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How old is my American Water Heater tankless water heater?

Serial number age decoder for American Water Heater tankless water heaters: 1 format era, the decode rule in plain English, transcribed tables, and the official lookup.

Serial number decoder for American Water Heater tankless water heater

Serial no.

Type the serial from the data plate, not the model number. Nothing is sent anywhere; the tables are in this page.

Format example: 1210A002243

American Water Heater tankless water heater serial numbers in the 2008 to present format encode the year as digits 1-2 (YY) after optional leading S and the week as digits 3-4 (source: building-center.org).
Example: serial 1210A002243 decodes to week 10 of 2012.
American Water Heater's official lookup at americanwaterheater.com returns warranty status.

Format eras

2008 to present VERIFIED
####A######digits 1-2 (YY) after optional leading S

How to read the serial

2008 to present formatVERIFIED

Shape ####A###### · example 1210A002243 / S1318 F000046 / 1836111786352 · confidence high

Year: digits 1-2 (YY) after optional leading S
Week or month: week = digits 3-4
Plant: letter after the 4 date digits (unpublished)

Example: serial 1210A002243 decodes to week 10 of 2012.

Trap: Sub-brand applicability (State/American/Reliance/Whirlpool/Kenmore) is ESTIMATE: building-center a-o-smith page covers AO Smith; each sub-brand has its own page to fetch in fan-out. Century: 20YY only for this style.

Listed under A.O. Smith in the source; American Water Heater is named in that format's family.

Where the data plate is on a tankless water heater

On the side or bottom of the wall-hung cabinet, or inside the front cover on the frame.

General guidance, not brand-specific: the owner's manual or the installer can point to the exact spot. See the data plate guide.

For scale only: the InterNACHI Standard Estimated Life Expectancy Chart for Homes lists Instant (on-demand) Water Heater at 10 years of expected service (nachi.org). That chart is a guideline, not a prediction for your unit.

Official lookup: the authority

Open the official American Water Heater lookup takes serial; returns warranty status; URL verified live

This site is a reference built from published tables. The manufacturer's own lookup wins whenever the two disagree.

What we could not confirm

Johnson City, TN on the plate. Distributed under dozens of brands (Whirlpool, U.S. Craftmaster, Craftmaster, Lowes, Proline, Premier, Polaris, Champion...). Current style = A.O. Smith YYWW.