Rheem Water Heater Age Lookup
Rheem packs the manufacture date into the first digits of every serial number, across the Performance, ProTerra, Classic, and Marathon lines. Enter yours to get the exact age and build date in seconds. Free for homeowners, plumbers, and inspectors.
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Finding Your Rheem Serial Number
Works on Performance, Professional, Marathon, and tankless models. Check these four spots.
Gas model shown. Spots are the same on Rheem electric tanks.
Where to Look
Performance and Professional gas models: the rating label wraps the jacket just above the gas control valve.
Rheem tankless units: check the right side or the bottom edge of the cabinet.
What You're Looking For
Rheem's Manufacturer's Rating Label is a printed grid signed Rheem Sales Company, Montgomery, Alabama. Serial No. is the very first row, directly above the model number, and that's the number to enter above.
- The top row of the grid, labeled "Serial No."
- Usually a letter followed by 9 digits (e.g. Q121561200)
- Many Rheem labels also print a "Manufacture Date" line in plain text, and if yours does, you already have your answer
- Rheem Sales Company, Montgomery, Alabama printed at the bottom left
Can't find it? Rheem badges the same tanks as Ruud, Richmond, and Vanguard, and the label sits in the same place on all of them. Marathon electric tanks put it on the side of the plastic jacket.
Rheem Serial Number Examples
Rheem tankless units use the same letter + week + year code as the tanks, and the Marathon electric line uses an all-digit month + year form (0189123456 = January 1989) that decodes here too.
Don't worry if yours looks different. Rheem has used week codes on modern tanks and month codes on older ones, and our decoder handles both, including serials typed without the leading plant letter.
About Rheem Water Heaters
Richard and Donald Rheem started the company in 1925 and put the Rheem name on water heaters in 1931. It is headquartered in Atlanta, majority owned by Paloma of Japan, and is one of the two companies that dominate North American water heating. Rheem is often credited with inventing the automatic storage water heater, but that was Edwin Ruud's work decades earlier, and Rheem acquired the Ruud company later.
Which Rheem you own depends on where it was bought. Performance and Performance Platinum are the Home Depot lines. Professional Classic, Professional Prestige and Triton go to plumbing wholesalers and cannot be bought retail, which is why a store cannot look up parts for one. Rheem also builds the tanks sold as Ruud, Richmond, Vanguard, Marathon, GE and Hotpoint. The catalog covers atmospheric and power vent gas, electric, gas tankless, and hybrid heat pump models, with EcoNet monitoring on the upper tiers.
Rheem serials begin with a one to four letter prefix identifying the plant and product, followed by four date digits and a sequence. On most units those four digits are the month and the year; some plants encode the production week instead, so a middle pair higher than 12 is a week rather than a month. R0988B10217, for example, reads September 1988: 09 and 88 behind the plant prefix. A leading CN marks a unit built for the Canadian market and is not part of the date, which trips up charts that start counting from the first character.
Where to find the serial
The serial is on a silver or white sticker wrapped around the top third of the tank, usually near the gas valve or the electric access cover. It's labeled SERIAL NO. and sits right next to the model number. On tankless and hybrid units the label is on the side panel instead. If the sticker is faded, snap a photo with your phone flash on and zoom in.
What the serial actually looks like
Why the age is worth knowing
Rheem residential warranties run 6, 8, 10, or 12 years depending on the model, and the clock starts at the manufacturing date on the sticker, not the install date. If your tank is creeping past year 10, start setting money aside and watch for rusty hot water or a pilot that won't stay lit.
Quick answers for this brand
What does the RHLN prefix on a Rheem serial number mean?
RHLN is one of Rheem's plant and product family prefixes. The four digits immediately after the prefix are the date code in week-year order (WWYY), so RHLN0820 means week 8 of 2020. Other Rheem plant prefixes like RHGN, RHBN, and RHWN follow the same pattern.
How do I tell a Rheem from a Ruud or Richmond by serial number?
You can't tell them apart by serial alone because Rheem manufactures all three brands using the same date code system on the same lines. Look at the model number prefix and the brand badge on the front of the tank. The age decodes the same way regardless.
Does Rheem's 12-year warranty start at install or at manufacture?
Rheem warranties begin on the date of original installation if you can prove it with a dated receipt, otherwise they default to the manufacture date plus 30 days. That's why decoding your serial matters - it sets the worst-case warranty clock.
Need a plumber?
Get free quotes from licensed local pros, no commitment required.
Share this tool with friends!
Know someone with an aging water heater? Send them a free check.