How are external and internal ice-on-coil systems distinguished?
a) By the thickness of the ice that can be formed on the outside of the coils
b) By which fluid carries away the cooling effect: glycol flowing over the outside of the coils or water inside the coils
c) By the thickness of the ice that can be formed on the inside of the coils
d) By the discharge temperature
e) By which fluid carries away the cooling effect: water flowing over the outside of the coils or glycol inside the coils