Official GSW warranty & serial services
Read the plate. Check the evidence.
Read a matching GSW water-heater year/month or year/week serial using GSW’s own documentation. Keep the model and complete serial from the rating plate.
Browse GSW manuals and guides →Check a documented system
Water heaters with confirmed manufacturer and numbering family; unrelated devices using the same name are outside these date-code rules.
Choose the equipment family
Match the product, manufacturer and documented serial layout before interpreting a date. The model is a separate label field; a date code alone does not identify capacity, installation date or warranty entitlement.
GSW’s official guide distinguishes older year/month codes from year/week codes from 2008, with an optional initial letter. Keep the entire serial: the manufacturer warranty form describes different lengths for 2008–2017 and later production. The chart’s corporate-history mention alone is not the source for this decoder.
Find GSW water heaters manuals →
GSW official serial-number age guide ↗
GSW official warranty form: serial length and production era ↗
Scope matters
Research reviewed October 16, 2026. This independent tool applies published rules and retains unresolved years and model candidates.
Reviewed historical ten-numeric-digit serials, optionally prefixed by a letter, using GSW’s pre 2008 month system.
The worked example U 0106413635 is June 2001. A general YYstill needs century context; the upper era cap does not invent an earliest manufacture year. Do not transfer this GSW layout automatically to American or every A. O. Smith water heater.
Select only after confirming the water heater or boiler family and numbering system described here. Brand ownership alone does not establish this system.
The explicit GSW manufacturer diagram U 1005 F 001234 and unprefixed form.
The manual calls the optional first letter a warranty code and maps nominal historical warranty terms; current entitlement is not calculated. The form elsewhere calls 2008–2017 serials 11 digits, whereas this optional-prefixed worked example has 12 characters: do not treat that wording as a universal validator. Weeks 1–53 are calendar validity bounds; the source does not establish ISO dates or plant geography.
Select only after confirming the water heater or boiler family and numbering system described here. Brand ownership alone does not establish this system.
Reviewed after 2017 numeric 13-character GSW serial shape from official 2019 Form 100 plus manufacturer FAQ prefix semantics.
The form states 13 digits after 2017 without publishing all possible suffix meanings. Only this conservative numeric shape is accepted; other letters/layouts need manufacturer confirmation. No exact date, plant or model is inferred.
Select only after confirming the water heater or boiler family and numbering system described here. Brand ownership alone does not establish this system.
Reading your result
Some systems reuse letters or only encode the last one or two year digits. Every supported interpretation is retained. A decade supplied from reliable records can narrow the reading; the tool does not automatically pick the newest year.
Usually the model is a separate plate field. Where published serial ranges actually identify a model, the result shows model candidates and links to their manuals. Overlapping ranges remain ambiguous.
After a lookup, the address includes the serial in a fragment beginning with #serial=. Use “Copy share link” to share the serial and selected context. Opening the link runs the same lookup. The fragment is not a query-string result page.