Rheem water heater date code: month and year in the first four digits
Rheem says the serial number on its water heating rating labels has ten characters. The first two give the month of manufacture and the next two give the year.
How does Rheem lay out the serial?
| Characters | Rheem's example | Meaning (Rheem's label) |
|---|---|---|
| 1–2 | 12 | Month Manufactured |
| 3–4 | 09 | Year Manufactured |
| 5 | D | Plant Line Code |
| 6–10 | 01234 | Consecutive serial number |
Read that way, Rheem's example serial 1209D01234 was built in December of year 09. Rheem's page covers its water heating products. This rule is not confirmed for Rheem air conditioners or furnaces.
What does my serial say?
Type the serial to see the month and year.
Which century is a two-digit year?
The year is two digits. Our reader reads 09 as 2009, as Rheem's example does, and switches to 19xx only when 20xx would be in the future. If that reading does not fit what you know about the unit, trust the label and the maker over our reader.
Where is the serial?
Rheem's page says the serial number is on the product rating label. Copy it exactly, including any letters.
Sources
- Rheem, How to locate and read your Rheem water heating serial numbers: https://www.rheem.com/how-to-locate-and-read-your-rheem-water-heating-serial-numbers/, accessed 2026-10-27