A water cooled condensing unit (the outside part of a split A/C system) would work fine, but it will use lots of water. An air cooled condensing unit will use a fan to remove the heat it removes from the grow room. The effects of the heat removal can be minimized by blowing the hot air into thick undergrowth or bushes. There is no way to use a water cooled device and not use a lot of water. Hope this helps.