Abstract: Fast defrosting and fast recooling of the evaporator coil is a refrigeration system, whether of the compression type or of the non-compression type operating as a thermal siphon system, is obtained by periodically terminating the flow of cooled liquid refrigerant to the evaporator unit and circulating only the fluid in the evaporator unit through a thermal storage reheat unit which is maintained in heated condition during operation of the system for defrosting the evaporator unit. The cold refrigerant normally supplied to the evaporator unit is stored during the defrost cycle for instant supply to the evaporator unit for recooling it at the termination of the defrosting cycle.