Ventilation advice

[Lard Bernard]

box: 6x5x4
garage attic space: about 300-400 sq feet.

i am trying to come up with ways to keep the attic temp down and box cool here is what we are doing... read my journal for more info.

insulating the rafters and walls of the space and probably sheetrocking it. the garage below stays decently cool in the summer so we were planning on running a vent line from down there through the air cooled hood of the 600w light and out of the space completely. as for the box itself i was debating on whether or not to run a Tee off of the line going to the light and have a small inline duct fan blowing some of that out into the attic. then just intake the air from the attic into the box or run a tee into the box.

here is an idea of what we are going to do. let me know if you think it will work.

 

[Lard Bernard]

probably going to need some back draft dampers but not really sure where.

 

[Hogdady]

not quite sure from the pic....are exhausting the light into the attic space or to the outside?

 

[Lard Bernard]

exhaust is going outside.

 

[Hogdady]

looks like you will need a backdraft damper at the outlet of the light exhaust to prevent the air from the filter from going back into the light when that fan is off....

 

[Lard Bernard]

what i am worried about is... if we get the attic air tight the 200 cfm that is pulling the air out of the box needs to have the same or more supplied to the space.

so i guess i am answering my own question here... i need to get a fan greater than or equal to the 4" 200 cfm fan i have pulling out of the box and out of the attic. so the attic stays balanced and there is no stale air.

also i was wondering if there would be any reason not to try and save some money by rigging the honeywell to use in the ducting system. i could try to make it air tight and that could be what i can use to pull air out of the garage and into the attic. the thing to keep in mind is i have to use residential trim hvac vents in whatever i am doing so it is inconspicuous from the garage.