HVAC Model Number Tonnage Decoder
Decode supported manufacturer model-number patterns (Carrier, Trane, Lennox, Goodman, Rheem, Daikin) to identify nominal tonnage, BTU capacity, and series.
Interactive Calculator & Visualizer
đ 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.
Engineering Methodology & Governing Equations
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.
How to Find AC Tonnage by Model Number
Air conditioner and heat pump data plates contain encoded engineering specifications. The model number indicates the equipment design series, nominal refrigeration capacity, and SEER efficiency tier. The serial number identifies the specific manufacturing date and production plant.
- Locate the Equipment Rating Plate: Find the metal data plate attached to the outdoor condenser cabinet or the indoor air handler/furnace access panel labeled "Model No.", "M/N", or "Product No.".
- Distinguish Model Number vs. Serial Number:
- Model Number (M/N): Identifies the unit type and capacity rating (e.g.,
24ACC636A003,4TTR4036L1000AA,GSX140361KB). - Serial Number (S/N): Identifies the date and plant of assembly (e.g.,
3218E12345= Week 32, 2018).
- Model Number (M/N): Identifies the unit type and capacity rating (e.g.,
- Identify the Embedded Capacity Digits: Scan the middle portion of the model number for a two- or three-digit number representing nominal thousands of BTU/hr (e.g.,
024,036,048). - Divide Capacity Digits by 12: Because 1 ton of refrigeration equals 12,000 BTU/hr, dividing the capacity number by 12 yields nominal cooling tonnage (e.g.,
36 / 12 = 3.0 Tons). - Evaluate Standard Design Airflow: Standard residential air conditioning operates at 400 CFM per nominal ton under ACCA and ASHRAE design standards (e.g., 3.0 Tons = 1,200 CFM).
HVAC Model Number Capacity Conversion Equations
| Symbol | Variable | Description | Standard Units |
|---|---|---|---|
\text{Capacity Digits} | Model Capacity Code | Nominal BTU digits embedded in the model sequence (e.g., 36 = 36,000 BTU/hr) | kBTU/hr |
12 | BTU to Ton Constant | Standard refrigeration conversion constant (12,000 BTU/hr per cooling ton) | Constant |
\text{Nominal Tonnage} | Rated Cooling Capacity | Equipment nominal capacity under standard AHRI 210/240 rating conditions | Tons |
\text{Design Airflow}_{\text{CFM}} | Standard Blower Airflow | Standard evaporator airflow volume across cooling coil (400 CFM/ton) | CFM |
Manufacturer Model Number Nomenclature Reference
How leading HVAC manufacturers encode nominal cooling capacity into residential model numbers:
- Carrier / Bryant / Payne: Digits following the alpha series code represent nominal BTU (e.g.,
24ACC636...$\rightarrow$36= 3.0 Tons / 36,000 BTU/hr). - Trane / American Standard: Digits 6â8 contain the capacity code (e.g.,
4TTR4036...$\rightarrow$036= 3.0 Tons / 36,000 BTU/hr). Prefix4TTindicates R-410A cooling;4TWindicates R-410A heat pump. - Goodman / Amana / Daikin: Digits 5â7 following the SEER tier indicate capacity (e.g.,
GSX14036...$\rightarrow$036= 3.0 Tons / 36,000 BTU/hr;14= 14 SEER). - Lennox: 3-digit capacity code typically separated by dashes (e.g.,
14ACX-036-230$\rightarrow$036= 3.0 Tons / 36,000 BTU/hr). - Rheem / Ruud: Digits 5â6 contain capacity (e.g.,
RA1636...$\rightarrow$36= 3.0 Tons / 36,000 BTU/hr;16= 16 SEER). - ICP / Heil / Tempstar: Digits following model prefix (e.g.,
NXA636...$\rightarrow$36= 3.0 Tons / 36,000 BTU/hr). - York / Coleman / Luxaire: Digits following series code (e.g.,
YCG36...$\rightarrow$36= 3.0 Tons / 36,000 BTU/hr).
Next Steps: Sizing & Load Verification Workflows
âĸ Verify Existing Equipment Sizing: AC Tonnage & Room Sizer â check whether your decoded tonnage matches conditioned home square footage and regional climate demands.
âĸ Calculate Heat Gain Loads: BTU Heating & Cooling Load Calculator â perform whole-home Manual J load estimations for replacement equipment sizing.
âĸ Explore Cooling Pillar: Cooling Loads, AC Tonnage & Sizing Hub â access the full suite of cooling calculation tools.
