Push or Pull through hood

Pulling drags more air acrossed the light more efficiently rather than pushing! it may make the fan work harder, only downside

chewberto said:

Pulling drags more air acrossed the light more efficiently rather than pushing! it may make the fan work harder, only downside

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I respectfully disagree. The resistance is the same.

thinn said:

Does it really matter? There really is no proof or any study that i have seen to prove either or is better, i say do it how you like. All Equipment will fail and you should have the dough to replace any of it as soon as it does. I pull air thru my filter and push thru the hood in the same line.

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I would say pulling the air through would be better. Only because in doing so it puts a vaccum on your glass eliminating a leak through the seal. My xxxls do leak quite a bit when pressurized I was forced to put a second strip of foam on the hood to keep it from leaking. The only real downside to pulling it thru would be slightly higher operating temps IMO.

I would pull the air through mine but building limitations prevent this for me.

What is a duplicate thread?

...... Wut

pulling air you risk pulling in dank smelling air from any possible leaks in lines or seals, not wise in my neighborhood for certain. Keeping lines and hoods pressurized positive prevents any room air from being sucked into unfiltered hood line. I use a seperate blower to pull thru a carbon filter and exit dank co2 enriched air several times a day.

don't know about your rooms set up but mine is set up to pull air from my room and light into my carbon filter for smell and heat control..there are these little pieces of paper that come with your fans that will say INSTRUCTIONS start there... good luck and KEEP ON GROWIN...

It's simple do what works for you and the space you have I pull from filter to last hood then push out the rest but I'm 4x4 in space

i went through various methods testing this, for cooltubes i pushed as they are completely airtight tubes, but they are sh1te imho i ran 3 x600 and yielded less than 2x600 magnum xxxl's, for hoods like these i pull the air, pushing created a rise in temps of around 5c as oppose to pulling. with the shape of the hoods being large sqaure you find air not passing thru the hood as quick and blowing through any leake you may have, and with a hood you will have leaks,

my fan has a 5yr warranty, i don't think breaking should be a big deal if i get 5yrs to get a new one that's more thank worth it. i pull and have it in the room to make neg pressure, make sure everything stays in unless its been scrubbed

So pulling is not recommended for people who really have a issue with smell getting through?

What do you guys say about using a pre-foam a/c filter for the light ? protecting it from any dust or bugs etc ?

Try sucking a drink through a narrow straw at the top that is wide at the bottom. See how thirsty you stay or how long it takes you to empty the drink.

Try doing the reverse. See why it is easier to install a fan on the cool side of your light, since you aren't narrowing that, and push that air through a wide straw that then narrows down rather than the reverse.

Looking at it like benchflowing heads or figuring exhaust pipe length and configuration. Plus the lack of heated air over your fan has to make the bearings last longer. Alternator bearings usually last longer than those on the shafts of turbochargers.

Better yet, post pics of racers with the turbos and the superchargers on the frigging exhaust side, eh? Then try to explain why a frigging simple fan system should be setup differently than all other mechanical applications. Some of you need to stick to advising on pot. Just because the fan CAN pull air through doesn't mean it should or it can't work far better. But run hot air through and then be back "Help my fucking fan is noisy".

I am a newbi in growing, only know about 20% of what I need to learn that is why im here to Learn from exp People, Soo dont take this to hard,But You guys dont no Jack Shit about eqimpment design and Air and how it moves ,let me put it this way, there is at least if not more to learn about air movement as there is in growing I have over 30 yrs HVAC design,Fab, and Istall, These are EXHAUST FANS and they are design to PULL the air ,can you push air with them Yes but you need to know how to properly SIZE the duct work to turn these fans in to WHAT is Called MAKE UP AIR , IVE Said this many times here AIR DOES NOT MOVE LIKE WATER, You need to Know Equal Friction Method and or Velocity- Reduction Method to properly Move AIR.

I see what you mean man, so if i push the air into a wide opening that narrows down it will be much better than the reverse , i get you there.

I will definately first try out how the temps operate with the fan pushing, it does make sense that in cars a turbo is attached to push air in, ill measure the temps and all seems okay i will carry on i only just might try pulling if i run into a temp problem.

The fan will probably last longer, maybe for some fans it wont make the biggest diff but for sumthing with a lower quality heat could just mess it up.

Thank you for your help though hotrodharley

Jrainman, seeing as you know alot about air extraction help me with my cab and calculating the cfm loss in the ducting : ) i have basic knowledge of growing and i could help you too ! peace man

wanted to give my two cents (mainly to disprove dickhead)...agree with you Joe, i use outside air to cool my lights and my main reason to pull the air, was to keep the fan noise as far away from the outside as possible. As to the temperature of the air, if you use outside air like me, its a non issue. In my opinion, if you use the proper fans and keep ducting smooth, the air moves through them so quickly that they dont have a chance to get extremely hot.

jrainman said:

I am a newbi in growing, only know about 20% of what I need to learn that is why im here to Learn from exp People, Soo dont take this to hard,But You guys dont no Jack Shit about eqimpment design and Air and how it moves ,let me put it this way, there is at least if not more to learn about air movement as there is in growing I have over 30 yrs HVAC design,Fab, and Istall, These are EXHAUST FANS and they are design to PULL the air ,can you push air with them Yes but you need to know how to properly SIZE the duct work to turn these fans in to WHAT is Called MAKE UP AIR , IVE Said this many times here AIR DOES NOT MOVE LIKE WATER, You need to Know Equal Friction Method and or Velocity- Reduction Method to properly Move AIR.

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So going from 6" to 4" past the hood doesn't make a venturi effect?

Matias420 said:

wanted to give my two cents (mainly to disprove dickhead)...agree with you Joe, i use outside air to cool my lights and my main reason to pull the air, was to keep the fan noise as far away from the outside as possible. As to the temperature of the air, if you use outside air like me, its a non issue. In my opinion, if you use the proper fans and keep ducting smooth, the air moves through them so quickly that they dont have a chance to get extremely hot.

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And dickhead would be who?

Hotrod , first off Nice Knuck if you are the caretaker of that Iron ,Much respect, Anyhow Yes it dose ,but the problem is the sq inches of the hood its self and shape , what will happen is when the air enters the hood the air hits the rectangle shape and unequal size and will roll inside and there for the venturi effect will be dimminished. Air easly takes on a roll effect when pushed through sq or rectangle shapes, air moves much more uniformed through round as it naturaly spirals .when you put air through the round the hit a odd shape as rectangle it will alway act almost like the ocean tide beating against the shorline .