Muddy if ur useing a split why dont u supp wit co2 and seal ur room. I got my room as seald as could be given it does pull a little air from the outside from the ac blowin.the hot air out but i dont even run a exhaust fan. Just supp with co2 and i have no problems. I know alot of ppl r against the seald room but i wouldnt do it any other way i cant see wasting my rooms ecelctical energy and co2 from just blowimg it out the room to let new air in. N yeah i know my portable ac is still wasting some of my co2 thats why im so interested in getting a split but im real curios about those water chillers for the outdoor building im plannin to build later ive never really heard any one compare with real world exp on them that wasnt trien to sell me one. Im curios to how efficent they really r versus air cooling to tue outside of a room with an ac.