I have a newly constructed home - single floor on a slab with an attached double car garage at one end and an attic that runs the full length and width of the house. The home was built with 6 attic vents in the roof just below the very top of the roof line. They are circular and I'm guessing about 12" or 14" in diameter. I want to have a fan/s installed in the attic to pull more of the heat out. At the same time, I'd like to get some of the heat out of the garage which has no window. I'm considering installing a ceiling fan in the garage to pull the heat into the attic and one or two automatic fans in the attic. Would it be better to install the fan/s in place of one or two of the existing roof vents or should I install one larger fan in one end of the house with an vent in the opposite end? I was leaning toward replacing a couple of the roof vents since there are already openings through the house rather than creating new openings in the sides. Your advice is appreciated.

If you put a large ceiling fan in the garage, it should keep enough air moving in the garage to make it comfortable to work in. Blasting all that air into the attic would force the air in the attic out the existing vents. Wiring would be short and easy if the breaker box is in the garage.

I have a newly constructed home - single floor on a slab with an attached double car garage at one end and an attic that runs the full length and width of the house. The home was built with 6 attic vents in the roof just below the very top of the roof line. They are circular and I'm guessing about 12" or 14" in diameter. I want to have a fan/s installed in the attic to pull more of the heat out. At the same time, I'd like to get some of the heat out of the garage which has no window. I'm considering installing a ceiling fan in the garage to pull the heat into the attic and one or two automatic fans in the attic. Would it be better to install the fan/s in place of one or two of the existing roof vents or should I install one larger fan in one end of the house with an vent in the opposite end? I was leaning toward replacing a couple of the roof vents since there are already openings through the house rather than creating new openings in the sides. Your advice is appreciated.
... have any soffit, eave or gable vents? Is the ceiling finished or are there only ceiling joists exposed? Could it be the circular vents would accommodate roof turbines? When we replaced our shingles we installed turbines and then went about installing eave vents at evenly spaced intervals. This doesn't require any fan(s) and does a good job of keeping the garage cool until the washer/dryer are being used.

Thanks guys. It didn't occur to me that the air from the garage ceiling fan would force the hot air out of the attic. Makes sense. Kill two birds with one stone. That's the way I'm going and I suspect it will work. Appreciate your help.