How old is my Williams unit?
Williams is part of Williams Furnace. 2 serial formats sourced across furnace.
Serial number decoder for Williams
Type the serial from the data plate, not the model number. Nothing is sent anywhere; the tables are in this page.
Format example: 13 AD
- Williams furnace serial numbers in the 1984 to 2004 format encode the year as letter 3 (table below) and the month as letter 2 (A=Jan..M=Dec, I skipped); day as digits 1-2 (source: building-center.org).
- Example: serial 13 AD decodes to January 1987.
- Williams's official lookup at williamscomfort.com returns warranty / registration lookup.
Decoder pages by product
Format eras
- 1984 to 2004 VERIFIED
## AAFurnace, Water Heater - era not stated PARTIAL
no date in serialFurnace
Official lookup: the authority
Open the official Williams lookup takes serial number; returns warranty / registration lookup; 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
- The era not stated format is only partially confirmed (PARTIAL (masked example)).
- The era not stated format is documented but not decodable here: no example serial.
- Style 1 is a separate DATE-CODE STICKER (DD + month letter + year letter), not the serial. Style 2 serial = WWYY#####. Year-letter chart ends at Z=2004 (page last updated 2013). williamscomfort.com/warranty-v2-temp/ = 200 (warranty claim form); williamscomfortprod.com redirects there.
Sources
- https://www.building-center.org/williams-hvac-age/
- img: WILLIAMS-Date-of-Manufacture-Serial-Number-Style-1.jpg (transcribed)
- img: WILLIAMS-...-Style-2.jpg
- https://williamscomfort.com/warranty-v2-temp/official