We caught sight of a gigantic machine I immediately recognized, dangling from a huge crane, as we drove by this morning, even though it was about a block away. This is the "chiller", the heart of the system which provides the air conditioning for very large buildings, like Sears stores. We parked and walked on around the building seen in the background of the 2nd. and 3rd. pics, a 26 story tower of rooms, and spotted the machine we had seen already sitting on a flat-bed, ready to be hauled away. It was an old machine, likely originally installed when the building was put up, about 30 years ago. It probably had a motor burn-out, or bearing failure, and age dictated it be scrapped. These things are very large and heavy, likely 10 tons or so, and very expensive. Replacing one requires a special breed of worker, highly skilled, a Millwright who places and secures the machine, Welders and Electricians of the highest caliber to hook it up. Below is the old unit. Below, the new replacement being eased in through a dock-door. It's size may be judged by the workers around it. Supported as it is, by slings, they can only enter so far, until the forward sling reaches the upper part of the doorway. Then it will be lowered onto special rollers, to be pulled into the building, probably by a fork-lift truck. Note in the top pic, two large (about 8-inch diameter pipes) marked by a white paint band and arrow on the closest part of the machine, have been cut from the original installation by "burning" them through using a cutting-torch. Rough way to do it, but time is of the essence. Below, taken about 20 minutes after the above pic, they have it almost entirely into the building, now sitting on rollers. By the time we finished our walk, about an hour later, the old machine, and the crane, were already gone! I would venture to say that very few people have ever seen an HVAC (High Volume Air Conditioning) Chiller, but have very often felt it's efforts put forth, as they walked malls in the summertime, or visited large stores and the like, enjoying the nice cool air! Chillers are huge and expensive, but rather simple in concept. Usually, they have two water-filled tanks, each having heat-exchange piping within. The drive motor spins a large turbine-like fan enclosed in a snail-shell-like case, compressing Freon gas until it liquefies, after which it is sprayed as it evaporates, making it very cold, and passed through one heat exchanger, cooling it's surrounding water, which is then passed through the other heat exchanger in the other tank, cooling that tank's water, which is being circulated through piping to a large, or several in some cases, "cooling tower" outdoors, where the water is deprived of it's heat (which was removed from the building) by evaporating some of the water into the air. Everything must be maintained leak-tight. The Freon gas used, in past practice Freon No. 12, liquefies quite easily, much more so than that used in refrigerators or auto A/C. So, there are 3 distinct and separate "circuits" in operation: the Freon circulating around and around, the water it cools circulating to radiators in the building where giant fans move the cooled air throughout the building, and the water circuit flowing outside to the cooling tower(s). "Big Business" necessitates "Big Money" invested. Frank