# Help with exhaust!



## phatpharmer (Oct 30, 2008)

Hi guys I want to puchase a good exhaust fan but I'm not sure which one would be best for my situation I have a 10ftx10ftx8ft room, I would like alittle bigger than needed to be safe. So if someone can help with the size i would need that would help alot. And any web sites that sell them cheap would be nice to no as well( that ship to Canada) thanks again PP:hubba:


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## ms4ms (Oct 31, 2008)

greetings, I would suggest you go to htgsupply.com as they have a good selection with vortex fans and such. Scroll down to the bottom of the fan page and you will see the ones I use. They have 4 and 6 inch fans that do a good job and are not to loud. They are in the 20 dollar range. I have the 6 " in my room and it is to much. Hope this helps.


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## keyline (Oct 31, 2008)

phatpharmer said:
			
		

> Hi guys I want to puchase a good exhaust fan but I'm not sure which one would be best for my situation I have a 10ftx10ftx8ft room, I would like alittle bigger than needed to be safe. So if someone can help with the size i would need that would help alot. And any web sites that sell them cheap would be nice to no as well( that ship to Canada) thanks again PP:hubba:



Generally speaking, the size of fan you need, will largely depend on what you are trying to do with them.  For Example if you have 4 1000W HPS or MH lights in there, your answer would be a lot different if you were a couple of fluorescent tubes there.  In other words, you need to specify what your goal is.  Heat removal?  Air scrubber? or just moving air within your room....


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## greenfriend (Nov 1, 2008)

IMo you should clear the air in the growroom once a minute if not more.   For a 10x10x8 room, 800 cubic feet, you need an inline fan that moves 800 cfm or more.  My 6" inline fan moves about 450cfm so you will probably need a 10 or 12" fan.  These fans will probably cost at least $150-200 but imo its well worth it especially when running HID lights.  Also this amount of ventilation will keep the plants cool and get them plenty of Co2.  Good luck!


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## greenfriend (Nov 1, 2008)

Also what keyline said, i am setting up room now with 4 1000W HPS, so i bought a 6in inline for each lamp, plus a 10" inline for intake and a 12" inline for exhaust.  it'll be like a hurricane in there, but the plants will love it.  depends on the lights you are running


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## andy52 (Nov 1, 2008)

for an area that big i would go with an 8in can max fan.they are not real cheap,but you need something powerful for that size area.jmo


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## 4u2sm0ke (Nov 1, 2008)

be sure to get controlers on them as well..you will want to control the temps..JMO


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## keyline (Nov 1, 2008)

Well, I was in the heating ventilation and air condiitioning biz for about 10 yrs or so....
I really don't believe you need a 6" fan for each 1000w light... 

I can tell you that I set up a guy with 4 1000w hps and a 600 hps, with a scrubber the size of a 40 gal hot water tank using only one fan.  It was a 12" fan that sucked the the exhaust thru the scrubber and then I re-directed the clean air back thru the lights and then sent that air back to join the clean exhaust again.  The drawback is that the lights only work when the scrubber is on, plus the cleaned air is the temp of the room that's being re-directed  thru the lights.  But, he was very happy with it, because it saved him on fans as well as the noise of the fans running.  I do believe the temps would be 2 or 3 degrees lower if he used a separate fan bringing fresh COLD air in for the lights.  If anyone attempts this, however see me for particulars of the ducting so that air pressure isn't lost on this kind of system.


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## greenfriend (Nov 2, 2008)

keyline said:
			
		

> Well, I was in the heating ventilation and air condiitioning biz for about 10 yrs or so....
> I really don't believe you need a 6" fan for each 1000w light...



...unless you use A/C how do you suggest cooling this setup.  the lights already run during nitetime.  the room is 2000 cubic feet, so 3 6in inline and 1 12 in clear the air in the growroom every 40 seconds or so.  and i dont use Co2, so i like plenty of fresh air for the plants.


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## papabeach1 (Nov 2, 2008)

keyline said:
			
		

> Well, I was in the heating ventilation and air condiitioning biz for about 10 yrs or so....
> I really don't believe you need a 6" fan for each 1000w light...
> 
> I can tell you that I set up a guy with 4 1000w hps and a 600 hps, with a scrubber the size of a 40 gal hot water tank using only one fan.  It was a 12" fan that sucked the the exhaust thru the scrubber and then I re-directed the clean air back thru the lights and then sent that air back to join the clean exhaust again.  The drawback is that the lights only work when the scrubber is on, plus the cleaned air is the temp of the room that's being re-directed  thru the lights.  But, he was very happy with it, because it saved him on fans as well as the noise of the fans running.  I do believe the temps would be 2 or 3 degrees lower if he used a separate fan bringing fresh COLD air in for the lights.  If anyone attempts this, however see me for particulars of the ducting so that air pressure isn't lost on this kind of system.



4 of 1000 watt? oY....  and that method?   be careful.. either way..

but if one drop of water touches the bulb   then you gonna have nightmare..   IMO..you do need cool air to keep bulb cool... and plants can feel the "real sun" out of it..   just be careful.. I don't need four of 1000 watt myself..


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## keyline (Nov 2, 2008)

greenfriend said:
			
		

> ...unless you use A/C how do you suggest cooling this setup.  the lights already run during nitetime.  the room is 2000 cubic feet, so 3 6in inline and 1 12 in clear the air in the growroom every 40 seconds or so.  and i dont use Co2, so i like plenty of fresh air for the plants.



