A.O. Smith Water Heater Age by Serial Number
Since about 2008 the first two digits of an A.O. Smith family serial number are the year and the next two are the week; older ones start with a month letter. Type the serial number below for the exact month and year.
About A.O. Smith
A.O. Smith is the largest US water heater maker. State, Reliance, American, U.S. Craftmaster and many Whirlpool and Kenmore heaters come from the same company and use the same code.
Same serial code: State, Reliance, American Water Heater, U.S. Craftmaster, Whirlpool, Kenmore.
Where to find the serial number
Water heater: The rating plate is a sticker on the side of the tank, usually at eye level or just above the gas valve or the upper access panel. Many water heater labels also print the manufacture date, so check for that first.
How to read a A.O. Smith serial number
Since about 2008 the first two digits of an A.O. Smith family serial number are the year and the next two are the week; older ones start with a month letter.
About 2008 to today: starts with 4 digits
YY WW …
- Digits 1 and 2 are the year: 11 means 2011.
- Digits 3 and 4 are the week of the year: 15 is mid-April.
Example: 1115A123456
Older: starts with 2 letters
L M YY …
- The second letter is the month.
- The two digits after the letters are the year.
Example: AF04A093001
Older: starts with 1 letter
M YY …
- The letter is the month.
- The two digits after it are the year.
Example: L07A071460
Month letters: A = January, B = February, C = March, D = April, E = May, F = June, G = July, H = August, J = September, K = October, L = November, M = December (there is no I).
How long does a water heater last?
Most water heaters last 8 to 12 years. Yearly servicing, the local climate and how hard it works all move it within that range. Past 8 years, it is worth getting a replacement price before the unit fails, so you aren't forced into a rushed decision.
Questions
How do I tell how old my A.O. Smith water heater is?
Find the serial number on the data plate and read it with the A.O. Smith code: Since about 2008 the first two digits of an A.O. Smith family serial number are the year and the next two are the week; older ones start with a month letter. Or type it into the decoder on this page.
Is the manufacture date printed on the label?
Often, yes, especially on newer units and water heaters. Look for "Mfg. date", "MFD" or "Date of manufacture". If there is a printed date, it is more reliable than decoding the serial number.
Who makes A.O. Smith?
A.O. Smith is made by A.O. Smith Corporation. The same serial code is used by State, Reliance, American Water Heater, U.S. Craftmaster, Whirlpool, Kenmore.
How sure are these dates? Checked against official records (recall notices or data plates with printed dates). How we test the decoder.
Keeping an older water heater going
- Water heater anode rod: A new anode rod can add years to a tank that is not leaking yet.
- Water heater leak detector alarm: Cheap insurance for a tank near the end of its life.
- Water heater drain flush kit: Flushing sediment once a year helps an older tank.