Sounds kind of what I have setup for the winter months. I don't water cool, but I do pump colder air from under my floor through a hole in the floor and a dryer hose. Sounds like he is doing the same thing but with the radiator mounted to the underside of the floor(roof of the basement), or just running the tubing through holes in the floor and down to the basement. Even in the summer, the air is much cooler than what is inside the house usually. It stays quite cool under my house.