SerialAtlas
Offline-capable

11 supported labels

Water heater age lookup

Decode manufacture dates for tank, heat-pump, and selected tankless water heaters.

SerialAtlas field reference

How to tell how old a water heater is

Start with the serial number on the rating plate, not the model number or thermostat. Separate the model number and serial number before decoding: the serial can support a manufacture-date estimate, while the model identifies the product family and configuration.

The supported water-heater families are not interchangeable: A. O. Smith-family labels commonly use year and production week, Rheem-family labels can expose month/year or week/year, and Bradford White uses repeating letter cycles.

A manufacture date is not an installation date, condition assessment, or warranty answer. Use invoices, permits, registration records, and official manufacturer support when the decision matters.

  • Photograph the complete rating plate and distinguish model from serial
  • Choose the brand family before applying any date-code rule
  • Keep ambiguous or no-match results visible instead of forcing a year
  • Confirm warranty, parts, and safety questions with the manufacturer
Open universal decoder
Water heaters guideA. O. SmithA widely used style begins with two digits for year and two digits for production week (YYWW).Water heaters guideState Water HeatersA widely used style begins with two digits for year and two digits for production week (YYWW).Water heaters guideAmerican Water HeaterA widely used style begins with two digits for year and two digits for production week (YYWW).Decoder aliasReliance Water HeatersUses the verified A. O. Smith Corporation rule family.Decoder aliasU.S. CraftmasterUses the verified A. O. Smith Corporation rule family.Water heaters guideWhirlpool Water HeatersA widely used style begins with two digits for year and two digits for production week (YYWW).Decoder aliasLochinvar Water HeatersUses the verified A. O. Smith Corporation rule family.Water heaters guideBradford WhiteThe first letter is a repeating year code and the second letter is the month code.Water heaters guideRheem Water HeatersAfter an optional plant letter, four digits commonly encode month/year; some lines use week/year.Water heaters guideRuud Water HeatersAfter an optional plant letter, four digits commonly encode month/year; some lines use week/year.Water heaters guideRichmond Water HeatersAfter an optional plant letter, four digits commonly encode month/year; some lines use week/year.