Free serial decoder
Rheem water heater age
Type the serial number from the label. We skip the letters in front, read the date digits, and show when it was made.
Same code: Ruud, Richmond.
Decode your Rheem serial
It's on the label, after "Serial" or "S/N". Not the model number.
How to read Rheem serial numbers
Digits 1 and 2 are the month, digits 3 and 4 the year. A single letter first means week and year instead.
- 08Month
- 15Year
- AFactory
- 12345Unit number
0815A12345: 08 = August, 15 = 2015. Made August 2015. The A after the date is the factory.
- RHNGPrefix
- 06Month
- 10Year
- BFactory
- 12345Unit number
RHNG0610B12345: Skip the RHNG prefix. 06 = June, 10 = 2010. Made June 2010.
- QFactory
- 23Week
- 16Year
- 012345Unit number
Q2316012345: One letter first means week and year: Q = factory, week 23 of 2016. Made around June 2016.
Example serials, made up to show the format.
A printed date wins. If the label prints a manufacture date, use it instead of the serial.
Letters to skip
Prefixes before the month and year:
RRHRNRNGRHLNRHNGRHUNRU
Factory letters
One of these first means week and year:
AMQCW
Where's the serial number?
On the rating label on the side of the tank. On some electric models it sits near the bottom. On tankless models, check the side or top of the unit. Many Rheem labels also print a MFG DATE, and that date beats the serial.
Rheem warranty
When it starts
Starts on the install date if you can show it. Without proof, it starts 90 days after the heater was made.
New owner?
Depends on the model. Many Rheem water heater warranties cover the original owner only, so check your model's warranty.
How long
Home tanks are usually 6 to 12 years on the tank and parts, by product line. On many models it's the number after the T or S in the model number (XG50T12 = 12 years).
General terms only. Your model's warranty, and Rheem's lookup, have the final word.
How long it lasts
10 to 15 yrs
Tank water heaters
20+ yrs
Tankless water heaters
Planning ranges from the U.S. Department of Energy, not deadlines. LA and Orange County's hard water can shorten them, so yearly flushing matters. Which kind do you have?
Questions
How do I tell how old my Rheem water heater is?
First look for a MFG DATE on the label. Many Rheem labels print one. If not, find the serial number. On most Rheem tanks the first 4 digits are the month and year, so 0815 is August 2015. Skip any letters in front, like R, RH, or RHNG.
What if my Rheem serial starts with one letter, like A, M, or Q?
That letter is the factory, and the next 4 digits are the week and the year. Q2316 means week 23 of 2016, which is June. Rheem's service bulletin describes this format starting at its Mexico plants in 2012.
Is a serial starting with A1015 from October 2015?
No. With one letter first, 10 is the week, so A1015 is week 10 of 2015, which is early March. The 2016 CPSC recall notice for Rheem electric water heaters lists A1015 serials as made in March 2015.
Do Ruud and Richmond use the same code?
Yes. Rheem's service bulletin on reading serial numbers covers Rheem, Ruud, and Richmond. Many GE water heaters were made by Rheem and use the same month and year code.
How do I read a Rheem tankless serial with a dot?
Guides disagree on serials like 09.04-000021. Some read it as year then month (April 2009), others as month then year (September 2004). We show both. The date on the label or Rheem's lookup settles it.
When does the Rheem warranty start?
Starts on the install date if you can show it. Without proof, it starts 90 days after the heater was made.
Do I need to register my Rheem water heater?
Check your model's warranty, because some lines depend on it. For example, Rheem's Marathon lifetime tank warranty must be registered within 90 days of install, or it drops to 10 years.
How long do Rheem water heaters last?
The U.S. Department of Energy says tank water heaters usually last 10 to 15 years and tankless heaters more than 20. Hard water and skipped flushing can shorten that.
Rather snap a photo?
The full Water Heater Check reads the label, asks a few taps, and tells you what it needs.
Open the Water Heater CheckOther serial guides
Sources
Checked November 4, 2026. We aren't affiliated with Rheem.