How old is my GSW unit?
GSW is part of A.O. Smith Corp. 7 serial formats sourced across water heater.
Serial number decoder for GSW
Type the serial from the data plate, not the model number. Nothing is sent anywhere; the tables are in this page.
Format example: 1210A002243
- GSW 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.
- GSW water heater serial numbers in the 2008 to present format encode the year as digits 1-2 after any leading letter (20YY) and the week as digits 3-4 (month if built before 2008 per GSW FAQ) (source: building-center.org).
- Example: serial U1117 F700633 decodes to week 17 of 2011.
- GSW water heater serial numbers in the 2008 to present format encode the year as digits 1-2 (YY, 20YY) after any leading letter and the week as digits 3-4 (source: building-center.org).
- Example: serial 1924115263020 decodes to week 24 of 2019.
Decoder pages by product
Format eras
- before 2010 VERIFIED
A##A######Water Heater - 2008 to present VERIFIED
####A######Water Heater, Heat Pump Water Heater, Tankless Water Heater - 2008 to present VERIFIED
A#### A######Water Heater - 2008 to present VERIFIED
#############Water Heater - before 2008 VERIFIED
AA##A######Water Heater - before 2007 VERIFIED
##### #####Water Heater - 1970 to 1979 VERIFIED
A##-A-##-######Water Heater
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
- No official online lookup URL was verified for GSW.
- Canadian brand (Fergus, ON). gsw-wh.com/faq/ (200) carries the official decode text: first two digits = year, next two = month before 2008 / week after 2008, ignore leading letter.
Sources
- https://www.building-center.org/a-o-smith/
- https://www.building-center.org/gsw-water-heater-age/
- https://gsw-wh.com/faq/official
- img: GSW-style-2.jpg
- https://www.building-center.org/american-water-heater-age/
- https://www.building-center.org/whirlpool-water-heater-age/
- https://www.building-center.org/u-s-craftmaster-water-heater-age/
- https://www.building-center.org/craftmaster-water-heater-age/
- https://johnwoodwaterheaters.com/faqs/official