Lennox Serial Number Lookup
Find out exactly how old your Lennox furnace, air conditioner, or heat pump is — and what size it is — in about 30 seconds. Then see what it costs to replace it factory-direct.
Decode your Lennox in seconds
Lennox serial numbers are the trickiest in the industry — the format has changed repeatedly and isn't always reliable. The most dependable answer is the MFG DATE printed in plain text on the rating plate.
Lennox serials are unreliable — look for the plain-text “Manufactured MM/YYYY” field on the metal rating plate. Snap a photo and text it to us at (888) 762-1334 and we'll confirm the age and the right replacement.
Lennox serial number formats by era
HVAC makers change their date codes over the years. Match the start of your serial to the right row.
| Era | How the date is coded | Example |
|---|---|---|
| Most units | Look for a plain-text “Manufactured 03/2019” / MFG DATE field on the nameplate | 03/2019 → March 2019 |
| Many residential | First 4 digits = plant + year (e.g. 5804 = 2004 plant 58) | 5804J12345 → 2004 |
Where to find the serial & model number
A metal or foil label on the side of the outdoor condenser or inside the furnace cabinet door.
Use the format table above to turn it into a manufacture date.
The model number tells you the size — see the tonnage guide below.
Over ~12–15 years old? Replacing usually beats repairing. We can price it.
Reading the Lennox model number (size)
Almost every HVAC brand hides the tonnage in the model number as a 2–3 digit BTU code. XC16-036-230 → XC16 = 16-SEER AC · 036 = 3-ton · 230 = voltage
| Model code | Size | Cooling capacity |
|---|---|---|
| 018 | 1.5 ton | 18,000 BTU |
| 024 | 2 ton | 24,000 BTU |
| 030 | 2.5 ton | 30,000 BTU |
| 036 | 3 ton | 36,000 BTU |
| 042 | 3.5 ton | 42,000 BTU |
| 048 | 4 ton | 48,000 BTU |
| 060 | 5 ton | 60,000 BTU |
1 ton = 12,000 BTU/hr. Gas furnaces instead show input BTUs (e.g. 060 = 60,000 BTU input).
Frequently asked questions
How old is too old for a Lennox unit?
Can I just replace the Lennox unit myself and save?
My serial number doesn't match any format above.
Does the model number tell me efficiency too?
Time to replace your Lennox? Skip the markup.
Get the same equipment factory-direct and save 40–60% versus a contractor quote. No salesperson — just a price.
Call (888) 762-1334