To determine the extractor fan size, multiply grow room volume (cubic feet) by the carbon filter factor (+25%), insulation factor (±20%), ducting (+10% for 10 feet), and light factor (+10% for 1000W). This gives the fan size in CFM.
For a 10×10 room with 8 foot ceilings, the cubic footage is 800 cf. A 160 CFM exhaust fan removes the air every 5 minutes.
Exhaust fans remove humidity and excess heat. Properly sizing the exhaust fan capacity to the grow room is important for ventilation. Fans are measured in CFM – cubic feet per minute of air moved.
Match the CFM rating to the size of the tent or room to ensure sufficient air exchange. Quiet operation allows using fans in living spaces. Install at the top and intake vents at bottom to improve efficiency. Following size guidelines avoids calculations.
Room Ventilation Tips
- Install fan at the top and intake vents at bottom for better efficiency.
- Match the CFM rating to the size of the tent or room for sufficient air exchange.
- Quiet operation allows fans to be used in living spaces.
Fan Sizing Examples
- For a 4×4 tent with ~106 cubic feet, a 215 CFM fan works well.
- Fans should run 24/7 during the late flowering stage.
- An ideal 6 inch 400 CFM inline fan is suitable for a 5×5 tent.
To determine CFM, multiply tent volume by factors like carbon filter (+25%), insulation (±20%), ducting (+10%), and lights (+10%). An 8x8x7 tent in a basement needs around a 1500 CFM fan.
Consider grow room volume, carbon filters, insulation, ducting, and lights when calculating CFM. Exchange air every 3 minutes. Following size guidelines avoids complicated calculations.