cool tube ? extraction

[Gruffy]

Hey guys n gals ..
I am gonna buy a cool tube for my setup .. what fan would i need to sufficiently cool a 400w hps light ? and would the fan be pushing the hot air out of the tube or sucking it ..in other words does the fan go before or after the light .. im having a dumb moment and i reckon its extraction hence why they are called extraction fans lol i just need someone to verify lol regards :)

hope someone answers :)

[Gruffy]

I am on a budget, would this be sufficient
:SystemAir RVK extractor fan capable of moving 175m3/hr

Regards :)

[Weedhound]

i had an inline 270 cfm that cooled a one 1km hps very well and I would suggest at least that in case you want to use it for a larger wattage later. Can't really say about the one you are talking about because I just don't know enough about fans in general.

In the case of only one fan....it should ALWAYS pull rather than push air.....in other words....it goes AFTER the fan. ;)

[Gruffy]

cheers for clearing my dumb moment up mate :P ye i thought it was after the fan :) if you used a 270cfm to cool a 1000w i think a 175m3/hr shud be efficient to cool a 400w .. i dont plan on upgrading as i dont need that much power lol :)

thanks for the reply matey :)

[Opie Yutts]

Your question can't really be answered with that amount of info. Is the fan right next to the light with a couple feet of ducting? Are you using coiled dryer duct, or actual smooth ducting material. How many 90 degree bends, how many 45's or 30's? Any T's or Y's? If so how many? How long is the run of ducts total? Are you exhausting back into the grow area or does will the light have a dedicated fan and run of ducts? About 325 cfm.

[gainesvillegreen]

I am on a budget, would this be sufficient
:SystemAir RVK extractor fan capable of moving 175m3/hr

Regards :)



Well, each 1m^3 is about 27ft^3, 175m^3/hr would be equal to about 4725ft^3/hr, or only about 79cfm. I would say that this fan is not suited to properly exhaust any HID light fixture. Especially when you factor in the ducting like Opie said, the actual airflow would drop to just about nothing.

I know you said you're on a budget but just remember that this fan will cool your light, make the light last longer, make the room cooler, make your plants cooler, and allow you to place your plants closer to the light (more lumens = more yield)... my point is, proper ventilation is key for premium product.

[Opie Yutts]

For HID lighting, you need to spend as much on venting as you do lighting. Or you'll be sorry.

Just stick with cfl.

[805dnbhead]

yo, i think theres a miscommunication going on here. i think dude was trying to tell you the fan should come after the light. not the fan should come after the fan, which is what he typed, but not i think what he meant! i'm a first time grower, so my 2 cents are worth just that, but i have a cool tube with a 600 watt bulb and ballast. i was putting the fan before the light (pushing) and getting temps in the high 90's for the first few days, then just did a damn google search and connected the intake from the fan, to the cooltube, with duct, and no angles between the fan and tube. the intake is inside the room with the exhaust blowing directly out with as few angles as possible. i found out why they call it a cooltube. temps never get above low 80's and i live in a very warm area.


QUOTE=Gruffy;1810713]cheers for clearing my dumb moment up mate :P ye i thought it was after the fan :) if you used a 270cfm to cool a 1000w i think a 175m3/hr shud be efficient to cool a 400w .. i dont plan on upgrading as i dont need that much power lol :)

thanks for the reply matey :)
[/QUOTE]

[Gruffy]

Hey guys thanks for the replies :)

I can spend a bit more on a better fan now, As i wanted to spend £100 - £120 maximum combined for the ventilation and the cool tube but i just won a cool tube on eBay for £21 delivered which was nice :) so i can spend a bit more on a fan :)

Also i understand the whole fan thing, I plan to put it about 1-2ft after the light so it should work pretty well :)

i only have a small space to work with at the moment so i agree i need to splash out on buying decent ventilation.

Thanks for the help :)

[gainesvillegreen]

Most fans you will find for this application do better sucking or pulling air than they do blowing or pushing. Inlines are the best as they are more efficient, quieter, etc., and also pull air better. This means you will want the fan to be at the very end of the exhaust side, pulling air through a filter, then your cooltube, then ducting (as little as possible), and then to the fan and exhausted.

air flow---->filter--->cooltube-------------------------------------->fan-->exhausted

[Gruffy]

why do u need a filter before the cooltube ? just curios as i wasnt gonna bother lol :P


Most fans you will find for this application do better sucking or pulling air than they do blowing or pushing. Inlines are the best as they are more efficient, quieter, etc., and also pull air better. This means you will want the fan to be at the very end of the exhaust side, pulling air through a filter, then your cooltube, then ducting (as little as possible), and then to the fan and exhausted.

air flow---->filter--->cooltube-------------------------------------->fan-->exhausted

[Opie Yutts]

Most fans you will find for this application do better sucking or pulling air than they do blowing or pushing.

