in order for an a/c unit to work it has to recirculate the air of the grow room or house and eventually it cools down the room or house but it takes awhile if you ventilate either one much at all neither a/c will be able to do its job and all that co2 you just put in your room will go out the window.
your first drawing would work the best and if you disconnect it from your central a/c and use a larger blower it should be fine, if you do not unhook it from your central a/c your grow room will probably be the only cool room in the house.
apparently you have a window wich is a great spot for the intake or exhuast of the lights so now you just need one other intake or exhuast short of cutting a hole in the side of the house which may be your only option in some cases, but usually you can use the attic and exhuast the lights to the attic may require an 8 inch hole or if its not a basement house you can also disconnect your a/c heat ducting going to the room and block it off and use that hole for an intake to pull air from under the house.
bejay Reviewed by bejay on . help grower seeking advice i´m trying to decide if a 10000 btu air conditioner will bring down the temperatures in the room or try something bigger. The room space is 8x12x7 with 3 600w HPS lamps with cooltube, 8 plants under each lamp. Th strain is NLxBigBud. Thanks in thanks in advance for your help. Rating: 5