How to read a Rheem or Ruud serial number
- Skip any letters at the start. Many serials begin with a short letter code such as R, RH, RN, RHNG or RHLN. It isn’t part of the date.
- The next two digits are the month (01–12).
- The two after that are the year.
- A plant letter and a running number follow.
Rheem’s own guide uses the example 12 09 D 01234: December 2009, plant D [1]. InterNACHI, Energy Trust of Oregon, InspectAPedia and the Building Intelligence Center all read the code the same way[2][3][5][6].
RH 08 06 B17262 → skip RH, 08 = August, 06 = 2006 → August 2006
Check the label for a printed date first
Many newer Rheem and Ruud rating labels print “MFG. DATE” next to the serial. If yours does, use it: it’s the manufacturer’s own statement and needs no decoding.
Newer serials that start with a week
The Building Intelligence Center shows some newer Rheem serials where the first two digits are a week, not a month: A141511869 would be week 14 of 2015 [6]. InspectAPedia calls a week code uncertain[5], and no second source confirms the layout, so the decoder doesn’t read it. If the two digits after the letters are 13 or higher, they can’t be a month, and the decoder says so and points you to the printed date. For 01–12 there’s no way to tell from the number alone, which is another reason to check the label.
Worked examples
| Serial | How it reads | Made | Example from |
|---|---|---|---|
1209D01234 | 12 = month (December); 09 = year ’09 | December 2009 | Rheem Manufacturing |
RH0806B17262 | 08 = month (August); 06 = year ’06 | August 2006 | InspectAPedia |
RHLN0106534307 | 01 = month (January); 06 = year ’06 | January 2006 | Building Intelligence Center |
0794F12345 | 07 = month (July); 94 = year ’94Example 0794F***** filled in. | July 1994 | Energy Trust of Oregon |
0189123456 | 01 = month (January); 89 = year ’89Example "0189xxx"; digits added. | January 1989 | InterNACHI |
What this page doesn’t decode
- Week-first serials such as A141511869 or RHUNM181401735 (one source only).
- Tankless serials written like “05.05-000021”, which appear to put the year first (one source only).
Common questions
How do I find the age of my Rheem water heater?
Look for a printed MFG date on the label. If there isn’t one, skip the letters at the start of the serial; the next four digits are month then year.
Do Ruud water heaters use the same code?
Yes. Ruud serials read exactly like Rheem’s, and so do the Richmond and Vanguard tanks covered by the same charts.
Why doesn’t my Rheem serial decode?
Most often because the first two digits after the letters are above 12, which points to the week-first style, or because a model number was entered instead of the serial.
Not affiliated with Rheem or Ruud. Brand names are used only to say which serials this decoder reads.
Sources
- Rheem Manufacturing: How to locate and read your Rheem water heating serial numbersUsed for: Month + year after any letter prefix.
- InterNACHI (International Association of Certified Home Inspectors): InterNACHI Water Heater Dating ChartUsed for: Month + year after any letter prefix.
- Energy Trust of Oregon: Serial Number Decoder: Water Heater (PDF)Used for: Month + year after any letter prefix.
- Honest Home Inspections, LLC (hosted by InspectAPedia): How to determine Water Heater and Furnace Age (PDF, last updated 2009-01-06)Used for: Month + year after any letter prefix.
- InspectAPedia: Rheem Water Heater Age DecoderUsed for: Month + year after any letter prefix.
- Building Intelligence Center: Rheem Water Heater AgeUsed for: Month + year after any letter prefix.