How old is my water heater, AC or furnace? Decode the serial number
Most water heaters, air conditioners, heat pumps and furnaces carry their date of manufacture inside the serial number on the rating plate. Choose the brand, type the serial, and Age From Serial reads the date with the rule the manufacturer published, then shows the age, the rule it used and the source.
Every rule has a source
Each format comes from a manufacturer document or a U.S. government recall notice, with the date we last checked it. Forums and blogs are never the basis of a result, and a brand read with its parent company's rule is labelled as such.
No guessed dates
When a code fits two years, you see both and how to tell them apart. When a format has no published rule, the result says so instead of inventing a date.
Stays on your device
Decoding is done by your browser. The serial and model numbers you type are not sent to us or to anyone else.
Water heaters
- Bradford White
Bradford White
- Rheem
Rheem, Ruud (Rheem-built), Richmond (Rheem-built)
- A. O. Smith family
A. O. Smith, State, Reliance, American, U.S. Craftmaster, Whirlpool (2011-2016), Kenmore (2011-2016)
- Lochinvar
Lochinvar (residential tanks)
Air conditioners, heat pumps and furnaces
- Carrier and Bryant
Carrier, Bryant
- Trane
Trane, American Standard (inferred), RunTru (inferred)
- Goodman, Amana and Daikin
Goodman, Amana, Daikin
- Lennox
Lennox
- Nortek (Nordyne) brands
Frigidaire, Gibson, Maytag, Westinghouse, Tappan, Intertherm, Miller
Why a serial can give two dates
Manufacturers save space on the plate. Some print only two year digits, so the century is left to the reader; some use a letter for the year and start the alphabet again every twenty years. Where the published rule cannot tell the decades apart, the decoder lists every reading the rule allows and drops only those that are impossible, such as a date after today. The installation paperwork, the building permit or simply the look of the plate usually decides the rest.
What the date is good for
The date of manufacture is the starting point for warranty questions, for planning a replacement and for checking what a home inspection report says. It is not the installation date, which can be months or even years later, and it does not by itself tell you which refrigerant an air conditioner uses. The refrigerant guide explains why, and the service life page shows what ENERGY STAR publishes about typical ages.
Cannot find the label? The data plate guide shows where to look on each type of equipment. To see how the rules were chosen, read methodology and sources.
Page updated . Decoding rules last checked against their sources on the date shown with each source.