Ducane serial number lookup: age of a furnace, AC or heat pump
The serial number is on the data plate of the unit. In a current Ducane serial the third and fourth digits are the year and the letter after them is the month. Older all-digit serials end with the year and the week.
Decode a Ducane serial number
How to read a Ducane serial number
Ducane has used 2 serial formats. Find the one that matches the shape of your serial.
Plant code, year, month letter
The first two digits are the plant. The third and fourth digits are the year. The letter after them is the month, A for January through M for December with the letter I left out.
Shape: four digits, a letter and five digits.
1611A12345 reads as January 2011.
Month letter
- A January
- B February
- C March
- D April
- E May
- F June
- G July
- H August
- J September
- K October
- L November
- M December
Plant codes: 16 Orangeburg, 46 Blackville, 56 Stuttgart, 58 and 59 Marshalltown, 60 Grenada, 84 Bellevue, 17 and 19 Saltillo.
Year and week, last four digits
The serial is all digits. The seventh and eighth digits are the year and the last two digits are the week.
Shape: ten digits with no letters.
0183290431 reads as week 31 of 2004 (around August).
Allied Air calls these “old style units” without giving dates. The documented examples run from 1999 to 2004.
Where to find the serial number
The serial number is on the data plate of the unit.
If the serial number does not decode
- Ducane equipment is built by Allied Air Enterprises, a Lennox International company.
- When the installation date cannot be verified, Allied Air counts warranty from 90 days after the manufacture date in the serial.
- Gas furnaces from the 1980s and 1990s print the year of the safety standard they were certified to, for example “Z21.47” followed by a year. The furnace was built in that year or a few years after it.
What the age tells you
| Equipment | Typical service life |
|---|---|
| Furnace | 15 to 22 years |
| Central air conditioner | 10 to 21 years |
| Heat pump | 15 to 16 years |
About Ducane
The Ducane Company of Columbia, South Carolina built oil furnaces that were also sold under many other brand names. Ducane is now a brand of Allied Air Enterprises, a Lennox International company.
Brands that share this serial system: Armstrong Air, Lennox.
Questions and answers
Which characters in a Ducane serial number show the date?
The first two digits are the plant. The third and fourth digits are the year. The letter after them is the month, A for January through M for December with the letter I left out. This applies to units built since January 1993.
Why does my Ducane serial number look different?
Ducane has used 2 serial formats: plant code, year, month letter (built since January 1993); year and week, last four digits (built until the mid-2000s). The decoder tries each one.
Who makes Ducane heating and cooling equipment?
Ducane equipment is built by Allied Air Enterprises, a Lennox International company.
Sources
- Allied Air Enterprises: Warranty Procedures WP20595203, revision 10 (2015), serial number section (manufacturer): https://s7d2.scene7.com/is/content/AlliedAirEnterprises/Warranty%20Documents/Warranty%20Library_2015%20Warranty%20Procedures%20Rev%2010.pdf
- Building Intelligence Center: Armstrong Air HVAC age (independent reference): https://www.building-center.org/armstrong-hvac-age/
- Building Intelligence Center: Ducane HVAC age (independent reference): https://www.building-center.org/ducane-hvac-age/
- Allied Air Enterprises: warranty lookup (manufacturer): https://apps.alliedconnect.com/WarrantyPeriodLookup/ExtendedWarrantyLookup.aspx?Alias=ALD&USERSORG=AR01
Formats last checked against these sources on October 5, 2026. Found a serial that does not fit? Send a correction. How formats are verified: method and sources.