# Inline fans, push or pull air?



## bam bam (Jun 2, 2009)

I have read that inline fans are propulsive, so they are best used to push air instead of pulling air?

What should my set up be.

1)window(source of fresh air)-->inline fan(pushing air)--> 5FT of duct-->cooltube-->exhaust out

OR
2)window(source of fresh air)--> 5FT of duct--> cooltube -->inlinefan(pulling air)--> exhaust out


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## nathenking (Jun 2, 2009)

I honestly dont think it makes that much of a difference brother... just my 2cents


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## jimbizzzale67123 (Jun 2, 2009)

In all seriousness even if it does make a samll difrence there really wont be much of a dramatic change.


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## abellguy (Jun 2, 2009)

I would say the only thing that would make a difference would be if you were changing duct sizes at all, you would want to go from big to small not the other way around that would give you best air flow. Hope this helps


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## LUDACRIS (Jun 2, 2009)

bam bam said:


> I have read that inline fans are propulsive, so they are best used to push air instead of pulling air?
> 
> What should my set up be.
> 
> ...


 
_a window or oscillating fan for fresh air input and a extractor fan(ruck fan)for exhaust._
_always mount your exhaust fan ducting at the top of the grow room as the hoter air is always at the top of your room/growroom._
_you can also mount a 6" desk fan(as i do) pointing at your lamp/bulb to keep it cool._
_i use 3 oscillating fans._
_1(16") to blow around the room._
_2(6") to blow directly on to my lamp._
_3(8") blowing gently on my plants._
_as well as my 5" ruck/extractor fan to suck it all up dispersing it into another room._
_always mount your exhaust ducting level with the roof._
*LUDACRIS.*


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## weedicus (Jun 3, 2009)

i've heard they pull better than push, but i have no evidence to back that up. its just the way i've always hooked it up


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## dbo24242 (Jun 3, 2009)

exhaust the cooltube air out the window, otherwise you aren't doing anything but moving the heat inside of the room. you want to pull the heat out of the room.


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## Mcgician (Jun 3, 2009)

Better to exhaust than to push in. One, the passive intake will work much better than a passive exhaust, and the cfms from the exhaust will be closer to their actual capabilities than an intake mounted system (provided there's not too much ducting between the fan and wherever the exhaust air is going). 

The only situation I know of where pushing air is better is when you're using can fan's to push cold air into hot, air cooled reflectors.


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## SpruceZeus (Jun 3, 2009)

Its my understanding that pulling is better.


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## abellguy (Jun 3, 2009)

SpruceZeus said:


> Its my understanding that pulling is better.


 
I would be interested in understanding why?! I am sure it is easy enough for people to change polls on the motor of fans if one way is better!!

It seems if heat is inside the hood and your goal is to get that heat out of the room. If you have a duct that starts outside the room pref in a cool area and then run to your fan and through your lights and then out you will have the majority of the "strong" flow at the cool side pushing the heat out (so maybe putting a little more cool air to the lights)
and the other way around the "strong" flow would be better at pulling the heat out with the flow of cool air directly to the hood being somewhat reduced seeing how the fan is farther away.

I would like to know for future use, I know with the ice box its best to have a fan blowing through the hood, through ice box "radiator" then into room, don't know if there is any relevance here?


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## DaBull (Jun 3, 2009)

There is NO difference between push or pull with respect to the cool tube. But for the plant compartment, Ludacris is right about pulling hot air out from the top.


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## LUDACRIS (Jun 3, 2009)

*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. 

*Filtering\Odor 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. 

*LUDACRIS*.


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## BigBudBalls (Jun 3, 2009)

just my 2cents, but I rather push. Reason being it gives more molecules at the light to absorb heat. Now some may say the push will compress the air raising its temp, but the light is going to raise it anyways.

(also my fan has plastic blades/impeller, so rather not have the hot air on that)

But all in all, I don't think it really matters


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## LUDACRIS (Jun 3, 2009)

_its really all down to each and everybodys individual growing environment/growroom/grow area/space etc etc._
_its about finding whats best for your individual needs and growing environment and finding simply what works best and appliying the nessesary requirements for perfect growing conditions for your garden._
_whatever way you go about it you must recirculate the growroom air by exhausting(sucking) air out from the room(roof) and replenishing the expelled air by either an intake fan or a simple window or opening your growroom door regularly replenishing the exhausted air.cool tubes are really a waste of time and are not reqd.all you need is a small 6" fan blowing on your lamp and thats probably better in my opinion for cooling your lamp.the fan blowing on to your lamp(if quite strong) will allow your lamp to swing on its hangings which is not exactly a light mover but its good for no extra expense._
_there is absouloutely no need to cooltube a lamp with ducting and fans when 1 fan is a much better simpler cheaper and better option._

