being placed on the system such as loading a freezer or cooler the separate and distinct flow paths 126 a and 126 b allow each side of the cooling coil system 128 to be independently defrosted which in addition to providing efficient defrosting also enhances the building atmospheric dehumidification explained in greater detail below the cold fluid circulating through the cooler 124 receives heat from the contents of the cooler 124 such as food thereby cooling the cooler contents fluid is returned to the heat exchanger 112 through pump 130 a defrost system 150 is also connected to the cooler 124 to allow the cooling coils 128 to be defrosted the defrost system is a closed coil system containing a defrost fluid of the same composition as the cooling solution described above the defrost system overlaps with the cooling system 120 in the region of the cooler 124 specifically the cooling coils 128 include a shared flow path between valves a and b and c and d which allows the defrost fluid to be circulated through the cooling coils 128 preferably the defrost loop 150 is closed in order to prevent contamination of the cooling fluid the defrost system 150 includes a pump 152 for circulating the fluid within the.