Rheem Serial Number Lookup
Find out exactly how old your Rheem 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 Rheem in seconds
Rheem and Ruud are the same company and share a distinctive month-letter serial code. The 4th–7th digits also spell the week and year on newer units.
Rheem 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 |
|---|---|---|
| Modern | Digits 3–6 = WWYY week & year on many units | …1423… → week 14, 2023 |
| Classic | 1st char = month letter (A–M, skip I), 2nd = year last digit | K4… → Oct, 2014/2024 |
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 Rheem model number (size)
Almost every HVAC brand hides the tonnage in the model number as a 2–3 digit BTU code. RA1436AJ1NA → RA14 = 14-SEER AC · 36 = 3-ton
| 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 Rheem unit?
Can I just replace the Rheem 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 Rheem? 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