*LUDACRIS.*


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## MyGTO2007 (Jun 3, 2009)

thats badass Lud, you know alot about Air movement....cool me too..been doing alot of research on it ...its a science just like you said, their has to be a balance to it!! check out my Room just got done with it 3 wks ago.... Im using a S&P 6'' exhaust 293 cfm and the same for the intake ported at bottom, now i will have a 4'' S&P for my lights,(they both have a 100cfm in them)

But Pull up a chair load a bowl and check out my journal !! +rep for the post


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## MyGTO2007 (Jun 3, 2009)

LUDACRIS said:


> _its really all down to each and everybodys individual growing environment/growroom/grow area/space etc etc._
> _its about finding whats best for your individual needs and growing environment and finding simply what works best and appliying the nessesary requirements for perfect growing conditions for your garden._
> _whatever way you go about it you must recirculate the growroom air by exhausting(sucking) air out from the room(roof) and replenishing the expelled air by either an intake fan or a simple window or opening your growroom door regularly replenishing the exhausted air.cool tubes are really a waste of time and are not reqd.all you need is a small 6" fan blowing on your lamp and thats probably better in my opinion for cooling your lamp.the fan blowing on to your lamp(if quite strong) will allow your lamp to swing on its hangings which is not exactly a light mover but its good for no extra expense._
> _there is absouloutely no need to cooltube a lamp with ducting and fans when 1 fan is a much better simpler cheaper and better option._
> ...


 
And yes your right on that,
every room is different


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## LUDACRIS (Jun 3, 2009)

MyGTO2007 said:


> thats badass Lud, you know alot about Air movement....cool me too..been doing alot of research on it ...its a science just like you said, their has to be a balance to it!! check out my Room just got done with it 3 wks ago.... Im using a S&P 6'' exhaust 293 cfm and the same for the intake ported at bottom, now i will have a 4'' S&P for my lights,(they both have a 100cfm in them)
> 
> But Pull up a chair load a bowl and check out my journal !! +rep for the post





MyGTO2007 said:


> And yes your right on that,
> every room is different


_thanks mate i am already on the bowl._
__

*LUDA.*





(just ask).


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## bam bam (Jun 3, 2009)

BigBudBalls said:


> just my 2cents, but I rather push. Reason being it gives more molecules at the light to absorb heat. Now some may say the push will compress the air raising its temp, but the light is going to raise it anyways.
> 
> (also my fan has plastic blades/impeller, so rather not have the hot air on that)
> 
> But all in all, I don't think it really matters


I think pushing is also better. You probally dont want all that hot air running through your fan.

If you put your fan after your intake but before your long ducting both your intake and exhaust are not compromised and will be able to operate at its highest CFM. Sure since you are pushing air through the long ducting it might take a longer time for your cold air to get to the bulb, but eventually it does and it will push the hot air out. Your CFM is only reduced at the bulb and not at the fan.

If you connect your fan after the long ducting then you compromised your intake so now you fan's exhaust will have less air to push into your bulb. So now your cfm is reduced at the fan's intake, the fan's exhaust and also at the bulb.


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## LUDACRIS (Jun 3, 2009)

bam bam said:


> I think pushing is also better. You probally dont want all that hot air running through your fan.
> 
> If you put your fan after your intake but before your long ducting both your intake and exhaust are not compromised and will be able to operate at its highest CFM. Sure since you are pushing air through the long ducting it might take a longer time for your cold air to get to the bulb, but eventually it does and it will push the hot air out. Your CFM is only reduced at the bulb and not at the fan.
> 
> If you connect your fan after the long ducting then you compromised your intake so now you fan's exhaust will have less air to push into your bulb. So now your cfm is reduced at the fan's intake, the fan's exhaust and also at the bulb.


 
_absoloute nonsense mate._
_look at any grow boxes/tents that you can buy from hydro stores and you will see whats what._
_EXHAUST AT THE ROOF AND INTAKE FROM ELSEWHERE!!!!!!!!._
_*LUDACRIS.*_


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## LUDACRIS (Jun 3, 2009)

_*How do I install a duct fan to operate most efficiently? 
*(principles of effective ventilation) 

Many growers own fans powerful enough to move air of a city block in Manhattan, but has failed to install it properly, causing greater pressure reduction. This extra pressure drop is called the system effect or system dissipation, and can cause the fan to produce a smaller volume of air than indicated in the fan diagram. 

