People that havent been trained simply dont understand Air and Cooling so I am going to attempt to help out. First some things I see commonly done wrong by growers. A window unit goes into a window. It is not designed to be ducted with cardboard or vented into a garage. These things work marginally at high temps and without proper air flow all they do is use energy. I was at a grow this weekend thats improperly vented and the power bill is 600 where it should be 300. Thats 3600 a year wasted that could go to making it work properly there fore saving money every year. That will pay for a mini split that uses ½ the electricity as a window unit. Think Green in your grow room! Moving Air is a lot cheaper than chilling it so if your hoods are hot then your venting system sucks. You should be able to hold your hands on your hoods and glass and not have to move them. If they are generating heat then your now paying to Chill the room and that cost a lot more. A 1200 CFM vortex uses like 1 amp a 10,000 btu ac uses like 8 Air is a Fluid! Think of it as water. Everyone go look at there venting flex if water was running through it would it cavitate and restrict and all those bends without elbos? So does air you just cant see it. Air has friction and just like any fluid just less but its still a huge factor in venting. Lets look at the proper way to vent a closed system. Lets explore WE want to install a hard pipe system as our main trunk line this will prevent friction flex is used only as short connecting tubes. Ok I cut a 8" Dryer Vent in and tore off the flapper and cover. We then attach a 8" elbo and a 7 foot section of pipe to go from down low to up high. At the top of the cieling below the plate we come through with the 8" duct using an elbo 8" As this duct passes through MzJill's hydro room we chop in a 4" hole to provide fresh air for her hood. Being close to the intake it will get lots of good clean fresh air and stay cool even with the smaller duct.