Air-cooled condensers are used universally on smaller refrigerating units, but seldom for capacities in excess of 3 tons of refrigeration. They are equipped for natural draft and fan cooling and are termed according to their construction as plain tubes, finned tubes, plate type, and series or parallel pass. The conventional air-cooled condenser consists of an extended-surface coil across which air is blown by a fan. In operation, hot discharge gas enters the coil at the top. As it is condensed, it flows to a receiver located below the condenser. Figure 8-1 and Figure 8-2 show typical air-cooled condensing units.
Air-cooled condensers should always be located in a well ventilated space. This is how the heated air may escape and be replaced by cooled air. Because of space requirements, air-cooled condensers are normally constructed with a relatively small face with several rows of tubing in depth. As the air is forced through the condenser, it absorbs heat, and the air temperature rises. Therefore, the efficiency of each succeeding row in the coil decreases, although coils up to eight rows in depth are frequently used.