Rheem water heater age by serial number
The serial number is on the rating label on the heater. On a Rheem water heater built since 2012, the serial starts with a letter, then two digits for the week and two for the year. Older serials start with the month and the year.
Decode a Rheem serial number
How to read a Rheem serial number
Rheem has used 2 serial formats. Find the one that matches the shape of your serial.
Plant letter, then week and year
The letter just before the digits is the plant. The first two digits after it are the week and the next two are the year.
Shape: one letter, then nine digits. A brand prefix such as GE or RHUN can come first.
M141209135 reads as week 14 of 2012 (around April).
Rheem changed over one plant at a time: Mexicali in April 2012, Nuevo Laredo in June 2012 and the others later. A serial from 2012 or 2013 can therefore be in either layout. Plant letters: A Montgomery, Alabama; C Canada; M Mexicali; Q Nuevo Laredo; W Water Heater Innovations.
Month and year, first four digits
Skip any letters at the start. The first two digits are the month and the next two are the year.
Shape: four digits, a letter and five digits, or ten digits. Up to five letters such as RH, RHLN or GENG can come first.
RH0806B17262 reads as August 2006.
Where to find the serial number
The serial is on the rating label on the tank jacket. On recent electric models the label is near the bottom of the heater.
Newer rating labels print the date of manufacture on the third line. Older plates may print “MFG. DATE” as a month and year.
If the serial number does not decode
- A tankless serial printed with a period, such as 05.05-000021, is not decoded here. References disagree on which pair of digits is the year.
- Rheem counts warranty from the manufacture date and can verify it from the serial number.
- The manufacturer can confirm the date from the serial: Rheem registration, warranty or serial lookup.
What the age tells you
| Equipment | Typical service life |
|---|---|
| Tank water heater | 10 to 15 years |
| Tankless water heater | about 20 years |
About Rheem
Rheem Manufacturing Company of Atlanta has been owned by Paloma of Japan since 1988. Rheem bought Ruud in 1960 and launched the Richmond water heater line in 1983. Rheem and Ruud share one serial code for water heaters and a different one for furnaces and air conditioners.
Brands that share this serial system: Ruud, Richmond, GE.
Questions and answers
Which characters in a Rheem serial number show the date?
The letter just before the digits is the plant. The first two digits after it are the week and the next two are the year. This applies to units built since 2012.
Why does my Rheem serial number look different?
Rheem has used 2 serial formats: plant letter, then week and year (built since 2012); month and year, first four digits (built until 2012 or 2013). The decoder tries each one.
How do I tell the two layouts apart?
Look at where the letter sits. One letter followed by nine digits is the newer layout: the first two digits are the week and the next two the year. Four digits followed by a letter and five more digits is the older layout: the first two digits are the month and the next two the year. Letters in front of the four digits, such as RH or GENG, are a brand and fuel prefix and are skipped.
Sources
- Rheem Technical Service Bulletin 1207: how to locate and read Rheem, Ruud and Richmond serial numbers (manufacturer): https://cdn.globalimageserver.com/FetchDocument.aspx?ID=67e23d33-c085-48fa-8aa8-eab53d38296b
- CPSC recall: Rheem electric water heaters, serial ranges for units built in 2014 and 2015 (US Consumer Product Safety Commission): https://www.cpsc.gov/Recalls/2016/Rheem-Recalls-to-Repair-Water-Heaters
- Building Intelligence Center: Rheem water heater age (independent reference): https://www.building-center.org/rheem-water-heater-age/
- Rheem: how to locate and read your water heating serial numbers (manufacturer): https://www.rheem.com/how-to-locate-and-read-your-rheem-water-heating-serial-numbers/
- InspectAPedia: Rheem water heater age decoder (independent reference): https://inspectapedia.com/plumbing/Rheem-Water-Heater-Age-Decoder.php
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.