Push or Pull through hood

Hotrod maybe I should have just said , think of this so your Knuck there has round valves and seats , what if the cylinders walls were rectangle.

jrainman said:

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 .

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OK now THAT makes sense. Assholes that call people names because they "Know" something but don't know fucking why are are . . well . . . assholes. A la Matias the dick. His silly ass is repeating shit he hears but he doesn't know why. At least I can hypothesize intelligently and with experience while he simply runs off at the mouth. His parents had an idiot for a son.
If he does know it he's too dense to express it - either way. Another punkass kid with a little brain and a big yapper.

Thank you and +rep for you.

ONE person here can EXPLAIN - not just pass of shit because somebody else said it. That doesn't make it so. If you can argue a point then do it. If your point can be covered with a hat then do that.

really thing to do is go to a HVAC forum with a venting question , Its like taking your car to the ZOO to get fixed when you ask a venting question here, I get caught up on these questions by the replys I read and feel sorry for the person getting such bad answers. when Im here to learn how to grow , not teach HVAC. I need to stick to my reason for being here.

jrainman said:

really thing to do is go to a HVAC forum with a venting question , Its like taking your car to the ZOO to get fixed when you ask a venting question here, I get caught up on these questions by the replys I read and feel sorry for the person getting such bad answers. when Im here to learn how to grow , not teach HVAC. I need to stick to my reason for being here.

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Like hell! You are JUST what is needed here. Stick around - you'll see. See my answers about air? I at least have some background to try to reason. Many here are frigging mynah birds - they squawk and repeat it because they heard it. Not because they know what they are saying. Thanks again and you will be busy I am sure.

From my personal experience...I've always pushed air through hoods. Mainly because it keeps from smelly air being sucked through the seals on the hoods into the ventilation system. but i was running a sealed room.

phishtank, sealed room as in dual fan room ? one for hood and one for cab ?

this is my current setup for both my tents. 440cfm fan (outside tent)--duct--tent--duct--hood (air flow over socket then bulb)--duct--tent--duct. fan is sucking in cool basement air. this setup will be the same for my veg tent and my flower tent. for the scrubber the fan will be inside the tent (440cfm fan--duct--tent--duct--massive carbon scrubber (6" inlet 8"x24" w/125oz of activated charcoal inside).

IF the temps dont seem to be under controll, ill switch the fan around and try pulling the air vs pushing the air. however, with a 440cfm fan for a/c hood cooling, i doubt heat will going to be an issue at all. the fans (hood fans only not the scrubber fan) will aslo be on a digital temperature controlled on/off switch.

im hoping for a newb grower i have that correctly routed. after ALOT of reading and asking questions it seems either way (push or pull) will work. my grow is still a work in progress.

DemonTrich said:

this is my current setup for both my tents. 440cfm fan (outside tent)--duct--tent--duct--hood (air flow over socket then bulb)--duct--tent--duct. fan is sucking in cool basement air. this setup will be the same for my veg tent and my flower tent. for the scrubber the fan will be inside the tent (440cfm fan--duct--tent--duct--massive carbon scrubber (6" inlet 8"x24" w/125oz of activated charcoal inside).

IF the temps dont seem to be under controll, ill switch the fan around and try pulling the air vs pushing the air. however, with a 440cfm fan for a/c hood cooling, i doubt heat will going to be an issue at all. the fans (hood fans only not the scrubber fan) will aslo be on a digital temperature controlled on/off switch.

im hoping for a newb grower i have that correctly routed. after ALOT of reading and asking questions it seems either way (push or pull) will work.

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I agree. We aren't trying to win the NHRA nationals here. Just trying to move air across a heated space to attempt to cool the immediate area. The two major culprits in premature equipment failure are HEAT and VIBRATION! By working to eliminate these two factors we extend the service life and maintain more function in our gear. I reason placing the fan where the bearings stay the coolest will keep the fan running quiter, longer and more efficiently. That's just me and the HVAC guy above clearly explains the turbulence encountered doing it with the push method.

hotrodharley, your right that yes you will allow your fan to last longer if you pushing the air, im just concerned about how much cfm will be pushed out the other end ?

I mean you saying it does work i believe that but what is the airflow like ? Would you suggest another fan at the end of the duct to ensure optimal flow rates ?

a 440 cfm fan should be able to push air thru 2 hoods if need be. i mean your only moving air inside a 6" diameter opening covering about 10' max (10'max is a guesstimate including dust work and such).

Plant Whisperer said:

hotrodharley, your right that yes you will allow your fan to last longer if you pushing the air, im just concerned about how much cfm will be pushed out the other end ?

