Ventalation: fans fans fans fans...?

Here's the deal: I have this closet for my flowering section and everything was fine until i switched from 400W to 600W. I just can't seem to get the temp down where it needs to be. My crops keep coming out a little brown from the heat, and sometimes a couple plants even die. Today I bought another fan, 6" about 270 CFM.

My question is where do I place my inline fans in the run of cooling ducts? There seems to be a great difference of opinion as to wether you should push or pull air through a cool tube or sealed hood. If I remember right, I think it was Zandor who said you should always push the air over the lamp. However I have read many times that you should have your fan after the lamp so it is pulled over it. And where in the run should I put the fans? Right near the light? At the beginning of the run? At the end? Middle?

Arrrgh! At this point I am ready to tear appart my settup and do it over once again. I want to be darn sure that I get it right this time. Oh yeah, I don't know if it makes any difference, but I have a CO2 generator. My 4" run is about 18 or 20 feet total. I plan to use the fan that I bought today, and a 4" fan, about 175 CFM. I am pretty sure I have enough sucking/blowing power now. My intake is near the floor in a differnt room which stays about 81 degrees in the summer. The run before the lamp(which is in a sealed hood), is about 6 feet, and the rest is of course is after the lamp which exhausts to the outdoors. There are two 90 degree bends before the lamp and two after. Please don't tell me I need the entire run to be 6", because the area of the intake will not allow it.

My initial thought on this to put the 6" fan right before the light, and the 4" inch fan near the exhaust opening. Any thoughts on this would be greatly appreciated, especially by HVAC experts.

how high is high temps?

with CO temps can usually run a little higher

In the middle it sometimes reaches 92. I have my light almost 2 feet away, and I would like it if I didn't have to pull it back even further.

My co2 is not set up yet. I have the generator installed, but I can't decide yet how to control it.

usually you would like to keep the exhaust lines as straight as possible i run 2 600's and pull the air across them using fresh air (from on opening of the grow tent to the other) i keep my fan at the end of the run 265 inline and exhaust out the top with a 465 cfm this keeps my whole hut at about 78-80

u may need to invest in a small air conditioner with those 92 degree temps!! lol.

6in ducting would be the way. i would place the run all the top of closet and to keep 90 degree angles out and just place a home made stand for the plants to set up on

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Originally Posted by Forwhat420

i keep my fan at the end of the run 265 inline and exhaust out the top with a 465 cfm

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Darn! does this mean I have to take back my fan and buy bigger ones? And I figured out how I can eliminate one bend.

I acutally thought about tearing apart my old room air conditioner, and somehow puttting it in the duct line. Then there would be no problem keeping that bulb cool. Has anyone ever heard of someone doing something like this?

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Originally Posted by Forwhat420

6in ducting would be the way. i would place the run all the top of closet and to keep 90 degree angles out and just place a home made stand for the plants to set up on

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I'm not quite pictureing this. How can I bring air in from a different room, and exaust it out the side of the house, while having no 90's?

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Originally Posted by Forwhat420

a home made stand for the plants to set up on

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Please clarify. I'm in hydro with a recirculating hybrid drip/spray thingee. Does this matter for the stand?

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Originally Posted by Opie Yutts

I'm not quite pictureing this. How can I bring air in from a different room, and exaust it out the side of the house, while having no 90's?

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OK, I'm seeing it now. duh. But just going straight through the wall on the bottom and straight out the top is not possible for my set up. For one thing, my plants are above the cloning area and ballests and stuff.

well only if u can set the stand up. maybe not invest in bigger fan if u can get those bends out cuts ur cfm down to less than half of the rating of fan. u say that u have a room in the 80s? can u some how create an intake at the top of ur room to run across your lights out the other side of your room? you could use air conditioner vent covers to look inconspicuous and do u vent to the outside of your house? then use ur other fan to concentrate on pulling more air into the room from the 81 degree room?

if u can set the hydro set up on a stand i mean. i dont know about taking the air conditoner apart but if u know how go for it. sry keep posting back to back but thought process is a little corrupt right now

Opie - This thread is really confusing. From what I can understand, you are talking here only about the ducting, fans etc. that cool your light. Is that correct?

Below is a pic of my lights and vent. I suck air through two cool tubes using a 6" fan that then exhausts through a charcoal filter. (Suck or push seems to be a constant debate here, with no real consensus except that some applications may require one or the other.)

Anyway, I am sucking the grow room air through my lights, thereby pulling fresh outside air into the grow room. It seems to me that, if your ambient outside temps are around 81, you want to get as much of that 81 air into the grow room as possible, not just pass it through your light. So, for now, lose the intake duct and just suck air from the grow room and let the fresh air get into your grow room from the hole you were using for the intake duct.

All of that being said, once you start using co2, you need to keep the room sealed, but you can also get away with higher temps. However, for the time being, using your light venting to also vent the room should pull your temps down and is a very simple task.

