HVAC & water heater age decoder
How old is that furnace, AC unit, or water heater? Enter the brand and the serial number from the data plate — the year of manufacture is encoded in the serial, and this decodes it.
The data plate is the metal or foil sticker on the unit — outdoor units have it on the side panel, furnaces inside the front door, water heaters near the bottom. The ANSI/CSA year printed there pins down brands whose date codes repeat (Bradford White, A.O. Smith…).
How this works
Nearly every HVAC and water-heater manufacturer encodes the production date inside the serial number — usually the year and month or week, in a format that changed over the decades. This tool knows the serial formats for 741 brands, including sister brands that share a parent company's system (a Tempstar or Heil serial decodes with Carrier's rules; Ruud with Rheem's).
Why it matters: the age of the mechanicals is one of the biggest hidden costs in a home purchase. A typical AC condenser or water heater near the end of its expected life is a four-figure replacement the listing usually doesn't mention.
Some brands don't encode a date in the serial at all — for those, the tool says so honestly instead of guessing. The manufacture date is sometimes also printed directly on the plate.