit. I like a brass valve better than a plastic valve.
I used a 3/4″ breaker bar with an 1 1/2″ 6 point hex socket to remove this heating element. This is not the best tool for removing heating elements. The breaker bar does give me great leverage, but due to the beveled or chamfered inside edges of the socket and lack of depth on the heating element I had to force the socket to stay in place while trying to turn it. Amazon sells heating element wrenches.
The water heater tank must be full of water BEFORE TURNING ON THE POWER. Turn on the water valve for the water heater and turn on one hot water faucet in your home to let the air out of the tank and water pipes. Close the TPR valve.
The tank must be completely full before you turn the power back on otherwise the heating elements will burn up immediately from not being surrounded by water.
Wait until air no longer comes out of any faucets before turning on the power to the water heater.
IF THERE IS NO POWER AT THE WATER HEATER
If no voltage is present at the water heater junction box I would go to the electrical panel and check the voltage coming off of the circuit breaker. If the voltage readings are not correct at the circuit breaker, I would tighten the screw terminals on the breaker and try measuring the voltage again. If there isn’t 240 volts at the circuit breaker, I would remove it and check the voltage at the circuit breaker panel main terminals and the bus bars.
Look at the underside of the circuit breaker to see if there are any burning or arcing indications. Even if there is no obvious signs that the breaker is bad, it still could be bad.
If the circuit breaker was in the tripped position when you initially inspected it, try resetting it by pushing the handle all the way to the OFF position and then push it to the ON position. If the circuit breaker trips again, there is an electrical problem somewhere that needs to be found.
Disconnect the electric water heater at the water heater junction box and cap the bare ends of the wires separately on the electrical cable supplying power to the water heater. Then go and reset the circuit breaker again to see what happens.
If the circuit breaker is able to reset, with the water heater disconnected, then the problem is inside the water heater.
If the circuit breaker trips again with the water heater disconnected, then the problem is somewhere in the circuit supplying power to the electric water heater. This could be difficult to locate as often the wiring is inside walls.
Did the shut down of the water heater coincide with any work being done around the house? Did someone hang a painting on a wall and inadvertently drive a nail through the water heater circuit wiring?
Of course the electrical wiring could be very old and the insulation on the wires could have broken down to create the short circuit that is causing the circuit breaker to trip. In that case new circuit wiring needs to be installed.
If the circuit breaker trips again after resetting, but only after a short duration then it is possible that one of the heating elements has broken down to the point where it is leaking electricity into the water in the tank. The resistance of the water in the tank delays the tripping of the circuit breaker because it limits the current flow. Replacement of the defective heating element will correct this.
If you have 240 volts at the main electrical panel terminals and bus bars, but not from the water heater circuit breaker then it is likely that the circuit breaker is bad and should be replaced. See the chart below for the correct circuit breaker rating for your electric water heater. Also confirm that the correct wire size is installed for your water heater.
Depending on where your electric water heater is located such as a basement or garage, the electrical circuit for it may be required to have GFCI protection. This requirement is explained in article 210.8(A) of the National Electrical Code.
If you only have power on one of the bus bars or main terminals in the main electrical panel then you have a bigger electrical problem. In this instance other things in your home may not have electricity. Check to see if any other 240 volt appliances turn on such as a stove or air conditioner.
A power failure on one of the main electrical terminals can be caused by a bad main circuit breaker or loose connections on the main breaker, problems at the electric meter, a problem at the weather head where the power company connects to your house. It could also be caused by a problem at the power company transformer.
If you find that one half of your main electrical panel is without electricity I suggest that you call the power company first to have them take a look. You could call an electrician first, but the power company won’t charge you for a service call and if the problem is with their equipment the electrician could not fix it anyway.
If you find that after getting your water heater working again the hot water temperature fades down too soon during your long showers, turn up the temperature a little on the lower heating element thermostat only.
In your home the metal hot water pipe and the metal cold water pipe are required to be electrically bonded together. This is accomplished with a short piece of #8 or #6 copper wire and two water pipe ground clamps. Notice the green wire in the photo at the top of this page.
Although the National Electrical Code does not specify where the bonding connection is to be installed, it does require it to be accessible. Consequently the bonding connection is usually made at the water heater because it is accessible and it does have the hot and cold water pipes attached. It is also easy for the inspector to find. The water heater itself is not approved to be used as the bonding connection.
ELECTRIC WATER HEATER TROUBLESHOOTING TOOLS
The tools that I use for troubleshooting an electric water heater that is not working are as follows:
MANUFACTURERS TO CONTACT WHEN YOU FIND YOUR ELECTRIC WATER HEATER NOT WORKING
Links to other appliance related blog posts on my site can be seen here.