Refrigerator unit defroster with auxiliary heater

Claim 1

IN A REFRIGERATION SYSTEM HAVING A COMPRESSOR UNIT, A CONDENSER, AND AN EVAPORATOR ARRANGED IN SERIAL RELATION AND A HOT GAS BY-PASS LINE NORMALLY COMMUNICATING THE DISCHARGE OF THE COMPRESSOR UNIT DIRECTLY WITH THE EVAPORATOR DURING A DEFROST CYCLE, THAT IMPROVEMENT COMPRISING AN AUXILIARY HEATIN UNIT ADAPTED TO BE CONNECTED SERIALLY INTO THE HOT GAS REFRIGERANT BY-PASS LINE, SAID HEATER UNIT INCLUDING A TANK HAVING A QUANTITY OF LIQUID THERIN, A CONTINUOUSLY OPERATIVE THERMOSTATICALLY CONTROLLE HEATING UNIT DISPOSED IN SID LIQUID FOR MAINTAINING THE LIQUID AT A PREDETERMINED ELEVATED TEMPERATURE, A HEAT EXCHANGE COIL DISPOSED IN THE TANK AND ADAPTED TO BE CONNECTED IN SERIES WITH THE BY-PASS LINE FOR PASSAGE OF HOT GAS REFRIGERANT THROUGH THE COIL WHEREBY THE LIQUID ENCLOSING THE COIL WILL HEAT THE HOT GAS REFRIGERANT TO A PREDETERMINED TEMPERATURE, THE VOLUME OF SAID LIQUID IN THE TANK BEING CONSIDERABLY GREATER THAN THE VOLUME OF THE COIL DISPOSED IN THE TANK, SAID HEAT EXCHANGE COIL BEING IN THE FORM OF A SPIRAL COIL HAVING DOUBLE CONVOLUTION SPACED LONGITUDINALLY AND EXTENDING FROM TE INLET TO THE OUTLET SIDE OF THE COIL, SAID INLET AND OUTLET SIDES OF SAID COIL BEING DISPOSED AT THE SAME END OF SAID COIL.