How old is my Aire-Flo furnace?

Serial number age decoder for Aire-Flo furnaces: 2 format eras, the decode rule in plain English, transcribed tables, and the official lookup.

Serial number decoder for Aire-Flo furnace

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: 5899L17212

Aire-Flo furnace serial numbers in the 1973 to present format encode the year as digits 3-4 (YY) and the month as letter at position 5 (A=Jan .. M=Dec, I skipped) (source: building-center.org).
Example: serial 5899L17212 decodes to November 1999.
Aire-Flo furnace serial numbers in the before 1972 format encode the year as digits 1-2 and the month as digit(s) 3(-4), 1-12 (source: building-center.org).
Example: serial 6512 decodes to December 1965.

Format eras

1973 to present VERIFIED
####A#####digits 3-4 (YY)
before 1972 VERIFIED
####digits 1-2

How to read the serial

1973 to present formatVERIFIED

Shape ####A##### · example 5899L17212 · confidence high

Year: digits 3-4 (YY)
Week or month: month = letter at position 5 (A=Jan .. M=Dec, I skipped)
Plant: digits 1-2 = factory/plant code

Month code	Month
A	January
B	February
C	March
D	April
E	May
F	June
G	July
H	August
J	September
K	October
L	November
M	December

Example: serial 5899L17212 decodes to November 1999.

Trap: Looks identical to Carrier style 1 (WWYY L #####). Century ambiguous (99=1999 vs 2099 not an issue, but 06=1906/2006 needs era). Lennox official lookup accepts formats ####A#####, A##A######, AA##A##### which implies newer alpha-prefixed formats NOT covered by building-center; treat those as low-confidence until sourced.

Listed under Lennox in the source; Aire-Flo is named in that format's family and the corporate link is an estimate, not a checked fact.

before 1972 formatVERIFIED

Shape #### · example 6512 · confidence low

Year: digits 1-2
Week or month: month = digit(s) 3(-4), 1-12

Example: serial 6512 decodes to December 1965.

Trap: 3-4 char serial; ambiguous month split (e.g. 651 = 1965 Jan or ...)

Listed under Lennox in the source; Aire-Flo is named in that format's family and the corporate link is an estimate, not a checked fact.

Where the data plate is on a furnace

Inside the furnace: remove the upper (burner) access door and look on the inside of the door, on the blower compartment wall, or on a sticker facing you at the burner deck.

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 Furnace at 15 to 25 years of expected service (nachi.org). That chart is a guideline, not a prediction for your unit.

Official lookup: the authority

Open the official Lennox lookup takes serial (####A#####, A##A######, AA##A#####); returns Your Product's Coverage; 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

Aire-Flo is treated as sharing Lennox's format because the source lists it in that family; the corporate relationship itself is an estimate.
No official online lookup URL was verified for Aire-Flo.
Building-center: 'Aire-Flo is a Lennox trade name for their economy line; serial numbers follow Lennox styles' (style 1 1606B13871 shown). aire-flo.com is an unrelated Columbus OH contractor; no official brand site or lookup found - use the Lennox lookup.