Why the @#$^ can't I get my temps down

[KnuckleHedd]

It sounds like you aren't air cooling the lights. My room is 11 x 12.5, not very different from yours and I run 4 1000 watt lights that are air cooled by a 8" Fantech. But, I don't try to run 4K in August. I stop around 1 June, start my seeds for the new season on 1 August. I begin with 1 1K light (my central ac helps, too) and add lights as the situation demands.

 

[tree d]

you need at least twice that CFM if your ambient is 80+.

I run 1 600w in a 4'x3'x'6' (~72 cu ft) and my fan pulls at least 600 cfm......in the summer I still struggle on really hot days to keep the temps under 90.

+ CFM = - temps

 

[FreezerBoy]

The intake from the basement air is in fact from under the door, however I figured the area of a 6 inch circle (pie r squared)

Exhaust area is π r². Intake is 2(π r²) If nothing else, you're choking the setup.

 

[dongle69]

I have also tried just leaving the flowering room door open during lights on in order to allow as much fresh air as possible into the room.

I don't think he is choking it if the door is open.
He needs more cfm or a proper a/c.

 

[baddru]

Why does the intake need to be twice the size of the exhaust?

 

[Hank Hemp]

With cool tubes vented hoods. I put it off and I'm sorry I did. If you can that would be your easiest option. IMHO

 

[TwinTurboGuy]

I see two possibilities.

Rule of thumb for passive intake is to use openings 3 times larger than the exhaust you're using. For example, if you use a 12' fan to pull air out, you need atleast 3 12inch holes for passive intake. Cab users go by this, but for a much bigger grow, I go a little overkill just to be on the safe side.

Another is how you did your ducting on your ventilation. Keep in mind that each bend on your ducting can drastically reduce the cfm and air flow. As a result, your fan works much harder and becomes more inefficient.

Just my two cents! Good Luck!

 

[Natagonnaworrie]

How about insulated ducting? Not sure if that even really helps or not. I assume that it would slow down the heating of the room for a few hours in the morning but eventually it would get up to the same temps if using non-insulated ducting. i'm dont know. Im planning to give it a try. every little bit helps.

 

[FreezerBoy]

Why does the intake need to be twice the size of the exhaust?

It doesn't need to be double it's just the easy fix. Think Venting for Dummies. If you want Venting for Smarties, look to Ventilation 101.

A single passive intake isn't capable of bringing in what a matching powered exhaust can move. It chokes the cab and pumps up the heat. 2X intakes provides greater airflow, greater cooling and less stress on the fan while maintaining negative pressure. Some here go as far as 3X and 4X.