Start with the label format
For a legacy Rheem-built GE tank, ignore a recognized leading badge such as GE, GENG or RN, then read month and year. GENG0601D13586 means June 2001. Building Intelligence Center, InterNACHI and Honest Home Inspections agree on this older tank rule.
This legacy reading is bounded to 1970–2016. GE’s support page separates traditional heaters made before January 2017 from those made July 2019 onward. A GE logo alone is not enough to apply the old Rheem rule to a newer tank.
Two letters, six digits and a final letter
GE Appliances publishes a different chart for this layout: the first letter is the month and the second is the year. The month codes are A, D, F, G, H, L, M, R, S, T, V and Z for January through December. These are not consecutive letters.
The year letters repeat roughly every twelve years. This result is labeled per maker and lists documented candidates since 1970. For example, AD can point to January 1978, 1990, 2002, 2014 or 2026. Compare the model’s production period and manual date; the serial alone cannot choose the correct cycle.
GeoSpring and tankless units need context
GE’s support article distinguishes several GeoSpring generations and traditional tanks. Use that product history to narrow a letter-code result. Tankless equipment supplied by another maker is not covered by the legacy tank rule; identify the OEM before trying another brand’s decoder.
Common questions
Why are there several possible dates?
GE reuses year letters. The tool does not silently choose the newest date, because a much older appliance can carry the same code.
What if neither format fits?
Use GE’s product-specific support guide with the full model and serial. Do not use a refrigerator-style chart just because the tank has a GE badge.
Where is the number?
The rating label is on the side of the unit. A printed MFG date is preferable to a code inference, and an installation date remains a separate event.
Worked examples
| Serial | Style | How it reads | Made | Example from |
|---|---|---|---|---|
1108903259 | Legacy Rheem-built tank: month + year | 11 = month (November); 08 = year ’08 | November 2008 | Building Intelligence Center |
GE09022246884 | Legacy Rheem-built tank: month + year | 09 = month (September); 02 = year ’02 | September 2002 | Building Intelligence Center |
GENG0601D13586 | Legacy Rheem-built tank: month + year | 06 = month (June); 01 = year ’01 | June 2001 | Building Intelligence Center |
AD123456A | GE appliance letter code — per maker | A = month letter (January); D = year letter (1978, 1990, 2002, 2014 or 2026) | January 1978, 1990, 2002, 2014 or 2026 | Constructed to show the rule |
Not affiliated with GE. Brand names describe decoder compatibility. Manufacture date is not installation date.
Sources
- Building Intelligence Center: ge water heater ageUsed for: Legacy Rheem-built tank: month + year.
- InterNACHI (International Association of Certified Home Inspectors): InterNACHI Water Heater Dating ChartUsed for: Legacy Rheem-built tank: month + year.
- Honest Home Inspections, LLC (hosted by InspectAPedia): How to determine Water Heater and Furnace Age (PDF, last updated 2009-01-06)Used for: Legacy Rheem-built tank: month + year.
- GE Appliances: Appliance manufacture date code chartUsed for: GE appliance letter code — per maker.
- GE Appliances: Water heater support by product and manufacture period