A. O. Smith water heater age by serial number
A. O. Smith water heaters made since 2008 start the serial with the year and the week, and older units use a month letter after a plant letter. This A. O. Smith serial number lookup checks both styles to find the A. O. Smith manufacture date.
Where do I find the serial number?
On an A. O. Smith tank, the rating label is on the front of the jacket, usually above the gas valve or the thermostat covers. Read the serial from the line marked serial number, as the model number sits nearby and is easy to confuse with it.
How to read a A. O. Smith serial number
From 2008 on, an A. O. Smith serial starts with four digits: the year, then the week. 1210A002243 reads as week 10 of 2012. Before 2008, the first character is a plant letter, the second is a month letter and the next two digits are the year.
Year, week, then sequence
- Used
- 2008 to present
- Format
- Year, week, then sequence
- Example
- 1210A002243
Example, read
Plant letter, month letter, two-digit year
- Used
- Before 2008
- Format
- Plant letter, month letter, two-digit year
- Example
- ME98-0041362-917
- Months
- A to M, with I skipped. J is September, M is December.
Example, read
The month letters A to H, for January to August, are well documented. The letters for September to December are less certain.
Where to find the serial number
On an A. O. Smith tank, the rating label is on the front of the jacket, usually above the gas valve or the thermostat covers. Read the serial from the line marked serial number, as the model number sits nearby and is easy to confuse with it.
Brands with the same format
State uses the same serial format as A. O. Smith for the year, week, then sequence format (2008 to present).
Questions
How old is my A. O. Smith water heater?
If the serial starts with four digits, read them as year and week. 19021234567 reads as week 2 of 2019.
What does a serial like ME98-0041362-917 mean?
That is the pre-2008 style. M is the plant, E is the month and 98 is the year, so it reads as May 1998.
How certain are the older month letters?
Sources agree on A to H for January to August. For September to December they disagree, so we use J, K, L and M and mark those months as less certain.
Does State use the same serial format as A. O. Smith?
For units made from 2008 on, yes. Before 2008, State serials put the month letter first with no plant letter.
Can a week-coded serial tell me the month?
Roughly. We convert the week to a part of a month, so week 10 of 2012 is early March. The exact day is not in the serial.
Can I look up a A. O. Smith model number here?
No. An A. O. Smith model number describes the heater's fuel, capacity and series. For age, type the serial number instead.