I hope this helps. :thumbsup:

PC :smokin:

i dont have experience with a 600watt. but dont you need a bigger fan than 270 cfm to cool that down correctly?

also: there seems to be a lot of bends in your ducting. a lot of air flow is lost during extreme angles......is there anyways to cut all that other curbed ducting out of your setup?

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Originally Posted by keeko

also: there seems to be a lot of bends in your ducting. a lot of air flow is lost during extreme angles......is there anyways to cut all that other curbed ducting out of your setup?

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This is very true! the less bends the better. makes a huge diffrence. :)

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Originally Posted by PharmaCan

for the time being, using your light venting to also vent the room should pull your temps down and is a very simple task.

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That makes a lot of sense, and sorry for the confusion.

I guess I just wanted to know where in an 18 foot run of duct that has a light in the middle of the run, would you place a 275 cfm and a 175 cfm fan to get the best cooling possible. Forget all that other stuff, if someone could just answer that it would be great.

Your recomendation is actually the first thing I tried years ago, and it didn't work, probably because I didn't have enough total cfm, and I was using a carbon scrubber inside a pre-filter. I only want to redo my closet one last time, and I need to consider the co2. My ducts are behind a wall! As you probably already know, you can't use co2 while you are exhausting and intaking air, or it will be a complete waste. And using 600w in a small space makes it heat up almost instantly, allowing no time for co2. Therefore I guess I decided that I need two intakes and exhausts, one each for the light and one each for the room. That way I can turn off the room exhaust for a few minutes every hour or so, and run the co2 generator until it gets too hot again. The cooler I can keep the lighting duct run, the longer I can have co2 in the room, and the bigger my buds will be (at least I think that's the goal here).

Keeko, you are probably right about 270 not being enough cfm, and I was trying to get away with 175 cfm. That's why I am thinking of putting the 270 just before the light, and the 175 at the very end of the run.

This really sucks. So in order for me to have co2, I'm going to end up with 5 fans, just in the flowering section. The two mentioned above for the light, one room intake with a 4" 175cfm, one room exauhst with carbon scrubber about 320 cfm, and one oscillating fan gently moving air around the top of the plants. Oh well, at least the whole set-up in the veg section, including cool tube, works great with one 8" fan.

I believe it was Latewood, a year ago or so, who said cool tubes are great if you don't mind the $500 for fans that you need.

There were a couple posts today by a "SpaceNeedle". Hunt him down and rattle his cage. He's a heating and A/C guy and should be able to answer your questions.

PC :jointsmile:

Pharmacan, I apologize for getting off-subject, but I would like to know what that 'quilted' reflective material is in your cabinet pics ?? :smokin:

Reaper i also use it. Its designed to be put behind radiators to reflect the heat in houses, comes on a roll and its quite thick. Over here you can get in most general hardware stores but its not cheap for the amount you get.

OK, thank you ... I see it in photos occasionally, looks a lot more durable than regular Mylar ... :smokin:

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Originally Posted by the image reaper

Pharmacan, I apologize for getting off-subject, but I would like to know what that 'quilted' reflective material is in your cabinet pics ?? :smokin:

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Reaper - It's two layers of a mylar-like material with bubble wrap type stuff in between the layers.

Here's a link: http://www.bghydro.com/BGH/itemdesc....%2F025&eq=&Tp=

PC :thumbsup:

i use that stuff to...works great, just a pain in the ass to put up, it sorta holds its shape...

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Originally Posted by PharmaCan

Reaper - It's two layers of a mylar-like material with bubble wrap type stuff in between the layers.

Here's a link: Astro Foil - 4' wide - 25' roll | Mylar/Reflective Coverings

PC :thumbsup:

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Thank You :thumbsup: ... I bet that's the same stuff I was supposed to examine at Home Depot the other day, but couldn't find it ... now, I'll know what to look for ... :smokin:

thanks, from that info, I found the manufacturer, then found some retailers ... here's one distributor with several cheaper options Insulation 4 LESS ... :smokin:

Hey, no highjacking my thread. Just kidding. I was interested in that material too.

If anyone is intersted in how the ventilation portion of this thread turned out, or just to get some really good insight from a proffesional venting guy, go to this thread:

http://boards.cannabis.com/indoor-gr...-question.html

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Originally Posted by Opie Yutts

Hey, no highjacking my thread. Just kidding. I was interested in that material too.

http://boards.cannabis.com/indoor-gr...-question.html

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Give it up, Dude, you've been jacked. :D

Thanks for the rep, btw. We need to snag SpaceNeedle and get him hooked on the forum. I don't think there's any other hvac guys/gals posting right now.

Reaper - They have all kinds of interesting/unusual insulation on that website. Thanks for the link! :thumbsup:

PC :stoned:

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Originally Posted by the image reaper

thanks, from that info, I found the manufacturer, then found some retailers ... here's one distributor with several cheaper options Insulation 4 LESS ... :smokin:

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Great find! :)

Take a look at my system, three vents 40w for one 250w HPS,
http://boards.cannabis.com/closet-ca...ml#post1512807