Well, I would use the 12" on your scrubber and exhaust it out.  The scrubber would be up as high as possible so that the warmer in the air leaves the room first.  You might consider hanging it horizontally from the ceiling.  I would use one 6" and hook up all four lights in a daisy chain and directly out. By bringing iin fresh air from the outside and running it thru all 4 lights and exhausting it out, you will not have to scrub that air as long as the lights are sealed with the glass in the lamps.   The other two 6" fans would bring in fresh air preferably at the height of the area between the  bottom of the light and the top of the plants.

I would also NOT use flexible pipe but rather hard pipe (warm air pipe)  wherever possible.... no hard bends, as air likes to go in the path of least resistance.  The only place where I would put the flexible pipe is by the lamps to keep them adjustable in the up and down position.


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## andy52 (Nov 2, 2008)

you will not vent 4 lights with a 6 in blower.period i have one 400 watt and it takes at least 430cfm blower to run from the scrubber,thru the reflector and out the top.and you will need an equal size to bring cool air in from the bottom.tried and true


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## keyline (Nov 2, 2008)

papabeach1 said:
			
		

> 4 of 1000 watt? oY....  and that method?   be careful.. either way..
> 
> but if one drop of water touches the bulb   then you gonna have nightmare..   IMO..you do need cool air to keep bulb cool... and plants can feel the "real sun" out of it..   just be careful.. I don't need four of 1000 watt myself..



When you are using the cleaned air and re-directing it back thru your lights, that temperature is perhaps 10 or 15 degrees warmer than the temp inside your growroom.  So if your growroom is say 75F, your exhaust might be about 90F.  So you are running the lights starting with 90F degree air,  somewhat warmer than normally.  I really don't understand your mention of a drop of water...?  where does the drop of water come from?  how would that happen in this sort of system compared to normal systems?

keyline


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## andy52 (Nov 2, 2008)

i think what he is saying is to not get spray on the bulb.also i have my can filter hanging with ducting going from it to one end of the reflecto,another piece of ducting on the other end of the reflector going to the blower,then another piece of ducting on the exhaust side of the blower going up and out of grow area to the outside.with a blower of same cfm drawing cool air from outside going into the bottom of the grow area.this has worked for me for some time.no problems and keep a 68 degree temp.


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## keyline (Nov 2, 2008)

andy52 said:
			
		

> i think what he is saying is to not get spray on the bulb.also i have my can filter hanging with ducting going from it to one end of the reflecto,another piece of ducting on the other end of the reflector going to the blower,then another piece of ducting on the exhaust side of the blower going up and out of grow area to the outside.with a blower of same cfm drawing cool air from outside going into the bottom of the grow area.this has worked for me for some time.no problems and keep a 68 degree temp.



That sounds excellent.  But that 68F, could be misleading.  For example if its summer time and the outside (cold) air being drawn in is 80F, there's no hope of getting the temp DOWN without A/C.   Then you need to figure out how much heat your lamps put out.  Four 1000W lights will put out  about 12,000 BTUs of heat.  You could compare that  with a small gas fireplace inside one small room where you are trying to grow and maintain temps.   I think you are doing well if you can maintain your room 10F above the ambient temperature that you are drawing in.   That means without A/C, if the air outside is 95 and you are using it to 'cool' your room, your temps can easily attain 105 or even 110F.  Of course that outside air temp is generally cooler at night, when most people prolly have their lights on.


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## keyline (Nov 2, 2008)

I should also mention that the ballasts ideally should not be in the grow room adding to the heat.  But even then, there is a lot of heat generated by the bulbs, and if its a vented 1000W light, you could probably fry an egg on top of the lamp.


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## JBonez (Nov 2, 2008)

ive got two 1000w lights, both being cooled by a 340 cfm inline fan. Ive got a flowering room 4x4x7 that has its own fan exhausting about 500cfm, it also has a passive intake to keep negative pressure and the light is cooled by ducting passing through the middle of the grow chamber. all in all it works pretty good.


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## keyline (Nov 2, 2008)

JBonez said:
			
		

> ive got two 1000w lights, both being cooled by a 340 cfm inline fan. Ive got a flowering room 4x4x7 that has its own fan exhausting about 500cfm, it also has a passive intake to keep negative pressure and the light is cooled by ducting passing through the middle of the grow chamber. all in all it works pretty good.



Nothing wrong with that! excellent!


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## NorCalHal (Nov 2, 2008)

A 6" can fan for every 1000w lite is WAY overkill. Wasting your $$.

To run 4000w, you can use a 6" for all 4. An eight inch is better, but if your lite flanges are only 6, then a 6" will work fine. 
To run a 6" on 4 lights, you will need to minimize the bends of the ductwork(use insulated ducting!!). Use 90dgree elbows for any bends off the lights.

In a 10x10 room, use a regular 10"can fan. Or get a CanMaxFan, but use a speed controller. Passive air intake.

I use a 6" can fan to cool my lights. 4 - 1000w's. I pull air from the room, thru a small carbon filter, thru the lights and exhaust out of the room. That plus a 8" can fan on a can 100 filter for exhaust. Passive air intake.

Bangin'.


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## greenfriend (Nov 2, 2008)

norcal what cfm rating do those can fans have? are they much different than inline fans.  the 6" inlines i have move about 450 cfm.  sounds like a can fan would be more powerful than an inline.  but if you have cooled 4 1000W with just those fans, i'll try that and cut down on the extra power.  musta worked for you cus your OG Kush was kick ***!


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