How to ventilate a grow room?
Air exchange in a grow room helps keep the temperature down and regulates Co2 levels. A high-powered fan blowing outside will cause an opposing vent across the room to suck in air.
But how do you know the power of a fan to get and just how do you know when the room has had a complete air exchange?
Fortunately, there is a formula to determine this. First, we need to find the CFM or ‘cubic feet per minute of the grow room.
Determine this by multiplying the length of the room times the width times the height.
This calculates the CFM to exchange the air in the grow room within 5 minutes since air should be exchanged at least every 5 minutes and more preferably every minute.
Take the 5-minute CFM and divide by 5 for the 1-minute CFM. Example: Room is 10 by 10 and 7 feet in height which is a CFM of 10x10x7=700
So fan rates at 700 CFM will exchange the air in the room every 5 minutes. Divide 700 by 5 = 140 CFM to circulate the air every minute.
Ventilation is important for a grow room because it removes the hot, stale air and replaces it with cool, fresh air. It can be done in two ways: an exhaust system that draws old, warm air out at the top of your grow space or you can use simple fans to move air around. Regardless of which method you choose, make sure you have proper ventilation when growing cannabis plants indoors!
If you’re using an exhaust system, chances are good that either a fan or some type of ducting will be needed as well. The best way to keep your grow space ventilated is by using an exhaust system that draws old (warm) air out on top while drawing cool (fresh) air up through the canopy of your plants.
The right exhaust system will depend on the size of the space: for smaller spaces, you can use a simple fan; for larger spaces, an intake and two-stage exhaust may be needed to move enough air. Regardless of which type is used, make sure that fresh air is being replaced with old (warm) air in order to maintain adequate levels of oxygen, CO² and humidity within your grow space!
If using fans to ventilate your grow room instead of an exhaust system or ducting then take care not to point any one direction as this could create a draft effect – aim them all over the general area so that stagnant areas get mixed up with new ones. Large rooms should have at least three oscillating fans or two oscillating and one non-oscillating.
You might also consider installing humidifiers in some areas to maintain a near constant humidity level. If you have an exhaust system that is drawing old (warm) air out on top, then make sure the intake is near the bottom of your grow space.
The system should be working for at least 15 minutes before going to sleep in order for it to have enough time to dehumidify and cool the room, or else you may wake up to condensation on walls!
On hotter days (between 20-28 degrees Celsius) try turning off ventilation as this will make a considerable difference in temperature inside your grow space.
Growers often also use mesh screens on vents during flowering because they help keep down pests such as thrips that can cause mold issues when breathing through vent holes. If using an exhaust system with filters then clean them regularly – every two weeks is ideal but if smelly air cannot be helped then do so more frequently than that.
The best GROW TENT VENTILATION
The best GROW TENT VENTILATION is achieved by using an exhaust system that draws old, warm air out at the top of your grow space and drawing cool, fresh air up through the canopy of your plants.
If you are using other methods to move or circulate air in your grow room then make sure there’s enough ventilation! Even if these systems do not directly touch any part of a plant they can still create drafts which will hurt growth rates – so be careful when choosing what kind of fan(s) you want to use! If possible, it’s also worth looking into installing humidifiers in areas where humidity levels are low and screens over vents during flowering time.
In order for the ventilation system to work properly, it should be running for at least 15 minutes before going to sleep in order for the system to have enough time and cool down your grow space.
NLINE DUCT FAN (ACTIVE EXHAUST FAN)
An extractor fan is a way to make air inside your room or tent cooler. When the air is hot and humid, it can affect how well plants grow. If you use an extractor fan, you can keep a pleasant climate inside the room for your plants to grow in.
If you grow in an enclosed space it will be hotter than outside. To keep the temperature inside to a moderate level, use the active exhaust fan to bring cooler air. The location of your grow space will affect how hard the inline duct fan has to work. This is dependent on how well insulated your grow space is.
In a passive intake system, inline duct fans can also act as vacuum cleaners. They bring in air which has fresh CO2.
Ducting attaches to your inline vent fan and routes air from the grow room. It is made of metal, but if it does get ripped it can be fixed in a few different ways. The size and length of the ducting will affect how well your inline vent fan performs.
Carbon filters are a tool that can help keep smells from spreading. They also trap pollen and spores to keep the air clean for people with allergies or asthma.
Typical Grow Tent Setups
There are many ways to configure these components. One way is to have the fan and filter inside, which makes it easier and quieter. You can also put them in any order if you want to pull air out of your grow space.
