York, Luxaire, Coleman, Fraser-Johnston and Champion heating and cooling equipment all come from Johnson Controls and share a serial scheme. Since October 2004 the serial starts letter, digit, letter, digit, with the two digits forming the year. Before that, four letters led the serial and the third letter was the year on a 21-year cycle.
The first letter is the plant. The second and fourth characters together are the year. The third character is the month letter (A is January through H, then K is September, L October, M November, N December).
W0K5896070 reads as September 2005.
Two sources agree Building Intelligence Center, PickHVAC, Waypoint Property Inspection, Energy Trust of Oregon furnace chart
The second letter is the month and the third letter is the year. The year letters repeat every 21 years, so one letter can mean two years.
WAKM011379 reads as January 2001 or January 1980.
Two sources agree Building Intelligence Center, PickHVAC, Waypoint Property Inspection, Energy Trust of Oregon furnace chart, GPI furnace age chart
A gas furnace usually lasts 15 to 20 years. Well-maintained units in mild climates reach 25; units that run hard with dirty filters fail sooner.
How long does a furnace last? · Should I replace my furnace? · HVAC.com, Lennox, InterNACHI (15-25)
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The age you just looked up is the kind of fact that gets lost. A written record of serial numbers, install dates, repairs and who did the work saves the next owner, inspector or insurer from guessing.
A lifetime logbook for the house, organized by system, with room for serial numbers, install dates, repairs and contractors. It stays with the house for the next owner.
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