Choosing the Right Fan for Exhaust System
Even when you're not worried about heat, it's still important to regularly replace all the air in the grow area, which means you need a way to vent out old air. An exhaust system uses fans and often ducting to move hot and humid air out of the grow space.
With any exhaust system, your goal is to vent out hot air, and replace it with fresh, cool air
Designing an efficient exhaust system will be much simpler if you take the time to understand airflow in a room - the whole idea of setting up an exhaust system is to create negative airflow in the grow space or grow tent so that any hot air is regularly replaced with new, fresh cool air.
All the air in the tent should be replaced by new air every 1-3 minutes for the best results. I recommend aiming to replace the air every one minute unless you live in a cool place. You can calculate the strength of exhaust fan you need based on the dimensions of your grow space.
In order to move air out of the tent and vent it outside, you need to use at least one strong fan as part of your exhaust system.
With every exhaust system, the idea is to vent out hot, humid or stale air, so it completely leaves the grow space
How to Calculate Exhaust Fan Strength
In the US, most exhaust fans have a "CFM" rating. This means "cubic feet per minute" and is talking about how much air the fan can move each minute. It's important to get a fan with the correct CFM rating for your size space.
In addition to CFM, there are 3 sizes that exhaust fans come in as far as diameter (how wide the fan is). They usually come in 4”, 6” or 8”. Generally it’s recommended to get a 6” for most setups, since most air-cooled hoods and ducting have a 6” opening. You can also use converters if you need to convert a 6” hold to a 4” fan. 8” fans are usually used for more high-powered grows.
You probably want a fan with a 6” diameter exhaust fan
Here's a short equation to help you determine what CFM rating you need for your fan in your space.
How to calculate CFM needed
Determine the cubic area of your space by multiplying Length x Width x Height. You want to exhaust this amount of air every minute.
Exhaust Efficiency - Every exhaust system has some level of inefficiency which will lower the amount of air being moved by the fan. This step tells you how much extra air-moving power needed to compensate. With an efficient exhaust, air goes in a short, straight line after passing through the fan. An inefficient path is when air has to go a long way after leaving the fan, or if the air has to go around turns instead of being in a straight line. This step will help make sure your fan is moving enough air to properly ventilate your space.
• Efficient path - multiply previous number by 2
• Inefficient path - multiply previous number by 3
Pick your fan. Fans are measured by CFM (cubic feet/minute), so you need a fan that has a CFM higher than the number you figured out in the last step.
Fan CFM Rating Table
(here are some examples of possible setups using the equation above to figure out CFM)
GROW SPACE SIZE WATTAGE OF LIGHT CFM OF FAN*
2’ x 4’ x 5’ 250W 80-120 CFM
3’ x 3’ x 6’ 400W 108 - 162 CFM
3.5’ x 3.5’ x 6.5’ 600W 160 - 238 CFM
4' x 4' x 7' 1,000W 224 - 336 CFM
* Of course fans don’t come in all these sizes, so round up to the closest fan size available.
You’ll generally need a higher CFM rating if your grow space tends to get hot or humid, and it's usually better to get an exhaust fan that is too big than one that is too little!
... ..cheerz...h00k...
...as stated...your fan should do you just fine...maybe a little on the small side...you might consider starting a journal when You're underway...always people around to offer advice/support...cheerz...h00k...