I am setting up a 7kw flowering room for a medical grow and would like some feedback on the ventilation design. The climate in the area is moderate, average temps range from highs of 50 in the winter to no higher than 80 in the summer months. And because I am a bit shy on power in this space, I want to try and avoid an A/C unit all together and just go with passive air cooling.
The room is basically broken down into three distinct environments:
1. The lighting stack (7x1KW HPS lamps in series, 8" air cooled hoods)
2. The flowering area (three 5x10 tents and one 5x5 tent)
3. The overall room (3500 cubic feet, taking into account the volume of the flowering tents)
I'll go through each area and outline what I have planned for passive temperature control, and I would love feedback on how well ya'll think this will work.
Area #1: The lighting stack. (7x1KW HPS lamps in series, 8" air cooled hoods)
This is a passively cooled string of lamps with a fresh ambient air intake and exhaust, so that the airflow is completely separate from the rest of the room.
An 800cfm fan will draw cool outside air through the reflectors, and then exhaust it back outdoors once it has passed over the lamps.
No carbon filter is needed since the intake is outside of the room, so the 800cfm fan will run pretty much full blast.
I estimate that after duct losses, there will be 500cfm flowing over the lights, which comes to about 5 seconds per air change through the stack (12 per minute / 720 per hour). Is that enough? Too much?
Area #2: The Flowering Tents. (three 5x10 tents and one 5x5 tent)
These tents have circulation fans inside, and a ducted exhaust fan pulling out of the top of the tents and venting into the larger room area.
The exhaust fans are currently sized to provide about 20 air changes per hour through each tent. Is that enough? Too much?
The exhaust fan will pull cool air in through the passive intakes in the bottom of each tent.
Area #3: The Overall Room. (3500 cubic feet, taking into account the volume of the flowering tents)
The room itself is used as a temperature buffer and gradient to remove hot air from the top and pump fresh cool air in at the bottom.
Two active fresh-air intakes at both ends of the room deliver fresh ambient air to the bottom of the space (anywhere from 50-80 degrees, 68-70 degrees most typical).
This cool air blanket forces warm air/tent exhaust up against the ceiling, where it is pulled through one of two carbon filters and then exhausted outdoors, removing the heat passively from the space.
The exhaust fan pulling through the carbon filters is oversized so that the room has a slight negative pressure to it, which helps with odor control, ensuring that all odorized particles pass through the carbon filters, since they are the areas of lowest pressure.
After pressure losses to ducting and the carbon filters, the scrubbers will exhaust the entire room at a rate of 12 air changes per hour. Is that enough?
Here's the diagram to assist in demonstrating the idea. This is a cross-sectional view (the top edge of the image is the ceiling and the bottom edge is the floor)
The room is basically broken down into three distinct environments:
1. The lighting stack (7x1KW HPS lamps in series, 8" air cooled hoods)
2. The flowering area (three 5x10 tents and one 5x5 tent)
3. The overall room (3500 cubic feet, taking into account the volume of the flowering tents)
I'll go through each area and outline what I have planned for passive temperature control, and I would love feedback on how well ya'll think this will work.
Area #1: The lighting stack. (7x1KW HPS lamps in series, 8" air cooled hoods)
This is a passively cooled string of lamps with a fresh ambient air intake and exhaust, so that the airflow is completely separate from the rest of the room.
An 800cfm fan will draw cool outside air through the reflectors, and then exhaust it back outdoors once it has passed over the lamps.
No carbon filter is needed since the intake is outside of the room, so the 800cfm fan will run pretty much full blast.
I estimate that after duct losses, there will be 500cfm flowing over the lights, which comes to about 5 seconds per air change through the stack (12 per minute / 720 per hour). Is that enough? Too much?
Area #2: The Flowering Tents. (three 5x10 tents and one 5x5 tent)
These tents have circulation fans inside, and a ducted exhaust fan pulling out of the top of the tents and venting into the larger room area.
The exhaust fans are currently sized to provide about 20 air changes per hour through each tent. Is that enough? Too much?
The exhaust fan will pull cool air in through the passive intakes in the bottom of each tent.
Area #3: The Overall Room. (3500 cubic feet, taking into account the volume of the flowering tents)
The room itself is used as a temperature buffer and gradient to remove hot air from the top and pump fresh cool air in at the bottom.
Two active fresh-air intakes at both ends of the room deliver fresh ambient air to the bottom of the space (anywhere from 50-80 degrees, 68-70 degrees most typical).
This cool air blanket forces warm air/tent exhaust up against the ceiling, where it is pulled through one of two carbon filters and then exhausted outdoors, removing the heat passively from the space.
The exhaust fan pulling through the carbon filters is oversized so that the room has a slight negative pressure to it, which helps with odor control, ensuring that all odorized particles pass through the carbon filters, since they are the areas of lowest pressure.
After pressure losses to ducting and the carbon filters, the scrubbers will exhaust the entire room at a rate of 12 air changes per hour. Is that enough?
Here's the diagram to assist in demonstrating the idea. This is a cross-sectional view (the top edge of the image is the ceiling and the bottom edge is the floor)