The following factors must be considered in order to avoid system dissipation: 

*At the Inlet* 

_
_The distance to the nearest wall must be more than 0.75 the inlet's diameter. 
__The inlet duct's cross section must not be greater than 112% or less than 92% of the fan inlet. _
_The inlet duct's length must be at least 1 x the duct diameter. 
__The inlet duct must no have any obstacles to the air flow (dampers, branching or similar). 


*At the outlet* 

__The angle at the reduction of the duct cross-section must be less than 15 degrees 
__The angle at the enlargement of the duct cross-section must be less than 7 degrees 
__A straight length of at least 3x duct diameter is required after a duct fan. 
__Avoid 90 degree bends (use 45 degree) 
__Bends must be shaped so that they follow the air stream after the fan. 

If the connections are different from this, there could be a greater pressure reduction.




__Circular duct fans for example, are propulsive, pushing the air. And should be installed so that the long duct is after the fan itself._

_*LUDACRIS.*_


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## dube (Jun 3, 2009)

i had a fan pulling hot air out from a duct to the cool tube and drawing [from a duct] fresh air in but the fan did not last 12 months it over heated .now the new one blows cold air in and its still working fine


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## abellguy (Jun 3, 2009)

BigBudBalls said:


> just my 2cents, but I rather push. Reason being it gives more molecules at the light to absorb heat. Now some may say the push will compress the air raising its temp, but the light is going to raise it anyways.
> 
> (also my fan has plastic blades/impeller, so rather not have the hot air on that)
> 
> But all in all, I don't think it really matters


 
That is a good explanation on why I settle on pushing when I am faced with which to choose. Thanks


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## LUDACRIS (Jun 3, 2009)

dube said:


> i had a fan pulling hot air out from a duct to the cool tube and drawing [from a duct] fresh air in but the fan did not last 12 months it over heated .now the new one blows cold air in and its still working fine


 
_buy a descent extraction fan and mount it properely and its everlasing._
*LUDACRIS.*


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## morrisgreenberg (Jun 3, 2009)

ludacris, i am still confused, i kept reading your posts and its all correct, but he is cooling a cooltube, totally sealed off from the grow room enviroment, yes having your hot air exhaust at the top of room for heat and humidty control, but thats not the question here, bigbudballs said he didnt like the idea of having hot air passing over and thru his fan, he is correct about that, every proper setup i have seen whether independant from grow room enviroment or with carbon scrubber attatched always had Filter->>Fan->>Tube/Hood->>out the room, i run my carbon filter seperate from the colling system, and i run several lights inline, i always prefer fresh air>>hood>>exhaust out....in these setups we arent totally cooling cus you still will get some heat , we are just trying to shuffle the added buklb heat out of the room


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## morrisgreenberg (Jun 3, 2009)

ludacris, i am still confused, i kept reading your posts and its all correct, but he is cooling a cooltube, totally sealed off from the grow room enviroment, yes having your hot air exhaust at the top of room for heat and humidty control, but thats not the question here, bigbudballs said he didnt like the idea of having hot air passing over and thru his fan, he is correct about that, every proper setup i have seen whether independant from grow room enviroment or with carbon scrubber attatched always had Filter->>Fan->>Tube/Hood->>out the room, i run my carbon filter seperate from the colling system, and i run several lights inline, i always prefer fresh air>>hood>>exhaust out....in these setups we arent totally cooling cus you still will get some heat , we are just trying to shuffle the added buklb heat out of the room


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## morrisgreenberg (Jun 3, 2009)

i dont know why it double posted, anyhows, you guys are talking plastic blades, i think your using duct fans, these are good to cool a single 400 or 600watter, but having this type of fan at the end of the system will burn out, or at the very least need to be oiled up every few months, whichever way you feel comfortable putting your fan, invest in a proper fan and it wont let you down. Personally i use HTG's 6inch growbright fans and they been in service for a year now nonstop and keep on truckin


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## LUDACRIS (Jun 3, 2009)

morrisgreenberg said:


> i dont know why it double posted, anyhows, you guys are talking plastic blades, i think your using duct fans, these are good to cool a single 400 or 600watter, but having this type of fan at the end of the system will burn out, or at the very least need to be oiled up every few months, whichever way you feel comfortable putting your fan, invest in a proper fan and it wont let you down. Personally i use HTG's 6inch growbright fans and they been in service for a year now nonstop and keep on truckin