Standard Engineering Reference Matrix
AC Model Number Capacity & Tonnage Reference Matrix
Standard nominal model capacity codes, equivalent cooling BTU/hr, recommended design blower airflow, and typical residential square footage coverage:
| Model Capacity Code | Nominal Tonnage | Cooling Capacity (BTU/hr) | Design Blower Airflow (CFM) | Typical Conditioned Floor Area |
|---|---|---|---|---|
18 / 018 | 1.5 Tons | 18,000 BTU/hr | 600 CFM | 600 â 900 sq ft |
24 / 024 | 2.0 Tons | 24,000 BTU/hr | 800 CFM | 900 â 1,300 sq ft |
30 / 030 | 2.5 Tons | 30,000 BTU/hr | 1,000 CFM | 1,300 â 1,650 sq ft |
36 / 036 | 3.0 Tons | 36,000 BTU/hr | 1,200 CFM | 1,650 â 2,100 sq ft |
42 / 042 | 3.5 Tons | 42,000 BTU/hr | 1,400 CFM | 2,100 â 2,500 sq ft |
48 / 048 | 4.0 Tons | 48,000 BTU/hr | 1,600 CFM | 2,500 â 3,000 sq ft |
60 / 060 | 5.0 Tons | 60,000 BTU/hr | 2,000 CFM | 3,000 â 3,800 sq ft |
Worked Engineering Sizing Example
Worked Example 1: Decoding a Carrier 3-Ton Split AC Condenser
Scenario: A technician inspects a Carrier data plate stamped with Model Number 24ACC636A003 and Serial Number 3218E12345.
Step 1: Identify Brand Prefix & Equipment Type
Prefix '24' = Carrier air conditioning condenser | Digit '6' in 24ACC6 = 16 SEER nominal efficiency tier
Step 2: Extract Nominal Capacity Digits
Capacity Digits '36' = 36,000 BTU/hr ==> 36,000 / 12,000 = 3.0 Tons nominal cooling
Step 3: Decode Manufacture Date from Serial Number
Serial '3218...' = Week 32 of 2018 | Design Blower Airflow = 3.0 Tons * 400 CFM/ton = 1,200 CFM
â Result: 3.0 Ton (36,000 BTU/hr) 16-SEER condenser manufactured in August 2018. Connect to the AC Tonnage Sizer to check home square footage coverage.
Worked Example 2: Decoding a Trane 3-Ton Heat Pump Condenser
Scenario: A data tag on an outdoor Trane unit reads Model Number 4TTR4036L1000AA and Serial Number 19324M234F.
Step 1: Identify Refrigerant & Series
Prefix '4TT' = Trane R-410A air conditioner | Digit '4' = 14 SEER series
Step 2: Extract Capacity Digits
Digits '036' = 36,000 BTU/hr ==> 36,000 / 12,000 = 3.0 Tons nominal capacity
Step 3: Decode Manufacture Year
Serial '1932...' = Manufactured in 2019 (Week 32) | Required Airflow = 1,200 CFM
â Result: 3.0 Ton Trane R-410A condenser manufactured in 2019. Cross-check cooling load requirements using the BTU Load Calculator.
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?
Calculation engines undergo software-level verification against documented equations, reference values, boundary conditions, and automated tests referencing ASHRAE, ACCA, SMACNA, and NIST publications.
âī¸ Engineering Reference & Regulatory Disclaimers
Engineering Reference Notice: HVACLogic.org is an independent computational reference and engineering design aid authored by Miad S. Calculations are based on consensus engineering formulations (including ASHRAE, ACCA, and SMACNA publications) and are intended solely for preliminary estimation, parametric analysis, and educational use. HVACLogic does not provide licensed professional engineering services, structural evaluations, or legally binding code determinations.
Professional Review & Permitting Notice: Where the applicable jurisdiction, project type, occupancy classification, permit process, or professional-practice law requires licensed professional review, certification, or a sealed/stamped calculation, the user must obtain that review from an appropriately licensed Professional Engineer (PE) or qualified mechanical contractor. Where a jurisdiction or Authority Having Jurisdiction (AHJ) requires specific calculation software, documentation, or permit submittal forms, users must follow the applicable local requirements.
Manufacturer Data Notice: Generic engineering formulas provide baseline theoretical approximations. Actual equipment performance, expanded cooling/heating capacities at specific outdoor temperatures, sensible-to-total heat ratios, fan airflow curves, and electrical characteristics (MCA/MOP) must be verified against manufacturer technical product data specifications.