Armstrong, Ducane, AirEase & Concord Age
Armstrong Air, Ducane, AirEase and Concord are built by Allied Air, part of Lennox. Their serials use a Lennox-style code where characters 3–4 are the year and the 5th is a month letter. Choose your brand and enter the serial.
Part of the hvac age lookup
Serial number age lookup
Four brands from Allied Air
Allied Air Enterprises is Lennox’s second residential manufacturer, selling through independent distributors rather than Lennox’s own dealer network. Its main brands:
| Brand | Notes |
|---|---|
| Armstrong Air | The largest of the group. A long-established Midwestern furnace name, widely installed by independent contractors. |
| Ducane | Value-focused heating and cooling line. Not related to the grill brand. |
| AirEase | Long-standing brand known for oil and gas furnaces, common in the Northeast and Midwest. |
| Concord | Budget line with a smaller distribution footprint. |
Allied Air’s main plant is in Blackville, South Carolina. The brands share designs within each tier, so an Armstrong and an AirEase unit of the same tier often differ mainly in branding.
Where to find the serial number
- Outdoor AC or heat pump: on the side of the cabinet near the electrical panel.
- Furnace: inside the blower compartment. Oil furnaces from AirEase and Armstrong often have the plate inside the burner compartment door.
- Coil or air handler: on the cabinet.
The modern serial is ten characters: four digits, a letter, five digits, such as 4607B12345.
How the Allied Air date code works
| Part | Example (4607B12345) | Meaning |
|---|---|---|
| 1–2 | 46 | Plant code (ignore) |
| 3–4 | 07 | Year (2007) |
| 5 | B | Month letter (February) |
| 6–10 | 12345 | Sequence |
- Year
- Month
- Not part of the date
Worked examples
| Serial | Built |
|---|---|
| 4607B12345 | February 2007 |
| 8412K12345 | October 2012 |
| 5819F54321 | June 2019 |
| 4699M22222 | December 1999 |
Example serials are made up to show the format; they don't belong to real units.
This is the same layout Lennox uses. The most common mistake is reading the first two digits as the year: a serial starting 46 isn’t from 1946.
| Letter | Month | Letter | Month |
|---|---|---|---|
| A | January | G | July |
| B | February | H | August |
| C | March | J | September |
| D | April | K | October |
| E | May | L | November |
| F | June | M | December |
How long Allied Air equipment lasts
| Equipment | Typical life |
|---|---|
| Central air conditioner | 12–17 years |
| Heat pump | 10–15 years |
| Gas furnace | 15–20 years |
| Oil furnace | 15–20 years, with yearly cleaning |
Oil furnaces need a professional cleaning and nozzle and filter change every year. Soot build-up in an oil furnace cuts efficiency and shortens its life faster than almost anything else.
What to do with your result
Under 10 years: register and check the warranty; Allied brands commonly offer longer parts coverage when registered.
10 to 15 years: keep up annual service; compare major repair costs with a new system.
Over 15 years: plan a replacement. If you’re replacing an oil furnace, it’s a good moment to compare a heat pump, which may avoid oil deliveries altogether.
Frequently asked questions
How do I read an Armstrong Air serial number?
Skip the first two digits (the plant). The 3rd and 4th digits are the year and the letter after them is the month, A for January through M for December, skipping I. 4607B12345 was built in February 2007.
Who makes Armstrong Air, Ducane and AirEase?
Allied Air Enterprises, a subsidiary of Lennox International, based in South Carolina. Concord and Allied-branded equipment come from the same company.
Is a Ducane furnace related to Ducane grills?
Only by name. Ducane heating and cooling equipment is an Allied Air brand; the Ducane gas grills were a separate business.
Does this work for older Armstrong furnaces?
For units built from about 1993 onward. Older Armstrong and other Allied equipment used week-based and letter codes this decoder doesn't read yet. Check the label for a printed date.
Sources and accuracy
The Allied Air: Armstrong / Ducane / AirEase / Concord decoder is built from these references and cross-checked between them. Facts are restated in our own words; any mistakes are ours.
Status: being verified against real data plates. Rules last reviewed 2026-10-18; page updated 2026-11-07. Not affiliated with Allied Air: Armstrong / Ducane / AirEase / Concord. Report a wrong result.
Part of the hvac age lookup
This page covers one brand. For all furnace, air conditioner and heat pump brands, go to the hvac age lookup.