At fifteen years of age it would be less cost over time and labor to replace the whole tank. How efficient is your old one and being it runs hot all the time you could have a tank that will not last very long anyway. Mine sprung a leak at 18 years and made a big mess.
If you still have your owner's manual, you will need to call the manufacturer. They will need the model # & serial #. This particular brand has a fine mesh filter screen on the bottom (below the burner) that gets clogged and causes irregular pilot outages. They have a recall in which they will send you a new burner assembly with a reset switch built-in to it. They will send it to you for free, but you will need to hire your local propane co (at your expense) to install it and also clean the filter while they have the burner assembly out. Good luck. Douglas
Age of water heater is shown in serial number. First character is letter. Second 2 characters are numbers, which are year of manufacture. For example 05 is year 2005.
2) Two things known for sure: - electricity is OK - upper element is working because there is some hot water.
3) Three things can cause problem you describe: - Loose wire located from upper thermostat to lower element and thermostat. - Upper or lower thermostat is bad - Lower element is burned out
4) How to troubleshoot and repair - Turn off power, open covers and look for loose and burned wiring, especially on lower element. - When finished, put back insulation and covers so thermostat not exposed to cooler temperatures. - Burned wire on lower element is evidence that lower element is burned out.
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.
