How old is my Weil-McLain boiler?
Serial number age decoder for Weil-McLain boilers: 1 format era, the decode rule in plain English, transcribed tables, and the official lookup.
- Weil-McLain's official lookup at weil-mclain.com returns warranty / registration lookup.
Format eras
- 1988 to present VERIFIED
AA #######range lookup on the CP number (table)
How to read the serial
1988 to present formatVERIFIED
Shape AA ####### · example CP 2530051 · confidence high
- Year
- range lookup on the CP number (table)
- Week or month
- not encoded (year only)
Where the data plate is on a boiler
On the jacket: a plate or sticker on the front or side of the boiler casing, sometimes behind a removable front panel next to the gas valve or control.
General guidance, not brand-specific: the owner's manual or the installer can point to the exact spot. See the data plate guide.
For scale only: the InterNACHI Standard Estimated Life Expectancy Chart for Homes lists Boiler at 40 years of expected service (nachi.org). That chart is a guideline, not a prediction for your unit.
Open the official Weil-McLain 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 1988 to present format is documented but not decodable here: year position not parseable from prose: 'range lookup on the CP number (table)'.
- Date is NOT in the serial: it is the consecutive 7-digit 'CP' number on a separate tag. Official CP Lookup returns the manufacturing date (boilers only; EG/EGH not available; 6-digit numbers: prefix a zero, e.g. CP0123456). AquaBalance CP numbers are not sequential.
Sources
- https://www.building-center.org/weil-mclain-hvac-age/
- img: Weil-McLain-CP-Chart.jpg
- https://www.weil-mclain.com/cp-lookup/official