How old is my Peerless boiler?

Serial number age decoder for Peerless boilers: 3 format eras, the decode rule in plain English, transcribed tables, and the official lookup.

Serial number decoder for Peerless boiler

Serial no.

Type the serial from the data plate, not the model number. Nothing is sent anywhere; the tables are in this page.

Format example: 339090-200012

Peerless boiler serial numbers in the 2000 to present format encode the year as digits 1-4 after the hyphen (YYYY) and the month as last 2 digits (source: building-center.org).
Example: serial 339090-200012 decodes to December 2000.
Peerless boiler serial numbers in the 1984 to 1999 format encode the year as last 2 digits (19YY) and the month as first 2 digits after the hyphen (source: building-center.org).
Example: serial 123456-1284 decodes to December 1984.
Peerless's official lookup at peerlessboilers.com returns warranty / registration lookup.

Format eras

2000 to present VERIFIED
######-######digits 1-4 after the hyphen (YYYY)
1984 to 1999 VERIFIED
######-####last 2 digits (19YY)
before 1983 VERIFIED
######

How to read the serial

2000 to present formatVERIFIED

Shape ######-###### · example 339090-200012 · confidence high

Year: digits 1-4 after the hyphen (YYYY)
Week or month: month = last 2 digits

Example: serial 339090-200012 decodes to December 2000.

Trap: Unambiguous. building-center text shows 339030 and image 339090 for the same example.

1984 to 1999 formatVERIFIED

Shape ######-#### · example 123456-1284 · confidence high

Year: last 2 digits (19YY)
Week or month: month = first 2 digits after the hyphen

Example: serial 123456-1284 decodes to December 1984.

Trap: 4-digit MMYY suffix 1984-1999.

before 1983 formatVERIFIED

Shape ###### · example 123456 · confidence medium

Documented but not evaluated by the decoder: no year decode text.

Trap: Pre-1984: no date; contact Peerless or use ANSI date.

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.

Official lookup: the authority

Open the official Peerless 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 before 1983 format is documented but not decodable here: no year decode text.
Date is the suffix after the hyphen: YYYYMM since 2000, MMYY 1984-1999; pre-1984 plain 6-digit serials need Peerless.

Sources

https://www.building-center.org/peerless-hvac-age/
img: PEERLESS-Serial-Number-Style-1.jpg
img: PEERLESS-Serial-Number-Style-2.jpg
https://www.peerlessboilers.com/consumers/warranty/official