Rheem water heater age from the serial number
On a Rheem or Ruud tank, the date sits right after the letter prefix: two digits for the month, two for the year. Type your serial and the tool returns the build date.
Rheem and Ruud water heater age finder
Paste the serial number exactly as printed, letters included. Spaces and dashes are ignored.
Results are estimates of the manufacture date. The rating plate and Rheem support are the authority.
Where to find the Rheem water heater serial number
The Rheem water heater serial number is on the rating plate, the label on the side of the tank, and the Rheem water heater age comes from it. The serial usually starts with a few letters, such as R, RH, RHLN, RHNG or RU, then a run of digits. Some plates also print the manufacture date as “MFG. DATE”. If yours does, trust it over the serial.
Photograph the whole plate. Ruud water heaters use the same code as Rheem, so this page covers both.
Rheem water heater serial number age: how the date code works
After the letter prefix, the first two digits are the month and the next two are the year, MMYY. The serial RH 0806B17262 reads as 08, 06: August 2006, and the plate on that unit also prints “MFG. DATE: 08/2006”. The serial R 0884B10488 is August 1984.
The tool accepts a letter prefix of up to four letters, then a month from 01 to 12, then two digits for the year. The rest is a sequence number. InterNACHI groups Ruud with Rheem and gives the same rule.
- Letters first: R, RH, RHLN, RHNG, RU and similar
- Digits 1 and 2 after the letters: month, 01 to 12
- Digits 3 and 4: year
Worked examples, including one the tool cannot date
The first four examples are documented Rheem serials. The last is a newer week-based serial, which the tool does not read because 14 is not a month.
| Serial | Reading | What the tool shows |
|---|---|---|
| RH 0806B17262 | 08 = month, 06 = year | August 2006 |
| R 0884B10488 | 08 = month, 84 = year | August 1984 |
| RHLN 0106534307 | 01 = month, 06 = year | January 2006 |
| RHNG 0804P000036 | 08 = month, 04 = year | August 2004 |
| A141511869 | Week-based layout: week 14 of 2015 | Can't date this serial |
The tool reads the digits after the prefix as a month. A week number of 1 to 12 will read as a month instead.
Why Rheem needs a second look
Rheem has used several layouts over the years, and a few newer ones put a week of the year where the month goes. A141511869 is week 14 of 2015, and RHUN M181401735 is week 18 of 2014, according to the Building Intelligence Center.
The tool rejects any serial where those first two digits are above 12, so most week-based serials come back as “can’t date”. But a week-based serial with a week from 1 to 12 will be read as a month. The year digits are still right, so the age is close, but the month can be off by several months.
We found no official Rheem document for the serial code, and Rheem’s own online decoder did not return readable text when we checked. The rule rests on three third-party references and one plate with a printed date, so we rate it medium confidence. Treat the year as dependable and the month as an estimate.
What the tool cannot read
When the tool cannot date a serial it says so, and shows where to find the serial on the plate.
Week-based serials above week 12
A first pair of digits above 12 is not a month, so the tool says it cannot date the serial.
Other prefix styles
Serials with no letter prefix, or a longer one, may not match. Check that you copied the whole serial.
GE-branded Rheem-built tanks
GE tank water heaters use the same layout and have their own page. Newer GE heat pump models may use a different code.
How long does a Rheem water heater last?
The finder measures age against a typical water heater life of 12 years. Rheem’s own guide on repair or replace puts a conventional tank at 8 to 12 years. The NAHB study lists 10 years for a gas tank and 11 for an electric tank, and the Department of Energy puts storage tank water heaters at 10 to 15 years.
So a Rheem near 12 years is a unit to inspect: check the base for leaks and the water for rust, and weigh the repair history. Our water heater lifespan guide covers the signs of failure.
Put the Rheem age on the unit's record
Entering a month and year once is easy. Remembering it for 300 units is not. In Invendoory, a water heater is an item in the unit’s inventory with its serial, install date, expected life and a photo tagged as the serial plate. The life-used bar shows green under 60%, amber from 60% to 80% and red above that.
That lets a supervisor plan replacements by life used. See the asset inventory, the water heater age guide or the Appliance Age Finder.
Rheem water heater age questions
How do I read a Rheem serial number?
After the letter prefix, the first two digits are the month and the next two are the year. RH 0806B17262 is August 2006. The plate may also print a manufacture date, and that is more reliable than the serial.
Does Ruud use the same code as Rheem?
InterNACHI groups Ruud with Rheem and gives the same month-and-year rule, so the tool reads Ruud serials the same way. Both appear under one entry in the finder.
Why can't the tool date my Rheem?
Some newer Rheem serials carry a week of the year where the month goes. If the first two digits are above 12, the tool cannot date it. Look for the printed manufacture date on the plate or contact Rheem support.
Is the Rheem date the install date?
No. It is the manufacture date. The install date is usually a few months later. If you have the install date, use that for depreciation and warranty. The serial date is a good stand-in when you do not.
How accurate is the Rheem rule?
The month-and-year layout is confirmed by several third-party references and one plate with a printed date. We found no Rheem document, so we rate it medium confidence. The year is dependable. The month may be off if the serial uses a week.
Sources
- Building Intelligence Center – Rheem water heater age
- InspectApedia – Rheem water heater age decoder
- InterNACHI Water Heater Dating Chart (Rheem and Ruud)
- NAHB and Bank of America Home Equity, Study of Life Expectancy of Home Components (2007)
- U.S. Department of Energy, Energy Saver Guide (2022)
- Rheem, Water Heater Lifespan: When to Repair vs. Replace
Checked October 2026.
Keep the age of every water heater on file
The finder dates one tank. Invendoory keeps the serial, install date and life used for every water heater in every unit. Open the live demo, no signup needed.