Split air evaporator rear air circulation ducts

The rear air return, however, depending on the need, the lower air return option can be used (dashed lines). The ducts may have a rectangular or circular section. For evaporators with a capacity greater than or equal to 24,000 Btu / h, a minimum of 3 ducts of circular section must be installed for air distribution. For evaporators with a capacity greater than or equal to 36,000 Btu / h, 4 tubes of circular section must be installed.