Serial Number Age

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American Water Heater 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.

Decode a American Water Heater serial number

Type it exactly as printed. Spaces and dashes don't matter.

About American Water Heater

American Water Heater, based in Johnson City, Tennessee, has been owned by A.O. Smith since 2011. Its serials start with the year and the week. (Some guides say the third and fourth digits are the month; a 2001 recall notice shows they are the week.)

Same serial code: A.O. Smith, State, Reliance, U.S. Craftmaster, Whirlpool, Kenmore.

Where to find the serial number

WATER HEATERMODEL NO.SERIAL NO.1115A123456
The serial number is usually labelled "Serial No." Example in the American Water Heater format.

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 American Water Heater 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 …

  1. Digits 1 and 2 are the year: 11 means 2011.
  2. Digits 3 and 4 are the week of the year: 15 is mid-April.

Example: 1115A123456

Older: starts with 2 letters

L M YY …

  1. The second letter is the month.
  2. The two digits after the letters are the year.

Example: AF04A093001

Older: starts with 1 letter

M YY …

  1. The letter is the month.
  2. 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 American Water Heater water heater is?

Find the serial number on the data plate and read it with the American Water Heater 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 American Water Heater?

American Water Heater is made by A.O. Smith Corporation. The same serial code is used by A.O. Smith, State, Reliance, 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