Plate heat exchangers (PHEs) have been installed in larger heat pump systems and refrigeration systems since the 1980s. Tech-nicians who deal with these systems need to know some specific details of how they work.Part one of this article covered PHE design, on-site assembly and service, leak indication, freezing risk, and resistance from vibration, pressure, and seismic occurrences. This week the article continues its discussions of the plate heat exchanger as vaporizer and condenser.