How do I design a fan powered cooling system for my growbox?
There are a couple of factors you need to consider before choosing the type of fan and its orientation inside your grow box.
1. Calculate the volume of your growbox. To calculate multiply length x width x height of growing area e.g. A grow box that is 6’x3’x2′ will have a volume of 36 cubic feet.
2. Calculate the CFM Required. The fan should be able to adequately exchange the air in a grow room once every three minutes. Therefore, 36 cubic feet/3 minutes = 12 cfm. This will be the absolute minimum cfm for exchanging the air in a grow room.
3. Other factors to consider:
Unfortunately, the minimum cfm needed to ventilate a grow box is never quite that simple. Once the grower has calculated the minimum cfm required for their grow box the following additional factors need to be considered:
- Number of HID lights – add 5% per air cooled light or 10-15% per non-air cooled light.
- CO2 – add 5% for rooms with CO2 enrichment
- Filters – if a carbon filter is to be used with the exhaust system then add 20%
- Ambient temperature – add 25% for hot and dry ambient air and for hot and humid climates (such as Florida) add up to 40%
4. Plan your intake port. Your intake port should be ideally placed diagonally in the opposite corner of your exhaust fan. Decide whether you will be using active or passive air intake. You will greatly reduce the amount of work your exhaust fan will endure if you use an intake fan thus creating active air introduction instead of relying on passive air intake.
5. Plan the orientation of your fan relative to your carbon filter. You will always get better results if you pull or suck air through a carbon filter rather than pushing air. Place your fan/carbon filter combination at the highest point possible in your grow box. Doing so will exhaust the greatest amount of the waste hot air in your grow box.
Excellent air flow is essetial in a grow box environment is essential because of the close proximity of plants. Poor air flow in a grow due to choosing the wrong fan will invite unwanted pests and molds and growers into their grow boxes. And no grow box owner wants that!
Happy Growing!!
erik@supercloset.com
www.supercloset.com
Added by: snoofer Last edited by: snoofer Viewed: 449 times Rated by 16 users: 8.94/10 Contributed by: ranger2000 Submitted: 25-07-2003 Introduction: Every serious growing box needs cooling. Most of us use air cooling because it is cheap and very effective. The following steps are used to design a simple fan-cooled box. This method does not cover active cooling with air conditioning systems or ‘CoolTube’ designs. It is for grow chambers where the walls are approximately equal to the light pattern, totally enclosed for airflow control, and do not have large radiant heat into or out of the box. Your mileage may vary some for these reasons. I also picked sane defaults for growing conditions. The formulas diverge if you get too far out of plant growing range. You should be very safe if you are within about 40 to 150 degrees F and 20% to 90% humidity ranges (those are just guesses). Atmospheric pressure was picked as sea level and doesn’t really affect anything until about 5,000 or 8,000 fe
