Airflow, Ventilation & CO₂
Exhaust Fan
An exhaust fan is a device that pulls warm, stale air out of a grow space to maintain proper temperature, humidity, and air quality.
What an Exhaust Fan Does in a Grow Space
In cannabis cultivation, an exhaust fan is a critical component of the ventilation system responsible for removing used air from a grow room or tent. By expelling hot, humid, and CO₂-depleted air, exhaust fans help create a stable and healthy environment for plant growth.
Why Exhaust Fans Became Essential for Indoor Growing
Historically, as growers transitioned from outdoor cultivation to enclosed indoor spaces, the need for controlled air exchange became obvious. Early indoor grows suffered from heat buildup and poor air quality until exhaust systems were adopted. With the expansion of commercial cannabis facilities, exhaust fans became standard equipment, engineered specifically for horticultural airflow demands.
How Exhaust Fans Create Air Exchange
Exhaust fans work by creating negative pressure (slightly lower air pressure inside the grow space than outside). This pressure difference pulls fresh air in through intake vents while pushing stale air out through the exhaust. This continuous exchange supports photosynthesis by replenishing carbon dioxide and prevents excess heat from high-intensity lighting.
Managing Temperature, Humidity, and Odors
In cannabis cultivation, exhaust fans play a major role in temperature and humidity control. Without adequate exhaust, heat stress can slow growth, reduce yields, and damage terpenes. High humidity caused by poor air removal increases the risk of mold and bud rot, especially during flowering. Exhaust fans are often paired with carbon filters to remove odors before air is released outside
Choosing the Right Fan Size and Airflow
Fan size and power must match the grow space volume and lighting output. Fans are typically rated in CFM (cubic feet per minute), which indicates how much air they can move. Growers calculate required CFM based on room size and heat load to ensure efficient air exchange.
Common Exhaust Fan Problems and Best Practices
Common challenges include undersized fans, excessive noise, vibration, and improper ducting. Best practices include using insulated ducting, proper fan speed control, and regular maintenance.
Related terms:
Ventilation, Airflow, Carbon Filter, Humidity Control, Temperature, and Indoor Cultivation.
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