80 gal Whirl Pool electric water heater. Does it have 1 thermostat or 2?

it does have 2 elements they are located under the 2 panels on the heater you will find them under the covers on the front they will be connected to the thermostats follow the wiring. besure to turn off the power before working on it and use a tester to double check

Test elements.
http://waterheatertimer.org/How-to-test-water-heater-element.html
If elements test out, then replace both thermostats.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

More resources:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html
Otherwise, if you have some hot water, then power to unit is good and probably at least 80% rated voltage, breaker is good, and upper element is at least functional and probably working perfectly, reset button is not tripping so tank is not overheating.

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

Hello Joseph

Test elements.
http://waterheatertimer.org/How-to-test-water-heater-element.html
If elements test out, then replace both thermostats.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

More resources:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html
Otherwise, if you have some hot water, then power to unit is good and probably at least 80% rated voltage, breaker is good, and upper element is at least functional and probably working perfectly, reset button is not tripping so tank is not overheating.

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

1) For gas: Turn off gas to heater:
http://waterheatertimer.org/images/Gas-water-heater-89-valve-2.jpg

2) For electric: Turn off circuit breaker.
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#veryhot

3) For gas: Copy following link to identify gas control valve thermostat, and troubleshoot by type of gas control.
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

4) For gas: Gas control valve thermostat has probably gone bad.

5) Add comment and give clear description of water heater.

6) Call plumber.

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

1) Copy following link for troubleshooting newly installed electric water heater:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#new

2) Push in rest button on upper thermostat.

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

Thermostat is top, and ECO with reset goes in bottom closest to electric element.

Is this electric water heater?
Does it have 1 or 2 elements?
http://waterheatertimer.org/How-to-wire-water-heater-thermostats.html
http://waterheatertimer.org/images/WH-w-combined2-1000.jpg
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

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

Check all wiring at water heater and possible upper thermostat is bad, and in need of replacement.

1) All 2-element tanks are 240 volts.
I replace both thermostats
Be sure to put insulation and covers back when finished so thermostats not exposed to cool air that will cause temperature misread.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
http://waterheatertimer.org/How-to-test-water-heater-element.html

2) How thermostats work
http://waterheatertimer.org/How-water-heater-thermostat-works.html

3) You have multimeter, so you're right there.
Take 30 minutes and do complete water heater troubleshoot.
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

4) Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, expert speaks with you over phone while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

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