400w ventilation question

Hi all,

My set-up is a 400w air-cooled HID (vegging with MH right now) in closet that has a central heating duct going through it. So far, I've been sucking air through with the hood with a home depot style duct booster fan with the "house" duct blowing in fresh air. It's been working great so far and temps stay between 75 and 80 degrees, humidity at 40-50% and the lights about 8-10" from the tops.
I want to switch to a more powerful fan (vortex or can-fan 6", roughly 450 cfm) soon so that I don't have run the central fan all the time but still maintain airflow and cool temperatures.

Can anyone give me input on this? My plan is as follows (I'm not sure how to make a diagram, I hope this makes sense)

Air in:
central heating inlet - split = one inlet for the hood + one for the room

Air out:

exhaust out of grow room-450cfm inline fan sucking in air - split = exhaust from hood + exhaust for room with carbon filter

Is this the best way to go about it or is there a simpler way to keep the air flowing?

Any input is appreciated!

Thanks!

Nobody?

Ok, so here's the revised plan:

Intake:

A/C duct blowing in -> plant area

(i can also add the booster fan here if necessary)

Exhaust:

exhaust to room < -6" fan <- hood <- carbon filter

the room is maybe 150 cubic feet. What kind of filter would I need to grow some stanky plants in this kind of set-up? Also, do you think I would need some kind of speed controller or thermostat for the fan (or fans) or should I just keep them running when ever the lights are on? Is there such a thing as 'too much' airflow?

Does anyone have any experience hooking up their venting system to existing dryer or heating ducting?

I want to get this set up before switching to 12/12. Any advice is appreciated!

why not blow the intake through the ducting to cool and expel heat, and hook the inline fan up after the light, and push air out into the carbon filter outside

Thanks, but that won't work because I'm using an existing exhaust grille and I can't blow out of the filter.

I went ahead and hooked it up the first way with the splits and it's working well so far. The whole thing is noisy as hell, so I'm gonna need to find some sort of speed controller for the fan...

Any suggestions. Are the temperature controlled ones worth it?