For example, split modern serial number 1601123456789 as 16 | 01 | 123456789. The code 16 means 2016, 01 means production week 1, and 123456789 identifies the individual water heater. When the full printed serial begins with a valid YYWW code, the serial is enough for Appliage to return the production week and an estimated age. Appliage also reads the legacy letter formats below for water heaters made from 1991 through 2007.
Appliage decodes two State date structures. From 2008, the serial opens with four digits: the first two are the year and the next two are the production week, so 1601123456789 is week 1 of 2016. For 1991 through 2007, the serial opens with a month letter, or with a factory letter and a month letter, then two digits for the year, so M07A009387 is December 2007. Both are covered under State Water Heater Age Rules below.
The first character tells the two apart: a digit opens the year and week structure, and a letter opens the older month letter structure.
State Water Heater Age Decodes
State serial numbers from 2008 onward
A. O. Smith’s serial-number guide confirms the year-and-production-week positions used for State water heaters.
The first two digits are read as a 2000s year, so 17 means 2017. The next two digits must be between 01 and 53. The remaining digits identify the individual unit but do not influence its manufacture date.
State serial numbers before 2008
Older State water heaters use the month and year instead of the production week. Check whether the serial number begins with one letter or two letters before reading the date.
| Legacy structure | How to read it | Example | Manufacture date |
|---|---|---|---|
| One letter, then two digits | The letter gives the month, and the next two digits give the year. | M07A009387 | December 2007 |
| Two letters, then two digits | The first letter identifies the factory, the second letter gives the month, and the next two digits give the year. | AF04A093001 | June 2004 |
Two month tables apply, depending on the year. State’s own serial-number FAQ published the table for 1991 through 2002, and that table includes the letter I. From 2003 the letters follow a table without I, so the same letter can shift by one month between eras.
| Month code, 1991–2002 one-letter serials | Month |
|---|---|
| A | January |
| B | February |
| C | March |
| D | April |
| E | May |
| F | June |
| G | July |
| H | August |
| I | September |
| J | October |
| K | November |
| L | December |
| Month code, 2003–2007 and all two-letter serials | Month |
|---|---|
| A | January |
| B | February |
| C | March |
| D | April |
| E | May |
| F | June |
| G | July |
| H | August |
| J | September |
| K | October |
| L | November |
| M | December |
State’s FAQ, archived in 2001 and again in 2002, spells out the 1991–2002 table: A means January, I means September, and L means December. Its own worked example dates serial prefix C00 to March 2000.
The 2003–2007 table skips the letter I so that it is not confused with the number 1. A 2004 recall registration record prints single-letter prefixes A03 through M03 across all twelve months of 2003. A 2005 CPSC recall lists prefixes such as AF04 for June 2004 and M04 for December 2004, and a 2008 CPSC recall prints L07 and M07 serial ranges, placing those tanks in November and December 2007.
Two-letter serials pair a factory letter with a month letter from the no-I table. A 1992 CPSC recall prints MD91 through MG91 for tanks built April through July 1991, and the same two-letter style appears in recall records into 2004.
These letter dates are anchored from 1991 through 2007, and the two-letter style ended in June 2004. Outside that span, Appliage returns no date instead of guessing.
Examples
The first two examples use the modern format. Examples 3 through 5 use the legacy letter formats, which Appliage reads for 1991 through 2007.
State Serial Number Example 1: 1734106145074
The result is production week 34 of 2017 (Estimated).
- Split serial number 1734106145074 as 17 | 34 | 106145074.
- The year code 17 means 2017, and the week code 34 means production week 34.
- The final nine digits, 106145074, are the unit sequence and do not influence the manufacture date.
Therefore, the estimated manufacture date is production week 34 of 2017.
Legacy Serial Number Example 2: M07A009387
The result is December 2007 (Estimated).
- The serial number begins with one letter, so use the legacy one-letter structure.
- The month code M means December.
- The following digits 07 mean 2007. The remaining characters are not needed to find the manufacture date.
- This exact serial number opens an A. O. Smith range in a 2008 federal recall, and State tanks in the same recall share the layout.
Therefore, the estimated manufacture date is December 2007.
State Serial Number Example 3: AF04A093001
The result is June 2004 (Estimated).
- The serial number begins with two letters, so use the older two-letter structure.
- The first A is the factory code, and the month code F means June.
- The following digits 04 mean 2004. The remaining characters are not needed to find the manufacture date.
Therefore, the estimated manufacture date is June 2004.
State Serial Number Example 4: A00114092
The result is January 2000 (Estimated).
- The serial number begins with one letter, so use the legacy one-letter structure.
- The digits after the letter, 00, mean 2000. That year sits inside the 1991–2002 span, so the FAQ table that includes I applies.
- The month code A means January. The remaining digits are not needed to find the manufacture date.
Therefore, the estimated manufacture date is January 2000.
State Serial Numbers Appliage Cannot Find the Age
Appliage reads the legacy letter formats only for 1991 through 2007, because no verified record dates the letter codes outside that span. A letter date outside those years returns no date, and a two-letter serial with a date after June 2004 also returns no date. It also does not force a nine-digit SAP number or an older digits-only serial through the modern YYWW rule. For example, it will not treat 103475818 as a 2010 week-34 date, or treat the opening 89 in serial number 893045678 as 2089. For a nine-digit SAP number, look for BUILD DATE or a separate YYWW code on the rating plate.
A month letter outside its own era also returns no date. M is not a month in the 1991–2002 table, where December was L, and I is not a month from 2003 on, where September became J.
For the modern format, Appliage returns no date when the encoded year is earlier than 2008, the production week is outside 01–53, or the opening digits are unreadable. Check the rating plate again before deciding which structure applies.
State and A. O. Smith Use the Same YYWW Structure
Current service material places State and A. O. Smith in the same serial-number matrix, and a federal recall reads the same year and week positions on both brands. Older labels may carry the State Industries name.
In October 2016, A. O. Smith introduced a nine-digit SAP serial. A barcode may capture only that number and omit the date code. If the rating plate also prints a full serial beginning with YYWW, read the first four digits in the usual way. The A. O. Smith water heater age lookup explains the same distinction on A. O. Smith-branded units.
Manufacture Week, Installation Date, and Warranty
The serial number gives the week in which the water heater was made. It does not tell you when a plumber installed it, when it was first used, or when warranty coverage began. Those dates can be different.
The model number is useful for parts and replacement planning. The age, however, is calculated from the year and production-week fields in the State serial number. For warranty information, enter the serial number on State’s warranty verification page.
Sources
- State Service and Warranty Guide. The manual explains the year and week positions in a State serial example.
- A. O. Smith serial number change notice (2016). The notice says the barcode captures only the nine-digit SAP serial and does not include the date code.
- State serial number FAQ (archived 2001). The FAQ lists the 1991–2002 month letters, including I for September, and uses C00 for March 2000.
- CPSC: A. O. Smith water heater recall (92-016). Tanks with prefixes MD91–MG91 were made from April to July 1991.
- Water heater recall registration (04-128, archived 2004). The registration record includes A03–M03 and two letter prefixes from K02 to J03.
- CPSC: A. O. Smith and State water heater recall (06-002). The notice lists month and year prefixes from January 2004 to July 2005.
- CPSC: A. O. Smith water heater recall (08-241). The affected A. O. Smith and State tanks include L07 and M07 serials from late 2007.
- CPSC: A. O. Smith and State water heater recall (19-029). The notice identifies prefixes 1115–1631 as production year and week.
For other brands, see our appliance serial number lookup.