Do-it-yourself electric water heater repair. Step by step guides with pics. Tools you'll need, troubleshooting guide and safety advice.
Understanding how an electric water heater works is important for solving electric hot water heater problems. When you understand what a part should do and when, solving the problem will be easy.
How electric water heaters work
Cold water enters the bottom of the tank through a fill tube inside the tank. Hot water is drawn off of the top of the tank through the hot water line.
On a duel element residential water heater, both elements do not heat at the same time.
Starting with a tank of cold water, the upper thermostat will energize the upper element. When the water in the top half of the tank is hot the upper thermostat will shut the power off of the upper element and send it to the lower thermostat and element.
Starting with a tank of hot water. When hot water is used, cold water enters the bottom of the tank at the same time. This will cool the lower thermostat and the lower element will heat.
If enough hot water is used to cool the upper thermostat the lower element will shut down and the upper element will heat. When the upper thermostat is satisfied it will send the power back to the lower thermostat/element.
Taking the information above, let us say that you have a normal amount of hot water but when you use a lot, it takes a long time to heat back up. The likely problem would be the upper thermostat/element.
Suppose you have hot water but its depleted quickly. The problem would most likely be with the lower element/thermostat.This electric water heater troubleshooting guide covers other problems you may have with your water heater.
Water heater power safety
Important - Never trust a label on a breaker box, many times they are
Duel element water heaters should be wired into a double breaker. Best practice is to shut off all double breakers in the box and tag/lock the box before doing any repair work.
You should not remove access panels on a water heater unless the power is off.
Never touch a wire until the power is checked with a multimeter. I have found water heaters wired on two different single pole breakers (very dangerous).
Related pages Tips on how to use a multimeter are here.
Electric water heater repair tips to check water heater power.
Electric water heater repair tools you may need
Water heater reset button/limit switch
The reset button/limit switch is located just above the upper thermostat.
The limit switch/reset button and the upper thermostat are sold as one unit. I separated them in the pic. so you could distinguish between the two.
It is designed to shut off power to the water heater if the water temperature should rise to dangerous levels.
If the limit switch should trip, the reset button will pop out. When the water in the tank has cooled the button can be pushed in to reset the limit switch.
When a limit switch trips, there is a reason. It could be a malfunctioning thermostat, a grounded element or the limit switch itself getting weak.
Learn more about electric water heater repair and the water heater reset button.
Water heater thermostats
Water heater thermostats control the water temperature and act as switching relays, sending power where it needed.
120 volts travels straight through the upper thermostat to both elements.
The elements will always have 120 volts, even with the thermostats off. When a thermostat calls for heat, it will send another 120 volts to the element it controls. This will give the element 240 volts, causing it to heat.
The upper thermostat must be satisfied before the lower thermostat/ element will work.
Learn more about electric water heater repair and water heater thermostat testing and replacement.
Water heater elements
Water heater elements are sized by wattage.
Most common is 4500 watt. Duel element water heaters are usually wired into a 30 amp. double pole breaker. Each side of the breaker will supply 120 volts.
Water heating elements types are flange, raised flanged and screw type. Flange style element bolt onto the tank. Screw type, of course, screw into the tank.
Screw in elements are the most common. Flange elements are sometimes hard to find. There is an adapter kit to convert a water heater with flange elements into screw type elements.
You can purchase high or low density elements. Low density elements cost more but have a longer life expectancy. They will heat the same amount of water as high density elements without getting as hot. This will cut down on sediment build up and increase the life of your tank.
Learn more about electric water heater repair and water heater elements.
Common electric hot water heater repair problems
Lost of power, usually where the electric wiring is connected together at the top of the water heater.
These wires can get very hot and sometimes burn into. They will also get hot and cause the breaker to trip.
Sometimes water is hotter than normal.
If you use just enough hot water to cause the lower element to heat, the water that is heater will rise to the top of the tank. The longer the element heats the higher the temperature at the top of the tank. Temperatures can rise much higher than the thermostat setting. This is called short cycling.
The most common electric water heater repair problem is element failure.