Whirlpool water heater age by serial number
The serial number is on the data plate on the front of the heater. On a Whirlpool water heater the first two digits of the serial are the year and the next two are the week. This is not the code used on Whirlpool appliances.
Decode a Whirlpool serial number
How to read a Whirlpool serial number
Year and week, first four digits
The first two digits are the year and the next two are the week of that year.
Shape: ten digits, or four digits, a letter and six digits. Newer serials can be thirteen digits.
9950123040 reads as week 50 of 1999 (around December).
Where to find the serial number
The data plate is on the front of the tank jacket.
If the serial number does not decode
- Whirlpool-brand water heaters are built by the American Water Heater Company, an A. O. Smith company, under licence from Whirlpool. The serial follows American’s format, not the format of Whirlpool appliances.
- Whirlpool-brand serials often have a letter in the fifth position, as in 1104T403904. The first four digits still give the year and the week.
- The small print at the bottom of the plate names the company that built the heater. Store brands changed makers over the years.
What the age tells you
| Equipment | Typical service life |
|---|---|
| Tank water heater | 10 to 15 years |
| Tankless water heater | about 20 years |
About Whirlpool
Whirlpool Corporation of Benton Harbor, Michigan builds major appliances under the Whirlpool, Maytag, KitchenAid, Amana and JennAir names. Whirlpool-brand water heaters are a separate business, built by the American Water Heater Company under licence.
Brands that share this serial system: American, A. O. Smith, State, Reliance.
Questions and answers
Which characters in a Whirlpool serial number show the date?
The first two digits are the year and the next two are the week of that year. This applies to units built since at least the late 1990s.
Who makes Whirlpool water heaters?
Whirlpool-brand water heaters are built by the American Water Heater Company, an A. O. Smith company, under licence from Whirlpool. The serial follows American’s format, not the format of Whirlpool appliances.
Sources
- CPSC recall: American Water Heater Company gas water heaters, serials starting 0124 to 0127 sold June to September 2001 (US Consumer Product Safety Commission): https://www.cpsc.gov/Recalls/2001/cpsc-american-water-heater-co-announce-recall-to-replace-burners-in-gas-water-heaters
- CPSC recall 19-029: A. O. Smith ultra-low NOx water heaters, serial ranges by build date (US Consumer Product Safety Commission): https://www.cpsc.gov/Recalls/2019/A-O-Smith-Recalls-Ultra-Low-NOx-Water-Heaters-Due-to-Fire-Hazard
- Building Intelligence Center: American water heater age (independent reference): https://www.building-center.org/american-water-heater-age/
- InspectAPedia: American water heater age (independent reference): https://inspectapedia.com/plumbing/American-Water-Heater-Age-Manuals.php
- Building Intelligence Center: Whirlpool water heater age (independent reference): https://www.building-center.org/whirlpool-water-heater-age/
Formats last checked against these sources on October 5, 2026. Found a serial that does not fit? Send a correction. How formats are verified: method and sources.