Airflow · Tonnage
How many CFM for a 2 ton AC?
A 2 ton system needs about 800 CFM at the standard 400 CFM per ton — and a 14-inch trunk to carry it. In a humid climate design for 700 CFM, in a dry one up to 900.
Airflow by climate
| Design point | Airflow | Round duct | Velocity |
|---|---|---|---|
| Humid · 350 CFM/ton | 700 CFM | 14 in | 655 fpm |
| Standard · 400 CFM/ton | 800 CFM | 14 in | 748 fpm |
| Dry · 450 CFM/ton | 900 CFM | 14 in | 842 fpm |
Duct sizes at the standard 0.10 in/100 ft friction rate — size the exact run with the ductulator, and remember the return carries the same air.
FAQ
- How many CFM is a 2 ton unit?
- About 800 CFM at the standard design airflow of 400 CFM per ton. Humid climates design closer to 350 CFM per ton (700 CFM) so the coil runs colder and pulls more moisture; dry climates go up to 450 (900 CFM) for more sensible cooling.
- What duct size carries 800 CFM?
- A 14-inch round trunk at the standard 0.10 in/100 ft friction rate, with air moving at 748 fpm. On a long or noise-sensitive run, design at 0.05 and step up a size.
- How many BTU is 2 tons?
- 24,000 BTU/h, since one ton of refrigeration equals exactly 12,000 BTU/h — about 7 kW of cooling.
- What happens if airflow is below that?
- The evaporator coil runs colder than designed: capacity drops, the coil can ice up, and the compressor sees liquid return. Chronically low airflow almost always traces back to undersized ducts or a restricted return, not to the equipment.
Other sizes: 1.5 ton · 2.5 ton · CFM per ton · what tonnage you need