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
Check these four spots on your Rheem water heater
Common Locations
What to Look For
- White or metallic manufacturer sticker
- Labeled "Serial No." or "S/N"
- Typically 8–12 characters long
- Usually near the model number
Can't find it? Try removing access panels or checking behind the temperature dial.
Rheem Serial Number Examples
Don't worry if yours looks different - Rheem has multiple formats and our system can decode most variations.
About Rheem Water Heaters
Rheem water heaters have earned their position as an industry leader through nearly a century of manufacturing expertise, beginning when brothers Richard and Donald Rheem founded the company in 1925. Headquartered in Atlanta, Georgia, Rheem operates as one of the world's largest producers of heating, cooling, and water heating products. The company pioneered numerous innovations including the first residential gas water heater in 1931 and continues to shape industry standards through investments in energy efficiency and smart home technology. Their products are sold through professional distributors and select retailers across North America.
The Rheem product portfolio encompasses traditional atmospheric gas models, power-vented systems, electric resistance units, tankless water heaters, and industry-leading heat pump hybrid models. Their Professional Prestige series delivers exceptional performance with features like self-cleaning technology that reduces sediment buildup and extends service life. Rheem's Marathon electric models feature a lifetime tank warranty thanks to seamless polybutene construction that eliminates corrosion concerns entirely. Many units achieve ENERGY STAR certification and UEF ratings exceeding 0.95, translating to significant energy savings over the product lifetime. The EcoNet smart monitoring system enables remote control and leak detection through smartphone integration.
Rheem supports customers through an extensive network of factory-trained contractors and service centers spanning all 50 states. Their Pro Network connects homeowners with qualified installers who understand proper sizing, venting requirements, and local code compliance. Warranty registration and support requests can be completed online, while technical service representatives provide phone assistance for troubleshooting and parts identification. The company's comprehensive model numbering system allows service technicians to quickly determine specifications, and their serial number formats reliably indicate manufacturing dates for maintenance planning and replacement decisions.
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.
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