I mean you saying it does work i believe that but what is the airflow like ? Would you suggest another fan at the end of the duct to ensure optimal flow rates ?

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Personally I would add a smaller booster fan on the FAR end of the run to assist the larger fan. And the HVAC guy did point out why they work better doing the stupid, leading me to ask why these fans are designed this way? I just feel it's mechanically inefficient at best to try to use a smaller fan to move air from a larger volume. Just me and the HVAC guy might explain. I do appreciate his understanding and his explanations. Plus I have this thing about money. I don't like wasting it or spending it on something when I can do better.

also forgot to add this. ill have 1 duct booster fan 280cfm intake in the flower room, and 2 in the veg room (intake down low, exhaust up top), plus a 16" adjustable oscillating fan in each room for optimal air circulation and stem/root strenghtening.

To the HVAC man - you can see a future product line here can't you? Round hoods that are not cooltubes to match round fans and fittings? Or cooltube-type inserts in the hood without the reflective portion to allow all the light but to limit the space it can heat quickly and aid air flow.

I use my fans to push as intended and then I use cheap boosters on the opposite end of the line

If the inlet and outlet of a fan are the same shape and are equal diameter it can push or pull. Nothing in the design of these fans in the cans would force you to use as an exhaust fan. NOW, if one side is tapered or curved or shaped to force the air into a smaller volume and hence speed it up BEFORE it passes over/through the blades THEN that might make a difference. In those straight cans? IT DOES NOT MATTER WHICH SIDE!!! I'm awaiting Matias the Genius and his pinheaded response.

Otherwise I tend to try to save my money by not abusing my gear. Pot growing gear, motorcycle tools, carpenter's tools - whatever. I take care of it and it takes care of me.

I have a 6" Hydrofarm on a 600w cool tube and they (Hydrofarm) told me it does not make any difference whether the fan pushes or pulls. I have it set up to pull because of the physical configuration of my grow room (2 walls are concrete) and the availability of another power circuit. To push I would have to put the fan in the grow room or run a bunch more ducting, neither of which I want to do.

I would suggest pushing the air through your lights for one main reason. If your hoods are not completely sealed you could be sucking smelly air through any cracks or gaps in your hoods. If you push the air through your lights, hot air might leak out but i'd rather have that happen then to exhaust smelly air.

Wow this became a heated argument fast! Ha ha, I bought a hurricane 6 in because I needed something to push or pull inline air, in any configuration, through two or more rooms.
This is the desisignated platform for which these "fans" are desighned. They are not blowers designed to direct air one direction without burning up bearings.
So my question is this, Why not use it like I have? I draw air through a couple of xxxls, put the air through the wall pushing it through two more 1000 watt yield masters, loop it back through the wall at the far end of the veg room. Put it through a deverter, then most exaust goes out through a necked down, 4 in line run 15 feet to slow it. into a y at the wall, This splits and pressurizes the dryer with warm air. (Speeds up drying time when we do wash!) And out the outside drer vent. The deverted air feeds down a small 4 in duct and meets another Y. its flipped with a long 6 in tail to the floor. Also coming from the veg is a short 4 foot 6 in. It necks down to 4 in on the deverter side "see pics". duct hose it hangs over the veg table the positive flow from exess hurricane air in deverter. draws warm air from ceiling level into bloom room. A four inch blower necked up from 4 in to 6 in supplies both rooms with fresh air, veg room first then sucked in by the deverter to the bloom room picked up by the back end of xxxl 1, run through xxxl 2, through the wall, through the two light's back through the wall, then deverter half goes out the dryer vent. Get it. My temps are perfect always bloom gets cooler quick when light go out. veg drops about 3 deg for those 12 hrs. I see or more telling no drag difrence in the way that the fan sounds. This is because as I "Tuned" The deverter this is the sound I was looking for. When the little hum stopped and there was just a small amount going into the bloom the fan went back to silent. I temped my casing and mine only reads 81.4 and it has been running straight for 3 weeks without bieng shut off ever. So Guess We will find out. The warranty is for five years and these fans are built for pushing or pulling, so you can't void your warrenty by using it in either way, or both at the same time. Hope this helps. melungeonman.

Done both. Pulling burnt out my bearings I had to buy more from ebay. Turns out they're only rated at 180 degrees F. While I have an IR thermometer the cool tube glass is at 210F I'm sure the lamp is much hotter. So now I use a fan like it was designed for and that is to push air.

Also, as blaze stated when you are pulling air you better hope you have every leaked sealed. Pushing will just push hot air back in the tent which I'm ok with.

btw the temp at the plant is 73.