AO Smith water heater age from the serial number
Current A. O. Smith serials start with the year and the week. Type yours and the tool returns the build date. Older letter serials are covered too.
A. O. Smith water heater age finder
Paste the serial number exactly as printed, letters included. Spaces and dashes are ignored.
Results are estimates of the manufacture date. The rating plate and A. O. Smith support are the authority.
Where to find the AO Smith water heater serial number
The AO Smith water heater age is in the serial number on the rating plate, the label on the side of the tank. Photograph the plate, then copy the AO Smith water heater serial number. On a current unit, the first two digits are the year and the next two are the week of that year.
A. O. Smith publishes this rule in its service and warranty guide, so this is one of the better-sourced decoders in the tool. The company writes its name with periods, and many people search for it as AO Smith. Both mean the same brand.
AO Smith water heater age by serial number: how current serials work
For AO Smith water heater age by serial number, start with the digits. Since about 2008, the serial is mostly digits. The first two are the year, the next two are the week from 01 to 53, and the rest is a sequence number. A. O. Smith’s own example, 1719106145074, is week 19 of 2017.
Because the tool shows a week rather than a month, you will see results like “Week 19 of 2017”. Roughly four weeks make a month, so week 19 falls around May. A letter can sit inside the sequence, as in 1210A002243, which is week 10 of 2012. That year-and-week pair is the AO Smith date code.
- Digits 1 and 2: year (17 is 2017)
- Digits 3 and 4: week of the year, 01 to 53
- The rest is a sequence number
Older letter serials
Before about 2008, A. O. Smith used letters. In the two-letter style the first letter is a factory code and the second is the month. In the one-letter style the single letter is the month. Month letters run A for January to M for December and skip I.
| Serial | Pattern | What the tool shows |
|---|---|---|
| 1719106145074 | Year + week (current) | Week 19 of 2017 |
| 1836111786352 | Year + week (current) | Week 36 of 2018 |
| AF04A093001 | Factory letter, month letter, two-digit year | June 2004 |
| GG03-1495366-S29 | Factory letter, month letter, two-digit year | July 2003 |
| E07A135491 | Month letter, two-digit year | May 2007 |
The first two rows come from A. O. Smith’s guide. The letter examples come from the Building Intelligence Center.
What the tool cannot read
The current format is well supported. The older letter styles rest on two third-party references that agree on the structure. We left out some formats because the sources could not be reconciled:
- 1970s serials in the “A20-H-78” style
- An unexplained style such as “S1318 F000046”
- Any serial where the first four characters are not a plausible year and week
The InterNACHI chart gives AJ89 as October 1989, which does not fit its own month alphabet. Most sources skip the letter I, which makes J September, so we did not use that example in our tests. When in doubt, check the plate for a printed date.
Where the A. O. Smith code also applies
Related brands share rules or sit next to A. O. Smith on the tool.
State Water Heaters
State is an A. O. Smith brand and uses the same code. See State water heater age.
Whirlpool water heaters
InterNACHI lists Whirlpool-branded water heaters under American, an A. O. Smith company, with a year-and-week rule.
Other water heater brands
Bradford White, Rheem and GE each write the date differently.
How long does an A. O. Smith water heater last?
The finder measures age against a typical water heater life of 12 years. We did not find a published lifespan specific to A. O. Smith, so the useful numbers are the general ones. The NAHB study lists 10 years for a gas tank and 11 for an electric tank. Rheem gives 8 to 12 years for a conventional tank. The Department of Energy puts storage tank water heaters at 10 to 15 years.
A unit near 12 years is a unit to inspect, not a unit to replace on schedule. Look at the base for leaks, the water for rust and the repair history. Our water heater lifespan guide covers the signs.
Put the A. O. Smith age on the unit's record
A week number is easy to forget and awkward to compare. In Invendoory, you enter the install date and the expected life, tag a photo of the serial plate and the life-used bar does the comparison. Green is under 60%, amber is 60% to 80% and red is above 80%.
Then a supervisor can sort every water heater in the portfolio by life used instead of walking the units. See the asset inventory or the Appliance Age Finder for other brands.
A. O. Smith water heater age questions
How do I read an A. O. Smith serial number?
On current units, the first two digits are the year and the next two are the week of that year, from 01 to 53. A. O. Smith’s example, 1719106145074, is week 19 of 2017. Older units use letters for the month and two digits for the year.
What is the difference between AO Smith and A. O. Smith?
None. A. O. Smith is the company’s name. People often search for it as AO Smith. The tool reads both the same way, and this page covers the A. O. Smith brand and its serial code.
Why does the tool show a week instead of a month?
Current serials carry the week of manufacture, not the month. The tool shows the week as printed, such as week 19 of 2017, and uses it to estimate the age in years.
Do State and Whirlpool water heaters use the same code?
State is an A. O. Smith brand, so it uses the same code. Whirlpool-branded heaters are listed by InterNACHI under American, an A. O. Smith company, with the same year-and-week rule. The Whirlpool link is from third-party references.
What if my A. O. Smith serial can't be dated?
Check that you copied the serial and not the model number. Very old serials and some unusual formats are not covered. Look for a printed manufacture date on the plate, or contact A. O. Smith support with the model and serial.
Sources
- A. O. Smith Service and Warranty Guide, July 2024 (How to Read the Serial Number)
- Building Intelligence Center – A. O. Smith water heater age
- InterNACHI Water Heater Dating Chart
- NAHB and Bank of America Home Equity, Study of Life Expectancy of Home Components (2007)
- U.S. Department of Energy, Energy Saver Guide (2022)
- Rheem, Water Heater Lifespan: When to Repair vs. Replace
Checked October 2026.
Keep the age of every water heater on file
The finder dates one tank. Invendoory keeps the serial, install date and life used for every water heater in every unit. Open the live demo, no signup needed.