How old is it? Read the serial number
Pick the brand on the rating plate and type the serial. We cover 36 brands across 15 serial systems; 11 of them use a format the maker publishes.
Water heaters and tankless
- Bradford WhiteOfficial format
- A.O. SmithWidely documented
- RinnaiOfficial format
- RheemOfficial format
- WhirlpoolWidely documented
- StateWidely documented
- AmericanWidely documented
- RelianceWidely documented
- NavienWidely documented
- RuudOfficial format
- RichmondOfficial format
- BoschOfficial format
- U.S. CraftmasterWidely documented
Boilers
- Weil-McLainOfficial format
Furnaces, air conditioners and heat pumps
- GoodmanOfficial format
- AmanaOfficial format
- CarrierOfficial format
- YorkWidely documented
- LennoxWidely documented
- TraneWidely documented
- American StandardWidely documented
- RheemWidely documented
- BryantWidely documented
- ColemanWidely documented
- LuxaireWidely documented
- Armstrong AirWidely documented
- DaikinOfficial format
- DucaneWidely documented
- HeilWidely documented
- RuudWidely documented
- TempstarWidely documented
- ComfortmakerWidely documented
- PayneWidely documented
- AirEaseWidely documented
- ArcoaireWidely documented
- KeepRiteWidely documented
Furnace and AC pages for the busiest brands
Brands we don't decode yet
- Nordyne / Nortek brands (Frigidaire, Maytag, Gibson, Tappan, Intertherm, Miller, Broan, Westinghouse): No serial with an independently known date found; format reported by inspectors only.
- Noritz: One real serial found; no maker statement.
- Takagi: Sources conflict.
- GE water heaters: Made by more than one company over the years; formats collide.
- Kenmore water heaters: Made by three different companies; the brand alone cannot pick a format.
- Lochinvar: Several conflicting formats; the plate prints the date, so read it there.
- Peerless: Only placeholder examples found.
- Burnham: Serials are sequential; the plate prints the date as MM/YYYY.
- Guardian, Champion: No source or dated serial found.
- Mitsubishi Electric, Fujitsu: Single-digit year (decade unknown) or no date code at all.
Not sure where the label is? Read how to read a rating plate.
Common questions
Why does the serial number tell you the age?
Most makers build the production date into the serial: a year and a month or week, sometimes as letters. The code differs by brand and has changed over the years, which is why the brand matters.
What if my label prints a manufacture date?
Use it. A printed date on the rating plate beats any decode. Many newer water heaters and some furnaces and AC units print one.
Why isn’t my brand listed?
We only list brands whose serial codes we could check against serials with known dates. 10 brand groups are left out for now, including the Nordyne family (Frigidaire, Maytag, Gibson, Intertherm), Noritz, Takagi and GE water heaters.
What do "Official format" and "Widely documented" mean?
Official means the manufacturer publishes how its serials encode the date. Widely documented means the maker doesn’t, but recall notices, service literature and inspector references agree on the rule, and it held up on dated serials we tested.