Chef., My hundred plus engine driven holding plate system designs all using the SD 508 compressor have provided knowledge of what works and what does not. If your system is not in balance, performance will be poor and compressor’s service life will be at risk. It is true that compressor’s temperature will be too hot to touch during the first few minutes on first pull down of warm plates. If condenser’s size and its cooling medium are adequate high pressure at compressor will not exceed 135 psi using 134a refrigerant. As plate liquid drops one degree per Btu pound and reaches freeze point ice starts to form on coils lowering load on compressor. When holding plate’s evaporator coils reach a temperature 20 degrees below solution’s eutectic point plate is frozen solid and high pressure may drop as low as 95 psi. The important thing to remember is a holding plate is not a conventional evaporator and it is never at a stable thermo dynamic state, as ice forms on coils first reducing heat transfer. Twenty five years ago it was believed that plates in series did not affect daily compressor run times today most of these systems have more than one TXV.

Something you should think about is would you select a 25 ton condensing unit for 4 one ton air handlers in series, this is what you are doing by running this engine driven compressor at 1800 rpm. Just because you might rate a holding plats heat absorption when frozen at 4000 btu does not mean it will except that rate of heat transfer during a short freezing cycle. The 25 ton will remind you of the design error by frequent cycling and tripping temperature restart overload, your out of balance design will not protect compressor.