4 x 8 grow tent cooling problem

I am trying to figure out how to cool 2 1000 watt HPS grow lights with ballasts out side the room one is a cool tube hooked up to a 6" fan and carbon scrubber the other is a large hood with glass bottom with 2 pc fans and a 6" duct booster hooked to the cool tube my temps are running way to high 99-102 degree's no CO2 at this time it's 35 degrees outside and i have a pc fan drawing in air from a 4" duct any suggestions? I have 12 plants that are to big to veg and need to get them in bloom but these temps will kill them.....PLEASE help money is tight but if there is no other way I will spend it...

minimum you need bigger fans and to get some more outside air into the grow area. you might want to buy a bigger inline fan for your room and use the 6" inline to enclose and duct the lamps, drawing cool air from outside to more efficiently cool the lights. then exhausting it well away from the grow space. if you have high summer temps you may consider getting an A/C to control temps.

Thanks for the fast reply so run a closed duct for the lights with one end sucking out side and one end blowing out side and then have another one sucking air from room and venting it out doors and the last line coming in again?

would it help to vent lights separately? 2 separate fans and exits?

jojo091705 said:

Thanks for the fast reply so run a closed duct for the lights with one end sucking out side and one end blowing out side and then have another one sucking air from room and venting it out doors and the last line coming in again?

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Vent your lights on their own line if you have enough holes, which you should on a tent. Then you can set up another intake and exhaust to try and deal with the temps. I would recommend putting your most powerful fan on the lights as that will remove the most heat. You may also need to run the exhaust tube from your lights to another room or outside or the air for your other intake will be too hot and ineffecitve.

2000k in a 4x8 tent is ambitious and if you can master that dance those lights will give you unbelievable buds! I recently went from 2 low powered inline fans on my lights to a very high powered fan and it changed my whole room. I've had to turn the AC UP a couple degrees!

A 6" 440 cfm fan should be fine for exhausting the lights. Can you draw from the outside? Ideally this is what I would do - pull from outside through lights and exhaust either outside or into your home venting - cheap heating and this air shouldn't smell. Have a second smaller fan pulling through a filter and out of the tent with a passive intake taking air from the outside.

Thanks guys! Gastanker do you believe that setup would properly remove the heat from 2 1000 watters?

Taking the carbon filter off your light venting should decrease your temp significantly.

Gastanker said:

A 6" 440 cfm fan should be fine for exhausting the lights. Can you draw from the outside? Ideally this is what I would do - pull from outside through lights and exhaust either outside or into your home venting - cheap heating and this air shouldn't smell. Have a second smaller fan pulling through a filter and out of the tent with a passive intake taking air from the outside.

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This set up would take the hot air from one light and compound it on top of the heat from the other light making the cooling of the second light inline inefficient. The idea of this drawing/diagram is spot on, but maybe use "Y" ducting splitters and a stronger centrifugal fan (Not sure if you are running centrifugal or just ordinary inline fan) to isolate each light separately. Also as mentioned make sure you duct out in a different area that your ducting in, no point spitting hot air out only to have it sucked back in.

if you have a strong enough fan and the air is cool to begin with, the heat shouldn't compound. the Y set up would probably cool more efficiently but i dont think it would make much difference in this case.

DrunkUncleHarold said:

This set up would take the hot air from one light and compound it on top of the heat from the other light making the cooling of the second light inline inefficient. The idea of this drawing/diagram is spot on, but maybe use "Y" ducting splitters and a stronger centrifugal fan (Not sure if you are running centrifugal or just ordinary inline fan) to isolate each light separately. Also as mentioned make sure you duct out in a different area that your ducting in, no point spitting hot air out only to have it sucked back in.

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I vented a 4x8 with 2 1kW lights with a 440 CFM fan running at half speed. If you are pulling 35 degree air through those two lights at 440 CFM there is no way either will get hot - I would estimate the air coming out to be 10 degrees hotter max. If this 45 degree air is vented back outside or into your house's venting system it would never return and ambient temps would never increase. To be honest if you also had the tent pulling in 35 degree air at 220 cfm you might need to put a dimmer on one of the systems to maintain heat and not run too cool.

DrunkUncleHarold is spot on with that light cooling pic.
No "Y" connectors or bends if you can avoid it.
Just ONE 30 degree bend will drop you fans cfm's by roughly 10%, not to mention a 45 or 90 (subtract 30% of cfm's) degree bend !!
So keep it straight like in the pic.
The TYPE of ducting also plays a BIG role in cooling !
Flexible-soft, rigid, semi-rigid, etc...
For instance, a house is only allowed 25ft of dryer ducting for fire reasons.
If the builder adds a 45 degree elbow, he HAS to subtract 2.5 ft from the mandatory 25ft for EACH elbow.
It's minus 5 feet for EACH 90 degree bend.
This is to protect the home due to the severe air flow restrictions that the bends cause.

BUT, that filter on the floor is a no-no !
Heat and the smell will rise to the top of the tent, so the scrubber should be as high as possible.
Keep it on the same side as in the pic, but raise to the top instead.
Plus you'll get a nice mix/current of fresh air throughout your tent as a result too, but not with the scrubber on the floor.

^ Yeah forgot to mention to put the filter at the top. Drew it down low out of ease but he it totally correct about putting it at the top where the warmest stinkiest air is.