Carrier, Bryant and Payne share a serial format: week and year in the first four digits, then a plant letter. A Carrier from 1985 to today decodes the same way. Nine-digit all-number serials from the 1980s put the year first.
The first two digits are the week and the next two are the year. The letter in the fifth spot is a plant code.
0519E28045 reads as week 5 of 2019.
Two sources agree Building Intelligence Center, PickHVAC, Energy Trust of Oregon furnace chart, McGarry and Madsen Home Inspection
On nine-digit all-number serials from the 1980s the first two digits are the year and the next two are the month.
850304091 reads as March 1985.
Two sources agree Building Intelligence Center, PickHVAC
A central AC condenser usually lasts 12 to 15 years. In hot climates where it runs most of the year, 10 is more typical; in the north, 20 is possible.
How long does a central air conditioner last? · Should I replace my air conditioner? · Bryant, Lennox, InterNACHI (7-15)
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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.
Galvanized, polybutylene, cast iron and the sewer line: what fails, what it costs, what insurance won't cover and how to decide.
A buyer's guide to older homes: wiring, pipes, lead, asbestos, insurance refusals and what the repairs actually cost.
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