Four pipe induction system for air conditioning - has single closed expansion tank for hot and cold circuits

摘要

Counter flow heat exchangers provide hot and cold water to the main distribution systems from which pairs of branch pipes serve individual room induction units. Each unit is controlled by valves operated sequentially by a room thermostat. The single expansion tank is of the pressurised closed type and is placed in the interconnecting pipe linking the hot and cold water systems. The hot connection is at the top of the tank and the cold at the bottom. Inside the tank are several closed bellows containing gas under pressure which enable changes in water volume to be taken up. The tank is fixed vertically to allow a temperature gradient to exist between the hot and cold sides.