 
_not to sure what you mean but as for the best extraction fans keep rucking mate._
http://www.greenshorticulture.co.uk/Growroom-Products-20/-In-Line-Fans-Fan-Filter-Deals-108/RUCK-Fans-101.asp

*LUDACRIS.*


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## LUDACRIS (Jun 3, 2009)

morrisgreenberg said:


> ludacris, i am still confused, i kept reading your posts and its all correct, but he is cooling a cooltube, totally sealed off from the grow room enviroment, yes having your hot air exhaust at the top of room for heat and humidty control, but thats not the question here, bigbudballs said he didnt like the idea of having hot air passing over and thru his fan, he is correct about that, every proper setup i have seen whether independant from grow room enviroment or with carbon scrubber attatched always had Filter->>Fan->>Tube/Hood->>out the room, i run my carbon filter seperate from the colling system, and i run several lights inline, i always prefer fresh air>>hood>>exhaust out....in these setups we arent totally cooling cus you still will get some heat , we are just trying to shuffle the added buklb heat out of the room


_this makes no sense to me there is no need for cooltubeing lighting fixtures or carbon filters if you exhaust the growroom efficiently._
_*LUDA.*_


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## LUDACRIS (Jun 3, 2009)

morrisgreenberg said:


> ludacris, i am still confused, i kept reading your posts and its all correct, but he is cooling a cooltube, totally sealed off from the grow room enviroment, yes having your hot air exhaust at the top of room for heat and humidty control, but thats not the question here, bigbudballs said he didnt like the idea of having hot air passing over and thru his fan, he is correct about that, every proper setup i have seen whether independant from grow room enviroment or with carbon scrubber attatched always had Filter->>Fan->>Tube/Hood->>out the room, i run my carbon filter seperate from the colling system, and i run several lights inline, i always prefer fresh air>>hood>>exhaust out....in these setups we arent totally cooling cus you still will get some heat , we are just trying to shuffle the added buklb heat out of the room


_as you can see a basic growtent exhaust at the top and intake at the bottom i could find another 100 pics but i am too boned and dont feel like arguing._
http://www.greenshorticulture.co.uk/Grow-Tents-353/Dark-Room-Grow-Tent-Packages-485/Dark-Room-Street-DRS120-Grow-Tent-Package-1216.asp

*LUDACRIS.*


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## SpruceZeus (Jun 3, 2009)

LUDACRIS said:


> _this makes no sense to me there is no need for cooltubeing lighting fixtures or carbon filters if you exhaust the growroom efficiently._
> _*LUDA.*_


You speak in absoloutes.
There are a million ways to set up a growroom. What works for me doesn't always work for you.
Are you stating that air cooled reflectors are never a part of an efficient growroom? or carbon filters?
Please clairify, because it sounds like you're off your rocker.


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## LUDACRIS (Jun 3, 2009)

SpruceZeus said:


> You speak in absoloutes.
> There are a million ways to set up a growroom. What works for me doesn't always work for you.
> Are you stating that air cooled reflectors are never a part of an efficient growroom? or carbon filters?
> Please clairify, because it sounds like you're off your rocker.


*yes* i am stating that air cooled reflectors are exellent for an efficient growroom but not by the use of a cool tube set up and there is no benefit to plant growth by installing a carbon filter to your exhaust or a cooltube to your lamp.
filters are only in place to dissapate smells/oudours and cool tubes are in place to cool the lamp.
now tell me how installing a carbon filter or cool tube is going to better my yeild.... and how will a cooltube make my lamp any cooler than it is with a fan blowing on it .
and yes i am totally off my rocker as you say and i dont see that as relevant unless you have a different view.
*LUDA.*


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## bam bam (Jun 3, 2009)

LUDACRIS said:


> now tell me how installing a carbon filter or cool tube is going to better my yeild.... and how will a cooltube make my lamp any cooler than it is with a fan blowing on it .
> *LUDA.*


Well with a cooltube working properly, you can have your canopy closer to the bulb and not get plant burn.

The heat that is given off by the bulb generally stays inside the cooltube, and then gets pushed or pulled out of the grow closet. The heat will have less impact on the ambient temperature of the grow closet.

Having a fan blowing on your lights just spreads heat around your closet, but the heat will be taken out of your closet by the exhaust fan.


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## BigBudBalls (Jun 3, 2009)

Well my hood (not cool tube but basically the same.) gets it's air from outside the room and exhausted outside the room. The light air and room air never mix. So the light cooling is separate from everything else.
I have no filters/scrubber. I do have circulation fans exclusive of the light/hood cooling.

