Cooling Coil Face Velocity and Carryover Check
Face velocity = CFM / coil face area, checked against the ~500 fpm wet-coil carryover limit.
Example
You enter
- Airflow (cfm) 2000
- Coil face width (in) 24
- Coil face height (in) 18
- Carryover threshold (fpm, default 500) 500
You get
- Face area 3 ft^2
- Face velocity 667
No published worked example is on file for this calculation. It is checked against a hand-worked derivation of its method and an independent reference test.
Details, formula, and sources
Scope2000 CFM on a 24x18 coil (3.0 ft^2) -> 667 fpm, carryover risk; 1200 CFM -> 400 fpm, safe. Above the limit a wet coil blows condensate past the drain pan. The coil manufacturer's rated face velocity governs.
Formula or tableface_area = w x h / 144; face_velocity = CFM / face_area; carryover if velocity > threshold (~500 fpm).
Source and editionThe cooling-coil face velocity and the moisture-carryover limit, standard coil-selection practice (ASHRAE), by name.
Free accessFace velocity = airflow / face area and the ~500 fpm wet-coil carryover limit are standard published coil-selection results.
What governsEstimate. AHJ and licensed professional govern.
API field namescfm, face_width_in, face_height_in, threshold_fpm, face_area_ft2, face_velocity_fpm
- Face velocity CFM / (width x height / 144)coil-selection practice
- Carryover limit ~500 fpm for a wet cooling coil (editable)ASHRAE / coil practice
- Selection aid the coil manufacturer's rated face velocity governsscope of this tile