Age of Reliance water heater is shown on serial number located on side of tank: first digit is letter. Next two digits are numbers: for example C06 means 2006. Serial number also shows model number & wattage of elements in case you need new element from hardware store.
B) If cold outside temperatures are not to blame, your water heater may have a bad thermostat or element. Narrow down the suspects:
Water heater is 240Volts since you have more than 1 thermostat. Water heater has some hot water. This tells us upper element is working. And that water heater electricity is working. And that reset button is not tripped. And that heater is not experiencing run-away overheating event.
3) Burned or shorted wire. Turn off power. Open covers on side of tank. Remove insulation. Inspect parts for signs of high heat and burning. Especially lower element. Tighten any loose wires. Replace part that shows signs of burning. Put insulation and cover back over thermostats so cooler outside temperature doesn't cause thermostat to misread tank temperature.
Electric water heater can be repaired by homeowner.
Four things can cause NO hot water: 1) ECO red reset button tripped. Remove top cover on water heater, push red reset button on thermostat. Put insulation and cover back over thermostat. 2) Circuit breaker is tripped, circuit breaker bad, or wire loose in breaker box. Turn breaker on-off and listen for crackling or fizzing sound, and burned smell. Test breaker for 220Volts. Test top two screws on upper thermostat to see if water heater has electricity. 3) Bad upper thermostat. Replace upper thermostat. http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html 4) Bad upper element. Test upper element. http://waterheatertimer.org/How-to-test-water-heater-element.html
According to Reliance's trouble shooting guide, you may have faulty upper thermostat that is overheating, which is causing the high temp limit switch to open and shut it down. Pushing the reset switch is only a temporary solution until you find out what is causing it to shut down. Is it still under warranty? Call Reliance and find out. 1-800-365-4054
I personally wouldn't replace a safety device (placed there by lawyers, lawsuits and the all knowing government) with anything other than OEM. While it's very likely that one manufacturers flammable vapor sensor may interchange on another brand of tank, I think it's highly unlikely that EVERY manufacturers sensor will work on every other brand of tank
Here you are Dorothy
AO Smith code 991
Solution for error code 991
Check the gas type of the water heater. Inspect the environment around the water heater. ... Check if there is grease and/or dirt in the burner (Part #101) and the fan motor (Part #103), especially if the water heater has been installed in a contaminated area.
Thermocouple is the issue most likely
page 17 in link.
if your heater has a fame arrestor it may be dirty and restriction air into combustion chamber
http://www.reliancewaterheaters.com/media/72552/100264285-RELIANCE-N3-GAS-ULN.pdf
Why Does My Electric Water Heater Reset Button Keep Tripping?
So the red reset button on your electric water heater keeps popping out and needing to be reset.
Here's the most likely problem: The water in your water heater is getting too hot.
When the water temperature in your water heater exceeds 180°, the red reset button (also known as the high-limit switch) trips. This tripping protects you from getting scalded or burned when using hot water in your home.
OK, but then what's causing the water in your water heater to get so hot? The most likely cause is a bad thermostat.
How a bad thermostat causes your water heater reset button to trip
Electric water heaters have a lower and upper thermostat-one for each heating element.
The thermostats are responsible for controlling the heating elements. When the water has cooled off, the thermostats kick on the heating elements to heat the water. And once the water has reached your desired temperature, the thermostats shut off the heating element.
(This is very similar to the way your heating and air conditioning thermostat controls your home HVAC system.)
But these thermostats can go bad. When they do, they sometimes get stuck in the "on" position. This means that that the heating element continues to heat your water, eventually causing the high-limit switch to trip.
The fix: The bad thermostat needs to be replaced. A plumber can use a multimeter to test the thermostats and find out which one is bad.
Other problems that can cause your high-limit switch to trip
While a bad thermostat is the most common reason your water heater's reset button may trip, it's not the only one. Other common causes include:
A shorted heating element-It may be that the thermostat is working just fine and shutting off the heating element. But a short in the element is causing it to continue to heat your water.
Loose wiring-A loose wire in the water heater can generate heat that can cause the high-limit switch to trip.
Bad high-limit switch-The switch itself may be malfunctioning and tripping when it shouldn't be.
Get a professional plumber's help
Do you live in the Minneapolis-St. Paul area and need a reliable plumber to help you troubleshoot your water heater problem? Contact MSP Plumbing. We can usually fix the problem the same day.
