Abstract: A hot water circuit (50) supplies water to a plurality of rooms (20) in a building from a central water source (22). Each room (20) has dispenser (24) and an air conditioner (28) and a liquid heat exchanger (38). The air conditioner (28) includes a condenser (30) that abuts the liquid heat exchanger (38) for warming the water from the central water source (22). When too much water is heated, some returns to the central water source (22). Some water is cooled by a dissipating heat exchanger (76, 74) disposed on a heated water return line (70). The return line (70) is connected to the central water source (22). An auxiliary system (84) runs through the dissipating heat exchanger (76, 74) to cool the water in the return line (70).