Move air, scrub odor and hold the room on target. Inline and circulation fans, carbon filters and pre-filters, intake filtration, ducting with every connector, clamp and damper, dehumidifiers and humidifiers, CO2 and climate controllers.
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The exhaust line
Most rooms are built around one exhaust line: a Carbon Filters & Odor Control inside the room, an inline fan pulling air through it, and ducting carrying that air outside. Inline Fans are sized in inches and rated in cubic feet per minute (CFM). Match the fan, the filter and the Ducting to the same diameter, and join them with Duct Connectors & Reducers and Clamps, Dampers & Light Traps so the line is airtight and light tight.
Sizing a fan
Work out the volume of the room in cubic feet (length by width by height). A fan should be able to exchange that volume in one to three minutes. Then add capacity for every restriction in the line: a carbon filter, long or bent ducting and hot lights all reduce real airflow, so most growers size up by 25 to 50 percent and run the fan on a speed controller.
Air coming in and moving around
Air that leaves has to be replaced. Intake Filters & Bug Nets keep dust, spores and insects out of the incoming air. Inside the room, Circulation & Exhaust Fans keep air moving across the canopy, which strengthens stems and prevents the humid pockets where mold starts.
Humidity, CO2 and control
Dehumidifiers & Humidifiers hold humidity on target at each stage. {L:co2} raises carbon dioxide in sealed and semi sealed rooms. Climate & Fan Controllers tie it together, switching and slowing equipment by temperature so the room holds steady without constant attention.
Grow Room Ventilation & Climate Control FAQ
What size inline fan do I need?
Calculate room volume in cubic feet and choose a fan whose CFM rating exchanges that volume every one to three minutes, then size up 25 to 50 percent to cover the carbon filter and ducting.
Does the carbon filter go inside or outside the room?
Inside, at the start of the exhaust line and as high as practical, so the fan pulls room air through the filter before it leaves.
Should the fan push or pull through the filter?
Pull. Filters are designed for air to be drawn through the carbon bed from the outside in.
How do I stop light leaks through vents?
Use light proof ducting for short runs and a light trap on passive vents. Both pass air while blocking light.
Do I need a dehumidifier?
In flowering rooms and sealed rooms, usually yes. Plants release most of the water they take up, and ventilation alone often cannot keep up late in flower.
