Let's calculate quickly: a typical small room might require 5000 Btu/h to cool. One Btu is equal to a 1F temperature rise for 1 pound of water. Assume that "B

Let's calculate quickly: a typical small room might require 5000 Btu/h to cool. One Btu is equal to a 1F temperature rise for 1 pound of water. Assume that "Black Beauty" can get 20 degrees of thermal differential out of the water running through it (incoming: 50F, outgoing: 70F). That means we must pass 250 pounds, or just over 31 gallons, of water through the system each hour. That wouldn't be so bad if the water could be put to another use, like bathing, watering a vegetable garden or flushing toilets. But, 750 gallons of water a day is A LOT to use just for cooling -- consider that this is equivalent to four times the typical American household usage for a day. As with a lot of DIY geek hobbies, it's not so awful when one person does it, but it would be an environmental disaster if this was adopted by the general public. EDIT: Corrected my units.