Water heaters date-code guide

Rheem Water Heaters serial number lookup

Many Rheem water-heater serials place a month/year code near the beginning, sometimes after a plant letter. The decoder validates both month and week variants.

Parent: Rheem Manufacturing
Common code: After an optional plant letter, four digits commonly encode month/year; some lines use week/year.
Reviewed: August 8, 2026

Instant equipment lookup

Decode the manufacturing date

Runs on this device

Equipment type

Manufacturer or brand

Using After an optional plant letter, four digits commonly encode month/year; some lines use week/year.

Serial number

Type exactly what is printed. Spaces and dashes are ignored.

Optional: add model number for capacity cluesAdd model

Model number

Model decoding is labeled as a clue unless the exact format is documented.

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EQUIPMENT DATA

MODEL24ABC636A003

SERIAL5019X30312

WeekYear

See exactly how the code was read

SerialAtlas highlights the date characters, names the matching rule, and shows alternative interpretations when the code is ambiguous.

Current age calculated automatically
Confidence and rule source shown
Optional model-capacity clue

How to read a Rheem Water Heaters serial number

After an optional plant letter, four digits commonly encode month/year; some lines use week/year. SerialAtlas removes spacing and punctuation, then applies only the documented rule families mapped to Rheem Water Heaters. The lookup remains in the browser.

Try this documented-style exampleM092504723Load example

Equipment covered

gas tank water heaters
electric tank water heaters
heat-pump water heaters
tankless water heaters

Commercial, imported, very old, specialty, and private-label equipment can use a different code. Confirm the full rating plate before accepting a result.

Where to find the rating plate

Upper or lower side of the tank jacket
Near the gas control valve on gas models
Behind an electrical access panel
Side or bottom edge of a tankless cabinet

Why more than one date can appear

Two-digit years and repeating letter cycles can point to more than one era. SerialAtlas ranks the plausible dates but keeps materially different alternatives visible. Label design, refrigerant, installation records, and product literature can resolve the era.

Source and verification

Inspector Handbook open reference data (CC BY 4.0). Independently implemented and reviewed August 8, 2026.

Open reference source

What this result does not prove

A manufacture date is not an installation date, warranty decision, recall match, condition assessment, or replacement recommendation. Confirm high-stakes decisions with the manufacturer or a qualified professional.