I used a chevy blazer radiator and cold water from the spring that feeds my house water supply to cool my home in hot weather. Water is pumped up from the cistern to the radiator/fan in the upstairs bedroom. Cold water at 52 degrees enters the radiator and it leaves at 68 degrees. It maintains the room at 70 degrees during the heat wave. It is removing btu's equal to 9 horsepower.