My point was the # of air molecules to absorb therms/BTUs as it passed by the bulb. At a negative pressure, its less, if positive pressure its more.



morrisgreenberg said:


> ludacris, i am still confused, i kept reading your posts and its all correct, but he is cooling a cooltube, totally sealed off from the grow room enviroment, yes having your hot air exhaust at the top of room for heat and humidty control, but thats not the question here, bigbudballs said he didnt like the idea of having hot air passing over and thru his fan, he is correct about that, every proper setup i have seen whether independant from grow room enviroment or with carbon scrubber attatched always had Filter->>Fan->>Tube/Hood->>out the room, i run my carbon filter seperate from the colling system, and i run several lights inline, i always prefer fresh air>>hood>>exhaust out....in these setups we arent totally cooling cus you still will get some heat , we are just trying to shuffle the added buklb heat out of the room


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## dbo24242 (Jun 4, 2009)

gotta say, I use a 1,000w in a closet of appx 7sq ft, exhausting a cooltube into the attic behind the closet w/ an air conditioner in the room. 1,000w would normally cook everything, especially with 80 deg days, but I exhaust the heat created by the lamp and the natural flow into the closet is from the reservoir of cool air I reside in. works pro.

now if I use the 400w light in the tube I want to blow in to the room and mix that warm air with the a/ced air to get a nice comfy temp. this also keeps the temp in the rest of the house down because the attic is allowed to properly cool. Either way I'm pulling air from the cooltube and directing heat elsewhere, the point is to remove the excess heat, and in 1,000w applications this is pretty key.



Oh and if it wasn't answered, the reason pulling is more efficient all has to do with Bernoulli. There is a low pressure zone in the fan area no matter what. If you are pulling, the low pressure zone is directed out into an open area and air is not constricted. when pushing into the duct, however, the low pressure zone is followed by the higher-pressue air travelling at lower velocity until the end of the tunnel. Ideally you push and pull and remove as much pressure from inside as possible, but with only one fan it will accomplish more pulling air from the duct.


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## dbo24242 (Jun 4, 2009)

LUDACRIS said:


> now tell me how installing a carbon filter or cool tube is going to better my yeild.... and how will a cooltube make my lamp any cooler than it is with a fan blowing on it .


cooltube is made so you take the heat created by the lamp and direct it elsewhere, out a window, in a different room, in an attic, to a basement, to a sewer system. it just removes the heat very efficiently. also, it is reasonably small and good for vertical applications.
it improves yield because you can place a 1,000w as close a 1 ft away and closer with a more powerful fan. minor loss of light to the glass interface, but same deal with an air cooled glass lens reflector. open air cooled reflectors take air from the entire chamber and will interrupt CO_2 if it is added, so you don't want to use open reflectors for air cooling anyways, thats why I invested in a cooltube, its all about isolating each component's problems.


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## IAm5toned (Oct 4, 2009)

depends on the application... pushing works better for feeding air into a space.. pulling works best for venting air out of a space. the ideal setup would be one fan pushing cool air in down low, and another fan pulling hot air out up top


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## Jaiixd (Oct 4, 2009)

i always have one pulling air in and one pushing air out


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## quosulfir (Oct 4, 2009)

Can you give some more sample question and answers. How great your info is! It really useful for me. Thanks.


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## quosulfir (Oct 4, 2009)

Can you give some more sample question and answers. How great your info is! It really useful for me. Thanks.
_________________
Cheap tennis ball machine for sale | Used lobster tennis ball machine | Review of Tennis twist, Playmate, Little Prince and Wilson tennis ball machines


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## fluffygrrrl (Oct 4, 2009)

I have been researching this issue for months, and I'm still confused, because everybody does it different. Ludacris, how would you set up the exhaust if you are in a basement? My intake has to come from either a window or a spot under an addition, which would be ceiling height. Do I take the vent and drop it down to the floor? Or just take the intake in a straight line with the 2 1000 w air cooled fixtures, then stay ceiling height and continue w/exhaust? 

passive intake, light , light ,fan ,carbon filter, exhaust into 2nd room to help heat my house in the winter? I have an elicent 8" fan, and am buying 8" ductwork. My intake has to be bigger, so I need 10" at the intake, then reduce to the 8" light fixtures?


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## MediMary (Feb 1, 2011)

Grab a canfan for the win! I find they work better pulling than pushing though.


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