Read the plate. Check the evidence.
Choose Maytag Neptune laundry or the separately documented historic Neptune water-heater label before decoding.
Browse Neptune manuals and guides →Check a documented system
Maytag Neptune laundry and separately confirmed historic American-family Neptune water heaters.
Choose the equipment family
Match the product, manufacturer and documented serial layout before interpreting a date. The model is a separate label field; a date code alone does not identify capacity, installation date or warranty entitlement.
For Neptune water-heater labels: the historical chart associates this label with American water heaters. A confirmed American tank may encode the two-digit year followed by the production week. This format is separate from appliance codes and does not encode the complete model. Confirm the builder and matching serial layout before choosing a system.
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Maytag Neptune laundry uses documented trailing year/month letter systems and repeating-year alternatives. An American-associated Neptune tank is a different product family; its date rule must be chosen explicitly.
Scope matters
Research reviewed October 16, 2026. This independent tool applies published rules and retains unresolved years and model candidates.
Matching legacy Maytag household appliances and documented Maytag-built variants.
Two trailing letters encode year then month. The 24-year cycle requires model/era context; legacy serials continued after Whirlpool acquired Maytag. Do not truncate at 2006 or apply to earlier independent brands just because ownership later changed.
Water heaters only after confirmation of this manufacturer, product family, date-code layout and documented era.
YYWW: first two digits year; next two production week. The 2024 manufacturer guide permits week 53. No model, capacity, fuel or installation date is encoded by these four digits. 2008 is a conservative supported-range limit, not an asserted universal changeover. The October 2016 SAP change uses a 13-character printed date-plus-serial. A bare nine-digit barcode/SAP serial has NO date code and is deliberately not decoded. The supplied historical inspection chart lists additional names, but that relationship does not prove the manufacturer of every product bearing the same brand. This option requires independent confirmation from the unit label or model-specific documentation.
Confirm that this is a water heater and that its rating plate or model-specific manufacturer documentation uses this exact numbering family. A historical brand list or a matching serial shape alone is insufficient.
Historical 2010 TIJ chart’s American/Craftmaster/Mor-Flo/private-label list only, with explicit water-heater/manufacturer confirmation.
This is secondary-chart evidence, not a currently manufacturer-verified universal rule. The supplied anonymized 9746******means year ending 97/week 46 in its 1997 worked context.2010 is a conservative reviewed-publication horizon, not a claim the system endedthen. The chart’s American acquisition year 2001 is wrong; ownership history must not establish a serial-era cutoff.
Select only after confirming the water heater or boiler family and numbering system described here. Brand ownership alone does not establish this system.
Reading your result
Some systems reuse letters or only encode the last one or two year digits. Every supported interpretation is retained. A decade supplied from reliable records can narrow the reading; the tool does not automatically pick the newest year.
Usually the model is a separate plate field. Where published serial ranges actually identify a model, the result shows model candidates and links to their manuals. Overlapping ranges remain ambiguous.
After a lookup, the address includes the serial in a fragment beginning with #serial=. Use “Copy share link” to share the serial and selected context. Opening the link runs the same lookup. The fragment is not a query-string result page.