Plant + year + month letter
1606B13871
February 2006.
Furnaces & AC / Lennox
How old is my Lennox HVAC unit?
LennoxChange
Ad space (kept empty until an ad network is approved)
Where to find the serial number
Look for “Serial” or “S/N” near the service connectionsLennox serial formats we can read
Dark = year, orange = month or week.
Coverage and sources
Supports the 10-character plant/year/month layout used since 1973. The first two digits identify the factory. The letter I is skipped; L means November.
References checked 2026-10-26.
- www.building-center.org/lennox-hvac-age/
- www.lennox.com/lib/legacy-res/pdfs/lennox_model_and_serial_nomenclature.pdf
Independent reference tool, unaffiliated with Lennox. Sources & method