HVAC Model Number Tonnage Decoder
Instant HVAC model number decoder. Enter the model string on your Carrier, Trane, Goodman, Lennox, Rheem, or York nameplate to find its tonnage and BTU rating.
🔍 How to Locate Your HVAC Rating Nameplate
HVAC equipment data plates are aluminum or weather-resistant vinyl stickers located in specific standard locations.
Look on the rear or side corner above the refrigerant service valves, or directly behind the electrical disconnect panel. The model number (M/N) and serial number (S/N) are stamped at the top of the metal foil plate.
Remove the upper front access panel or inspect the left/right outer casing of the furnace or air handler blower compartment. Evaporator cased coils have their own separate data plate on the front delta plate.
ACCA Manual J / Manual S Thermal Load & Sizing Hierarchy
Building envelope sensible heat gains, solar radiation, and latent occupant loads mapped to nominal equipment capacity.
HVAC Model Number Capacity Conversion Equation
| Symbol | Variable | Description | Standard Units |
|---|---|---|---|
Capacity_Digits | Model Capacity Code | Two-digit nominal BTU number stamped into the model sequence (e.g., 36 = 36,000 BTU) | kBTU/hr |
12 | BTU to Ton Factor | Number of thousands of BTUs per refrigeration ton (12,000 BTU/hr per ton) | Constant |
Tonnage | Nominal Cooling Tons | Rated equipment refrigeration capacity under AHRI 95°F outdoor test conditions | Tons |
Airflow_CFM | Standard Blower Airflow | ACCA standard 400 CFM per nominal cooling ton | CFM |
How to Read Serial Numbers for Age & Manufacture Date
HVAC serial numbers encode the exact year and calendar week of factory production. For example:
- Carrier / Bryant: First 2 digits = Week, 3rd & 4th digits = Year (e.g.
3218E12345= 32nd week of 2018). - Goodman / Amana: First 2 digits = Year, 3rd & 4th digits = Month (e.g.
1805123456= May 2018). - Trane / American Standard: First 2 digits = Year, followed by week (e.g.
19324M234F= 2019). - Rheem / Ruud: Plant letter followed by 2 digits week and 2 digits year (e.g.
W341912345= Week 34 of 2019).
| Model Digits | Nominal Tonnage | Cooling Capacity (BTU/hr) | Recommended Airflow (CFM) | Typical Home Size (Sq Ft) |
|---|---|---|---|---|
18 / 018 | 1.5 Tons | 18,000 BTU/hr | 600 CFM | 600 – 900 sq ft |
24 / 024 | 2.0 Tons | 24,000 BTU/hr | 800 CFM | 900 – 1,300 sq ft |
30 / 030 | 2.5 Tons | 30,000 BTU/hr | 1,000 CFM | 1,300 – 1,650 sq ft |
36 / 036 | 3.0 Tons | 36,000 BTU/hr | 1,200 CFM | 1,650 – 2,100 sq ft |
42 / 042 | 3.5 Tons | 42,000 BTU/hr | 1,400 CFM | 2,100 – 2,500 sq ft |
48 / 048 | 4.0 Tons | 48,000 BTU/hr | 1,600 CFM | 2,500 – 3,000 sq ft |
60 / 060 | 5.0 Tons | 60,000 BTU/hr | 2,000 CFM | 3,000 – 3,800 sq ft |
Scenario: A technician inspects a weather-worn outdoor condenser stamped with Model Number GSX140361KB and Serial Number 1805123456.
Step-by-Step Decoding Breakdown:
- Brand Identification: Prefix
GSXidentifies a Goodman 14-SEER residential split system condenser. - Tonnage Extraction: Digits
036represent 36,000 BTU/hr (36,000 / 12,000 = 3.0 Tons nominal cooling capacity). - Airflow Requirement: 3.0 Tons × 400 CFM/ton = 1,200 CFM required duct blower airflow.
- Manufacturing Age: Serial number
1805...indicates manufacture in May 2018.
Frequently Asked Questions
Where do I find the model number on my air conditioner?
How do I tell the tonnage from an AC model number?
Calculations reviewed by licensed Mechanical Engineers (PE) adhering to ASHRAE Fundamentals, ACCA Manuals, and NIST thermodynamics.