Lennox HVAC Age by Serial Number
Enter the serial number from your Lennox furnace, AC or heat pump's data plate to get its manufacture date, remaining life, warranty and recall status, and a repair-or-replace recommendation.
How to read a Lennox serial number
We can decode serial numbers from Lennox furnaces, ACs and heat pumps built 1990–2026.
2008–2026 format
Lennox serial numbers have four digits, a letter, then five (sometimes six) more digits. The first two digits are the factory, the next two are the year and the letter is the month, so a serial starting 5809C was made in March 2009. Month letters run A = January, B = February, C = March and on through the alphabet.
2008–2026 format Corroborated
For units made from September to December, the month letter is J (September), K (October), L (November) or M (December). Lennox skips the letter I, so a serial starting 5819K was made in October 2019.
This format is confirmed by two or more independent references rather than a Lennox document for this product line, so treat dates from it as likely rather than certain.
1990–2007 format Corroborated
Older Lennox units (1990 to 2007) with a four-digit, one-letter, five-digit serial use the same layout: digits three and four are the year and the letter is the month (A = January to M = December, no I), so 5896A36571 was made in January 1996. This reading is less certain than for newer units.
This format is confirmed by two or more independent references rather than a Lennox document for this product line, so treat dates from it as likely rather than certain.
Worked examples
year month / week
| Serial | Built |
|---|---|
| 1909C05716 | March 2009 |
| 5809C05716 | March 2009 |
| 5921C05716 | March 2021 |
| 5921CO05716 | March 2021 |
| 5609H00001 | August 2009 |
| 5610M99999 | December 2010 |
| 5621M99989 | December 2021 |
| 5604G00001 | July 2004 |
Where to find the data plate on a furnace, AC or heat pump →
How long does a Lennox furnace, AC or heat pump last?
| Type | Typical life |
|---|---|
| Heat pump | 10–16 years |
| Gas furnace | 15–25 years |
| Central AC | 10–15 years |
Ranges come from industry life-expectancy studies (NAHB/Bank of America, InterNACHI, DOE) and apply across brands. Your result adjusts for your state's climate.
Is my Lennox furnace, AC or heat pump still under warranty?
- Furnaces: Merit and Elite furnaces: 5-year parts warranty, 10 years if registered within 60 days. Dave Lennox Signature Collection: 10 years, 12 if registered. Heat exchangers are covered for 20 years, or for life for the original owner on most Elite and Signature 90%+ furnaces.
- Air conditioners: Merit and Elite air conditioners: 5-year parts warranty, 10 years if registered within 60 days. Compressors are covered 10 years on Elite and Signature models; Merit compressors get 5 years, or 10 if registered. Signature models get 10 years on parts, 12 if registered.
- Heat pumps: Merit and Elite heat pumps: 5-year parts warranty, 10 years if registered within 60 days. Compressors are covered 10 years on Elite and Signature models; Merit compressors get 5 years, or 10 if registered. Signature models get 10 years on parts, 12 if registered.
Register within 60 days of installation (or the closing date for a new home) to extend parts coverage from 5 to 10 years on Merit and Elite models, or from 10 to 12 years on Dave Lennox Signature Collection models. In California, Florida, Georgia (installed 2026 or later) and Quebec the extension is automatic.
Lennox furnace, AC or heat pump recalls
Recalls come from the U.S. Consumer Product Safety Commission. Decode your unit above to check whether its model and serial fall inside a recall.
Should you repair or replace it?
Once you decode your unit, we compare its age against its typical life, a typical major repair against the cost of replacing it, and, with your model and state, what a new unit would save on energy. A common rule of thumb: if a repair costs more than about 30–50% of a replacement and the unit is past mid-life, replacing usually wins.
FAQ
How do I tell how old my Lennox furnace, AC or heat pump is?
The manufacture date is encoded in the serial number on the unit's data plate. Lennox serial numbers have four digits, a letter, then five (sometimes six) more digits. The first two digits are the factory, the next two are the year and the letter is the month, so a serial starting 5809C was made in March 2009. Month letters run A = January, B = February, C = March and on through the alphabet. For units made from September to December, the month letter is J (September), K (October), L (November) or M (December). Lennox skips the letter I, so a serial starting 5819K was made in October 2019. Older Lennox units (1990 to 2007) with a four-digit, one-letter, five-digit serial use the same layout: digits three and four are the year and the letter is the month (A = January to M = December, no I), so 5896A36571 was made in January 1996. This reading is less certain than for newer units. We can decode Lennox furnaces, ACs and heat pumps built 1990–2026. Enter the serial above to decode it automatically.
How long does a Lennox furnace, AC or heat pump last?
Typical lifespans: Heat pump 10–16 years; Gas furnace 15–25 years; Central AC 10–15 years. These ranges apply across brands. Maintenance, climate and water hardness move a unit toward one end.
How do I check my Lennox warranty?
Register within 60 days of installation (or the closing date for a new home) to extend parts coverage from 5 to 10 years on Merit and Elite models, or from 10 to 12 years on Dave Lennox Signature Collection models. In California, Florida, Georgia (installed 2026 or later) and Quebec the extension is automatic. Lennox's warranty lookup: https://www.lennox.com/residential/owners/assistance/warranty/ Register a unit: https://www.warrantyyourway.com/
Has my Lennox furnace, AC or heat pump been recalled?
The U.S. Consumer Product Safety Commission lists 1 recall for Lennox furnaces, ACs and heat pumps. Enter your model and serial above to check yours against each recall's scope.
Sources: Lennox service, warranty and installation documentation; independent industry references for formats no Lennox document covers; U.S. Consumer Product Safety Commission; DOE and ENERGY STAR; NAHB/Bank of America and InterNACHI life-expectancy studies. More about our sources.