How do I determine the age of my unit?It is a Rheem model # 81X-80D

I can't find any information on that MODEL you listed in your question. It's sort of like the Rheem Air Handler models but notthing comes back. In any case you will NEED the SERIAL number, as that will tell you all you need to know about it. If you can't decipher SN, call RHEEM and they can give you the info on that unit. Sorry I could not be of more help.

Do you mean size?... height, width, and diameter of a specific model?
Or do you mean the length of warranty coverage. You will need serial number located on label on side of tank.
Or do you mean age of water heater?

Suggest contacting Rheem.com

http://waterheatertimer.org/Water-heater-warranty-by-brand.html
http://waterheatertimer.org/pdf/Find-Age-of-water-heater.pdf

Gene


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

you have trash in the valve .shut it down take the valve apart clean it . also maintenance on this unit is needed.seal can be bad also. hope it helps.send pictures of the unit and age and model serial number.

Add a comment and include brand, model, type and approx age of water heater for possible help.

http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html

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

If the drip is coming out of drain valve: Put a hose cap over end of drain valve.
If water is seeping out of cracked drain vale, then replace it.
If the leak is seeping around previously sealed threads, then tank may be rusted beyond repair.
http://waterheatertimer.org/How-to-replace-water-heater-drain-valve.html
http://waterheatertimer.org/Leaking-water-heater.html

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

call plumbing supply house with serial #, & model #of your tank. give them the info and if they handle the brand of your tank , they should be able to help.

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

You need to first determine if the burners light or not.

As long as the unit wasn't run with a dry tank the unit should not have been affected by continuous water running, unless it got hot enough to damage the thermocoupler which is an easy replacement. That is the part that your pilot/ignitor warms so that the gas valve will open the gas line to the burners.

The tank may be corroded and you may need a new unit. Check to make sure that the water is not coming from any of the water connections that are higher up on the unit. Also check the drain plug to make sure it's secure. I don't know the age of the water heater but it may be time to replace. Most people don't know that water heaters require maintenace (draining the tank to remove sediment) from time to time.

my 50 gal heater puts out only 20 gal of hot water