higher pressure acting on an opposite side of the check valve 78 prevents refrigerant from entering the manifold 54 from the manifold 52 the advantages similar to the benefits of the fig1 a embodiment are obtained here as well in the evaporator operation depicted in fig2 b the refrigerant flows from the refrigerant line 56 into the refrigerant line 64 through the check valve 76 and expansion device 80 while the check valve 74 prevents the refrigerant to enter the refrigerant line 62 and to bypass the expansion device 80 in the expansion device 80 that can be of a fixed orifice type e g a capillary tube an accurator or an orifice or a valve type e g thermostatic expansion valve or electronic expansion valve the refrigerant is expanded to a lower pressure and temperature and enters the manifolds 52 and 54 in a parallel manner since the check valve 78 doesn 39 t prevent refrigerant from entering the manifold 54 now form the manifolds 52 and 54 the refrigerant simultaneously flows through all heat exchange tubes 22 in a single pass arrangement enters manifold 60 and leaves the parallel flow evaporator 90 through the check valve 72 and refrigerant lines 66 and 58 to be delivered to the four way reversing valve and returned to the compressor the check valve 70 installed in the refrigerant line 82 prevents the refrigerant from immediately leaving the manifold 54 and parallel flow heat exchanger 90.