Ventilation systems can be set up in a lot of ways. The direction of the cool air might be different than the direction of the lights.
We recommend setting the fan at the top of your house so it will take out the hot air. The carbon filter will also work better if you put it at the top of your house.
What Size Inline Fan do I Need?
There are different size grow spaces. To get fresh air in, you need a certain amount of airflow. You need to figure out the CFM (cubic feet per minute).
To find the airflow needed for your grow space, first figure out how much space you have. Then multiply this by its length, width and height. This will show you how many cubic feet of air moves each minute, or CFM. Here is what the formula looks like:
For example, a 48”x36”x72” grow tent converted to feet would be a 4’x3’x6’ grow tent. Multiplying the dimensions together would equal 72 ft3. Since a grow space’s volume is also the required CFM to ventilate it every minute, this grow tent’s base CFM is 72. Hold on to this number, as you will need to account for the ducting, carbon filter, and other accessories you might add.
FACTORING IN ACCESSORIES
The next step is to increase your CFM by the efficiency of your accessories. If you put in ducting and carbon filters, they will reduce the amount of air that a fan can move which affects how big the fan needs to be.
When it comes to ducting, the number and sharpness of its bends factor into the airflow resistance. This is because airflow reduces the further it must travel so the straighter the ducting route, the better. The sharper the bend, the harsher the efficiency reduction; a 30° bend cuts the amount of airflow by 20% while a 90° bend diminishes airflow by 60%. Smoothing out any wrinkles can also improve fan performance and airflow.
If you are using LED grow lights, you must also account for its heat output which further increases your required CFM by up to 50%.
If you want to be able to move the air, then your fan needs to be high-performing. You might have accessories that can help you. These can be very different depending on what type of component they are. You should look at a table for an approximate efficiency percentage.
(Base CFM x Component factors) x (Grow light heat) = Required CFM
For example, our 4’x3’x6’ grow tent has a baseline CFM of 72. We multiply this figure by the efficiency percentage of each component. If we add a carbon filter (60%), ducting (~20%), and a silencer (20%) to our ventilation system, we get 166 CFM. From here, factoring in your grow light’s heat output (≤50%) will give us a required CFM of 249. Keep in mind that these percentages are not fixed and may vary. Here is the breakdown of this calculation:
Multiplying your base CFM (72) by the ducting (20%), carbon filter (60%), silencer (20%), and grow light heat (50%) of your choice will yield about a required 249 CFM.
When shopping for a fan system, we recommend one with fan speed controls and a 25% or greater CFM rating than your minimum requirement, especially if using a filter. This will allow the fan to run quieter at lower speeds and give you room for future grow space system expansion. Look for inline duct fans that use DC fan motors that operate the quietest compared to AC fan motors. PWM-controlled EC motors are acoustically acceptable as well.
How to Manage Grow Space Noise?
When you use a high-powered fan to ventilate your grow space, it will make some noise. You don’t want to hang out in an area with too much noise pollution for long or one that draws attention from your neighbors. But you can make the component selection with silencing in mind and take additional measures to make your room quiet.
Choosing a fan with speed controls and a 25% higher CFM rating than your minimum requirement will allow you to run the fan at lower speeds without sacrificing performance. Whether you are growing a tent or a room, you can apply soundproofing all around your grow space to diminish the fan humming. To add further silencing to your active exhaust fan, you can attach a silencer that will dampen the intake sound. You may also opt for insulated ducting instead of using standard ducting to reduce the whooshing wind noise.
Where do you vent a hot air from a grow room?
Depending on the size of your space, you can also use simple fans to move air around.
This ensures that hot air isn’t accumulating below-ground where it could easily build up heat until it becomes a safety hazard. (Base CFM x Component factors) x (Grow light heat) = Required CFM If you are using LED grow lights with high heat output (>50%), then most people recommend adding 50% more CFMs
How often should air be exchanged in GROW ROOM? Depending on the size of your space, you can also use simple fans to move around and ventilate your room. The best way to keep your GROW ROOM ventilated is by using an exhaust system that draws old, warm air out at the top of the GROWROOM/Tent and draws cool fresh air from the bottom of your GROWROOM/Tent up through the plant canopy. This ensures that hot air isn’t accumulating below-ground where it could easily build up heat until it becomes a safety hazard. (Base CFM x Component factors) x (Grow light HEAT) = Required CFM If you are using LED GROW LIGHTS with high HEAT output (>50%), then most people recommend adding 50% more GROWS to make sure there is enough ventilation in your grow space so plants can thrive and not be harmed by too much heat or humidity.