For example, split serial number 5807G12345 as 58 | 07 | G | 12345. Plant code 58 identifies the Marshalltown plant, 07 means 2007, G means July, and 12345 identifies the individual unit. The plant code and unit sequence do not influence the manufacture date.
Lennox month letters run from A through M and skip I. Appliage uses this plant, year and month structure for dates from 1970 onward. The Lennox serial number alone is enough to return the manufacture month and an estimated age, so the model number is optional.
Lennox serial numbers beginning with plant code 69 are an exception. In the documented plant-69 group, positions 3–4 still give the year, but the available date record does not identify a month position. Appliage therefore returns the manufacture year without assigning a month that the serial number cannot verify.
Lennox Age Rules
- 1–2 plant code
- 3–4 two digit year
- 5 month letter
- 6 onward unit sequence
Positions 1–2 identify the plant that built the equipment. Positions 3–4 provide the year, and position 5 provides the month. Characters after the month letter identify the individual unit. The plant code tells Lennox where the equipment was made, while the sequence distinguishes that unit from others made at the same plant. Neither field influences the manufacture date.
Lennox Plant Codes
| Plant code | Plant or production group |
|---|---|
| 16 | Orangeburg |
| 46 | Blackville |
| 51 | Columbus |
| 53 | Des Moines |
| 54 | Fort Worth |
| 55 | Heatcraft |
| 56 | Stuttgart/Marshalltown production group |
| 58 | Marshalltown |
| 60 | ADP |
| 63 | Toronto |
| 69 | Documented group made under contract in China; Appliage returns the year only |
| 84 | Armstrong |
A plant code outside this table can still give a year and month if the rest of the serial number matches the Lennox plant, year and month structure.
Lennox Month Codes in Position 5
| Month code | Manufacture month |
|---|---|
| A | January |
| B | February |
| C | March |
| D | April |
| E | May |
| F | June |
| G | July |
| H | August |
| J | September |
| K | October |
| L | November |
| M | December |
Lennox skips the letter I. If position 5 clearly contains I, the serial number does not match this month table.
Lennox Year Codes in Positions 3–4
| Year code | Year used by Appliage |
|---|---|
| 70–99 | 1970–1999 |
| 00–26 | 2000–2026 |
| 27–69 | No current result: the 1900s year is before 1970, when this format begins, and the 2000s year is still in the future |
Lennox Serial Numbers Appliage Cannot Find the Age
A serial number that is too short, does not have year digits in positions 3–4, or has a position-5 letter outside A–H and J–M does not match the main Lennox structure. Appliage returns no manufacture date because the Lennox rule cannot be applied to those positions.
Plant-69 serial numbers are handled separately. When positions 3–4 produce a past year from 1970 onward, Appliage can return that year, but it cannot return a month. Therefore, a result such as 2015 is an estimate of the year only.
Lennox hearth and fireplace products use another numbering system. Their serial numbers cannot be decoded with the HVAC structure on this page. The manufacture date can also differ from the installation date and warranty start date.
Ducane and the Allied Air Brands
Newer Ducane equipment uses the same plant, year, and month order. Ducane also has an older structure of ten digits: the published placement puts the year in positions 7–8 and the production week in positions 9–10. Serial number 0183290431, for example, dates to production week 31 of 2004.
Some Ducane units from the 1980s, before Lennox owned the brand, are reported with the date at the front of the serial instead, so a ten digit serial that fits both placements comes back with both dates. Enter a serial like that on the Ducane serial number lookup, because the decoder on this page covers only the plant, year, and month style.
Armstrong Air, AirEase, and Concord use the Allied Air structure from 1993 onward. Older Armstrong structures use other codes and cannot be decoded with the positions above.
Sources
- Lennox serial number reference. The diagram labels the factory, year and month positions. Archived copy.
- Allied Air and Ducane serial number reference. Allied Air explains both Ducane formats. Archived copy.
- Lennox warranty lookup
- Lennox model and serial number help
- CPSC: Lennox heat pump recall (20-083). The affected serials begin with factory code 69.
- CPSC: Lennox garage heater recall (11-197). The serial range includes the first worked example.
For other brands, see our appliance serial number lookup.