I've heard this from several people. Does anyone know the physics behind this?

Also, I'm pretty sure 2 fans would be better than 1, especially in longer runs. If I had a bigger one and a smaller one, would it go like this?

intake>smaller fan>cool tube>carbon scrubber>bigger fan>exhaust

Or I guess, depending on how closely matched the two fans are, it might be better to just leave out the smallest one. Anyone? And where's the cut off point? At what % difference would it be best to just leave it out. If it can't keep up, it would just hinder air flow. Would the two fans need to be the same? And why are those sheep up in the trees?

[Gruffy]

i was thinking

intake>cool tube>fan>exhaust

im only a hobby grower and i have 3 plants i would have thought one decent fan would be sufficient to withdraw enough hot air too keep my 400w light cool enough.

i think we need someone with some experience to comment here possibly some pics of their setup ? :stoned:

[Opie Yutts]

What we need is an HVAC guy, or else we need to look up the formulas on the web and do some calculations. Naaa, too much work.

[FourOneNine]

Obviously, it would be better suited to have the carbon scrubber at the complete end.

(passive intake)-->Cooltube-->Fan-->Carbon Scrubber--> AIR

Construction should vary mostly on CFM of the fan.

I run a 400W MH, on A OPEN reflector. 6inch Duct connect to fan then scrubber, I get 82F.. But my fan is 400+ CFM so I dont need any take holes, air gets pulled from cracks around the cab. My friends seldom wonder why Smoke gets sucked into my closet.

[gainesvillegreen]

Obviously, it would be better suited to have the carbon scrubber at the complete end.

(passive intake)-->Cooltube-->Fan-->Carbon Scrubber--> AIR

Construction should vary mostly on CFM of the fan.

I run a 400W MH, on A OPEN reflector. 6inch Duct connect to fan then scrubber, I get 82F.. But my fan is 400+ CFM so I dont need any take holes, air gets pulled from cracks around the cab. My friends seldom wonder why Smoke gets sucked into my closet.

I would like to know the reason why "obviously, it would be better to have the carbon scrubber at the complete end".

Most setups I have ever seen had the scrubber-->light-->ducting-->fan-->exhaust. Because fans suck better than blow, forcing a fan to blow against the filter will diminish the volume of air flowing.

I'm guessing you could find supporting info either way, but this (http://www.bghydro.com/BGH/static/articles/0606_vent.asp) page talks about it at the bottom.

[xcrispi]

I tried cooling my cooltubes both ways . Pushing and Pulling air through them . I went as far as checking surface temps of the glass w/ a hand held laser temp gun too. They were significantly cooler w/ air being pulled through them .

I also tried Opies theroy - 1 pushing and 1 pulling and the 1 pushing air was a restriction = temps went up .

We now have 3 -1000w. hps. inline cooled by a 630 cfm hurricane blower now and the 10 by 12 foot room doesn't get over 82 degrees . Here's a pic. w/ just 2000w .
Peace
Crispi :jointsmile:

[CashandPrizes]

im gettin ready to upgrade to cool tube hoods.

this might be a dumb question but all i have to do is plumb them into my main exhuast fan?

for some reason i thought there was a little fan built into the end of the hood were the duct starts?

[Opie Yutts]

I would like to know the reason why "obviously, it would be better to have the carbon scrubber at the complete end".


I was wondering the same thing.

[Opie Yutts]

forcing a fan to blow against the filter will diminish the volume of air flowing.

Yeah but so does sucking through a filter. Theoretically, wouldn't it take the same amount of force to go through something one way as it does the other, not counting diodes and stuff?

[Opie Yutts]

I tried cooling my cooltubes both ways... ...They were significantly cooler w/ air being pulled through them.


Well then, I guess there it is. I'll take actual examples over theories any day. Thanks.

[Opie Yutts]

for some reason i thought there was a little fan built into the end of the hood were the duct starts?

Nope.

And yeah, just plumb them into your ducting, somewhere before the fan.

[CashandPrizes]

well then upgrade here i come! :thumbsup: