Ventilation Help Please

So I recently ran into technical difficulties and had to change locations and while I like my new area I ran into an issue, there is only one ventilation opening in the room 6" or 8" and no way to make a second. Previously I didn't have to worry about it but now I have an air cooled hood and larger light but if I just run my vents out and open the room for fresh air would the vaccum it would create not cause problems? I considered having the vent out and an inlet both run through the same vent but that would greatly restrict the flow at the ends and it would probably cycle the hot air right back into my room, basically my fan and exit ducting pulling out while a second peice would naturally pull in by the vacuum of the other.

I don't know how much sense that can make without any pics but any input or help would be greatly appreciated.

i only have 1 outlet and the vacuum is not a problem. i have it as sucking air from the light and out of a hole in the wall and air gets sucked in through the bottom of the door. as i said its given me no problems with restrictions on air flow or temps. the only problem is it sometimes sucks crap from the floor into my grow cupboard lol.

hope that helps

Yeah appreciate the reply, what size is your cabinet and lights?

ive got a 400w hps in a under stairs cupboard its real small, about 1.5 -2 meters height (at the top as its slanted) 1.2 meters wide.

i only have the fan on when the lights are on as the temps are fine.If you do it this way and put a carbon filter on it before the light due to the vacuum no smelly air should escape! so so clean air in and carbon cleaned air out.

this is the fan im using RUCK Fan 125mm/5 Inch Low Power Version

I was going to run mine from one side of my hood then ducting, then fan, behind the fan the filter then ducting out. I took the glass out my hood and didn't want the filter before my hood because wouldn't it be pulling unfiltered air from under the light?

I'm using a 400cfm inline and a phat filter

depends on what type of filter you have really. im not running one at the mo but all the ones ive seen wouldnt work like that because they suck air through the filter... (struggling to find words to describe what i mean). all the filters ive seen have only 1 input for ducting so if you did it like i think your saying it will lose suction from the light as it will be sucking air from the filter if you know what i mean???

dont know if this pic helps describe what im on about? unless you have a different type of filter to this?

i do what your saying and have my filter outside the room so the air is being sucked out my light and room, through ducting with the carbon filter on the end, ( so im blowing through the filter not sucking.

ah I know what you mean I though they were a tube/funnel style but they Pull from all around I'll probably get a slightly higher cfm fan and just push through the filter. Lol blame the bud for not noticing that sooner