The water heater suddenly stopped working. The power light isn't on. Also, I tried switching the breakers off and on and that did not help.

Check the breaker first and confirm that power is being delivered to unit. Then if power is confirmed, try the reset and make sure that power is now getting to the heating coils. If necessary, you can always jump the reset switch if it stays stuck.

http://waterheatertimer.org/Water-heater-is-tripping-breaker.html

http://waterheatertimer.org/Figure-Volts-Amps-Watts-for-water-heater.html

http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#new

Check watt rating and wire size
Gene

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http://waterheatertimer.org/Water-heater-is-tripping-breaker.html

Gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Copy following link for tankless troubleshoot resources:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html#fuse
Tankless are not protected from surge, but there is a 3-5 amp glass fuse located on circuit board.
Check outlet with circuit analyzer, and multimeter

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

If it was working and recently stopped working, the heating element that heats the water probably went bad, no longer functioning. Check to make sure that there is or is not a reset button, and if there is, press and reset the heater. It's not difficult to remove the old heater element and replace it, but make sure the circuit breaker power to the water heater is off when you remove it. Take it to a water heating supply store, or large hardware store with the Brand and model number of your water heater (Reliance RELIANCE ELECTRIC WATER HEATER,model 606 ) to buy another one.

If you have tankless, then open following link before calling service technician.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

If you have ordinary tank-type electric water heater, then reset button is probably tripped out, or circuit breaker is not delivering power to heater.
Reset circuit breaker, then open cover located on side of tank and push in ECO red reset button.
http://waterheatertimer.org/How-to-troubleshoot-electric-water-heater.html
http://waterheatertimer.org/How-water-heater-thermostat-works.html

If you have boiler or indirect heater or solar heater or faucet-type heater, I would need more information, and might not be able to provide best answer.

Upvote the help.
And take advantage of fixya expert assistance live.
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If I understand correctly, you have electric water heater.
Heater suddenly stopped heating.

Four things cause sudden loss of water heater.
1) Reset button located under the top cover is tripped > turn off power, remove cover, press reset button > if reset keeps tripping, go to the troubleshooting link shown below.
2) Electric power to heater is interrupted > check circuit breaker > test for voltage > look for loose wire on breaker
3) Upper element burned out > test and replace element
4) Upper thermostat bad > replace upper thermostat

Reset button is best suspect.
Here is a link for complete troubleshoot and homeowner repair of electric water heater:
http://waterheatertimer.org/How-to-troubleshoot-electric-water-heater.html

Hi,
Check the top thermostat... right above it is a red button that you will have push hard on to reset...
If all that checks out then you have a bad top element...replace that...

heatman101

Could be water available safety switch that is out either due to bad switch or actual loss of water due to solenoid etc.

First, of course, check your breaker in the breaker box. You will need to check to see if the heater is getting power before checking the element(s). Elements go out suddenly, so this could be your problem if you have a smaller one-element heater. Have it checked. Good luck.