Rheem Water Heater Age: Month or Week in the Serial Number?
Rheem water heater serial numbers use two main date structures. From 1981 through August 2012, the date field is MMYY: two digits for the month followed by two digits for the year. For example, split serial number 1209D01234 as 12 | 09 | D | 01234. It represents December 2009. D identifies the plant line, and 01234 is the unit sequence. Rheem’s own records support this reading from August 1993. Dates from 1981 through July 1993 come from labels transcribed by building inspectors, so Appliage marks them as estimates.
After August 2012, most Rheem serial numbers use a plant letter followed by WWYY. Split M301703203 as M | 30 | 17 | 03203: M is the plant code, 30 is the production week, 17 means 2017, and 03203 is the unit sequence. The plant and sequence fields identify the individual water heater but do not influence its manufacture date.
Appliage decodes two Rheem water heater date structures. From September 2012, a plant letter comes first and the four digits after it give the production week and then the year, so M301703203 is week 30 of 2017. From 1981 through August 2012, the first four date digits give the month and then the year, so 1209D01234 is December 2009. Serial dates before 1981 are refused.
Shape decides which structure applies. Without a letter in front of the four date digits, the month and year structure applies. When a plant letter comes first, the two digits after it are the production week and the next two are the year, and Appliage uses that structure whenever the week and year land after August 2012.
Rheem Water Heater Serial Number
- legacy date MMYY
- modern date WWYY after plant prefix
- remainder plant/sequence
| Rheem structure | Date field | How to read it |
|---|---|---|
| 1981 through August 2012 | MMYY | Month first, then two-digit year |
| After August 2012 | Plant letter + WWYY | Production week first, then two-digit year |
In the older structure, 1209 means month 12 of 2009. Some serial numbers place letters before the MMYY field. In RN0197147899, the date field 0197 means January 1997. In RHNG0804P000036, 0804 means August 2004. Rheem’s published material anchors this format from August 1993; readings from 1981 through July 1993 are labeled as inspector-sourced estimates.
In the later structure, the plant letter comes immediately before WWYY. For example, split W071725046 as W | 07 | 17 | 25046. W identifies the plant, 07 is the production week, 17 means 2017, and 25046 is the unit sequence. The plant code tells Rheem where the water heater was made, while the sequence identifies the individual unit. Neither field influences the manufacture date.
A 2016 recall also shows the newer layout on serial numbers beginning with plant letter A, M, or Q followed by week-and-year prefixes from 0114 through 5214 or 0515 through 1615.
Rheem Serial Numbers Appliage Cannot Find the Age
Rheem has also used other layouts, including tankless serial numbers that place the year before the month. Appliage returns no date when a serial number fits neither format above. It also refuses MMYY readings before 1981 because no reviewed source supports extending this table that far back.
Many rating plates print the manufacture date directly, and Rheem’s warranty lookup can check the serial separately. Rheem and Ruud air conditioners, furnaces, and heat pumps use different serial-number systems, so they are outside this water-heater guide.
Ruud tanks follow the same two readings
Ruud water heaters use the same two date structures. Select Ruud in Appliage when that is the name printed on the rating plate.
An A. O. Smith water heater age lookup puts the year first and the production week second. A Bradford White water heater age lookup writes its year and month as two letters. Read either one as a Rheem serial and you get the wrong date.
Sources
- Rheem serial number label instructions. Rheem breaks down 1209D01234 into the month, year, factory and unit sequence.
- Rheem water heater age lookup. Rheem uses M301703203 and W071725046 as examples.
- Rheem water heater warranty procedure. Rheem changed from month then year to week then year after August 2012.
- CPSC: Rheem water heater recall (16-177). The affected A, M and Q serials include week and year codes 0114–5214 and 0515–1615.
- CPSC: Rheem and Ruud tankless water heater recall (07-108)
For other brands, see our appliance serial number lookup.