Is an intake fan necessary?

ThatGuy1985

ThatGuy1985

Well-Known Member
yes and no if you have an intake fan you need to have an exhaust that is double the intake in cfms or buy 3 fans use 2 for exhaust and one for intake. You dont need an intake fan though just make sure your intake hole is smaller than your exit
 
BigBudBalls

BigBudBalls

Well-Known Member
An intake fan can actually hurt you.

A fan is rated at CFM. But that rating isn't a given.
If there is no way for new air to get in, that number drops.
If there are turns, that number drops
If there is a smaller duct, that number drops
The length of the duct drops the number.

An intake fan can create eddys that can inhibit the exhaust fan.

A quick test is to have both. Keep 'em off and let the lights heat the room up and test the time needed to drop it say 5^. Then remove (not turn off) the intake and repeat.
 
nickfury510

nickfury510

Well-Known Member
tusseltussel said:
how to confuse a newbie:confused:
Click to expand...

this is from the growfaq

How do I add ventilation to my grow area?


How do I add ventilation to my grow area?



Contributed by: Smokey D Dope

How do I add ventilation to my grow area?
There are a couple of considerations to observe when planning your ventilation, they’re pretty simple concepts; but they are often overlooked.

· First, remember that warmer air will naturally rise to the top of any container, and that cooler air will naturally settle towards the bottom.
· Also remember that when ventilating any space, the volume (VOLUME, in cubic feet or cubic meters... [L x W x H]) of air that goes IN, also has to come OUT.
· You can’t expect to ventilate a grow space by simply forcing air in, and not providing an exhaust vent.

Since the object is to remove as much warm air as possible, and replace it with cooler air, it will be most efficient to place the exhaust as close to the top of the space as possible, and place the intake as close to the bottom as possible.


Should I place the fan in the exhaust, intake or both?
The fan should be placed in the exhaust, and the intake should be a simple hole (or light trap, if light getting out is a concern).
This type of system is known as an Active Exhaust, Passive Intake System.
Mounting the fan in the exhaust, sucking air out of the room accomplishes a couple of things...

· Since the exhaust is at the top of the area, the fan will suck the hottest air out of the area first.
· The fan is actually lowering the air pressure inside the area. Any incidental pinholes or leaky seams will simply draw air in. If the fan were blowing IN, those pinholes and leaks would allow potentially smelly air OUT.


How big should the passive intake be?
It should be slightly larger than the exhaust. Remember, the volume of air being blown out, will be replaced through the intake. Using a bigger intake hole allows the incoming air to be at a lower velocity (speed), which minimizes mixing up of the air in the area. It will also allow the fan to operate more efficiently.


How big should the fan be?
Fans are rated in either cubic feet (CFM) or cubic meters per minute in North America. In Eurpose, metric fans are rated in m3/hr - cubic metres per hour (m3/hr).

That means a 70CFM fan will move 70 cubic feet of air in one minute.
Your fan should be big enough to move the volume of your area 2 to 3 times every minute. A 70 CFM fan would be adequate for a 35 cubic foot area, and would be optimal for roughly a 23 cubic foot area.

· To figure your area’s cubic volume, multiply (in feet) the length by the width by the height.


What if I have more than one fan? Should I use one to blow air in and one to suck air out?
Not if the object is to provide as much ventilation and cooling as possible.

· If you have two 3-inch diameter fans, and you mount one in the intake, and one in the exhaust, you have a total intake area of one 3-inch hole and a total exhaust area of one 3-inch hole.
· If you use both fans as exhausts, you have TWO 3-inch exhausts and two 3-inch intakes (actually, two 3.3 inch intakes. They should be bigger than the exhausts, remember?).
· Twice as many holes, twice as much airflow.


Enhanced Blower Mods

Timer Options
If you find that the "Lights off" temps are lower than you'd prefer, you can simply run the fan from the same timer as the light by using a multi outlet power strip connected to the timer. Plug the lights and the fan into the power strip, and the fan will turn on/off with the lights. If you're using more than one fan, you could connect some or all of them, remembering that the more fans you have running, the lower the temps will be.
* SAFETY NOTE: The timer must be able to handle the additional electrical load, or an additional timer must be used. SAFTEY FIRST.

Sound Suppression
Making the ventilation system quieter can be an important consideration, and it's important to remember that the air moving through the intakes and exhausts make noise, as well as the fan itself. Some of the fan noise from vibration can be overcome by mounting the fan in a non-rigid manner. The fans can me mounted using rubber grommets to help dampen the vibration. Self-adhesive foam rubber window insulation can also be used. In some installations, it can be mounted by threading a bungee cord through each mounting hole, then attaching the other ends of the bungee cord to the exhaust hole.

· Generally, air moving through ductwork or tubing can become noisy, particularly if the air has to move at a higher velocity. More, larger diameter intakes and vent tubes will generally be quieter than fewer, smaller diameter intakes and vents. The fans also don't have to work quite as hard.
· Finally, although popular and easy to use, flexible "Accordion" type hose, commonly used to connect clothes dryers to external vents are not always the best choice, as they cause a great deal of drag, (making the fans work harder) and generally air flowing through them is noisier than smoother ductwork.

FilteringOdor Control
Connecting a Carbon scrubber is a good method of controlling the odor that can be a dead giveaway to an otherwise stealthy installation. A carbon scrubber is simply an expansion chamber (box) into which the smelly air from a flower chamber is pumped. The chamber has a large exhaust vent, which is covered by an activated carbon air filter. The chamber must be big enough to provide a damping effect of the incoming air. If too small a scrubber is used, the fan will not be capable of pushing air through the filter. Here, you actually want the exhaust vent to be considerably bigger than the intake.

· There are also several DIY Odor killers available, which work to varying degrees to provide an "Odor Cover-up."
· Remember, the term "Low Odor Strain" is relative.
· Even the low odor strains generally still stink pretty badly near the end of flowering.

Now go grow something!:hump::joint:
 
tusseltussel

tusseltussel

Well-Known Member
thanks but my room has been working fine for a few years. i bet the guy who posted this thread could have found that just as easy as you did, i just wanted to point and laugh at the fact that this guy had 3 posts 2 of which were exactly opposite. so i commend you on a job well done straightening out the confusion between posters
 
tommo9090

tommo9090

Well-Known Member
tusseltussel said:
thanks but my room has been working fine for a few years. i bet the guy who posted this thread could have found that just as easy as you did, i just wanted to point and laugh at the fact that this guy had 3 posts 2 of which were exactly opposite. so i commend you on a job well done straightening out the confusion between posters
Click to expand...
are you some kind of fucking retard?
 
tusseltussel

tusseltussel

Well-Known Member
tommo9090 said:
are you some kind of fucking retard?
Click to expand...
dude why am i a retard, didn't i just help you by pointing out the fact that you had 2 posts one saying larger hole one saying smaller and didn't that push someone into posting the right info for you which you could have found yourself. im not gonna call you names because that would be retarded
 
tommo9090

tommo9090

Well-Known Member
tusseltussel said:
dude why am i a retard, didn't i just help you by pointing out the fact that you had 2 posts one saying larger hole one saying smaller and didn't that push someone into posting the right info for you which you could have found yourself. im not gonna call you names because that would be retarded
Click to expand...
your post was intentionally ambiguous.
i and im not name calling it was a serious question :)
 
tusseltussel

tusseltussel

Well-Known Member
the way i see it i helped your dumb ass so now im name calling....... i hope your plants die anus. i will never post on one of your threads again i don't need some fuckin kid gettin upitty cause i helped bye hope you figured out what to do for your exhaust
 
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