Rheem makes water heaters, furnaces, air conditioners and heat pumps, and it owns Ruud, Richmond, Marathon and Paloma. Its water heater serials put the month and year in the first four digits after any letter prefix. Its furnace and AC serials from the 1970s to 2000s hide the date after a single plant letter in the middle of the serial.
Skip any letters at the start. The first two digits are the month and the next two are the year. If the first two digits are 13 or higher they are the week instead.
1209D01234 reads as December 2009.
Two sources agree City of Palo Alto Utilities, InterNACHI water heater dating chart, Building Intelligence Center
Find the single letter in the middle of the serial (often F, M, G, N or W). The two digits after it are the week and the next two are the year.
CB5D302F099903346 reads as week 9 of 1999.
Two sources agree Building Intelligence Center, PickHVAC, Energy Trust of Oregon furnace chart, InterNACHI inspector forum
On nine-digit serials the last two digits are the year and the two before them are the week.
123451872 reads as week 18 of 1972.
Two sources agree Building Intelligence Center, PickHVAC, Energy Trust of Oregon furnace chart
On tankless units with a period in the serial, one source reads the two digits before the period as the year and the two after as the month.
05.05-000021 reads as May 2005.
One source Building Intelligence Center
Another source reads the two digits before the period as the month and the two after as the year.
05.05-000021 reads as May 2005.
One source InspectAPedia
An air-source heat pump usually lasts 10 to 15 years. It runs in both seasons, so it logs more hours than a furnace or an AC alone.
How long does a heat pump last? · Should I replace my furnace? · Trane, Lennox, Bryant, InterNACHI
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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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