Air conditioning control apparatus

Claim 1

A CONTROL ARRANGEMENT FOR AN AIR CONDITIONING APPARATUS OF THE TYPE HAVING A HEAT EXCHANGE UNIT ADAPTED TO COOL AND DEHUMIDIFY AIR FROM AN ENCLOSURE COMPRISING A THERMOSTAT MOUNTED FOR EXPOSURE TO AIR OF SAID ENCLOSURE, A TEMPERATURE RESPONSIVE MEMBER IN SAID THERMOSTAT MOVABLE IN ONE DIRECTION AS THE TEMPERATURE OF THE AIR ADJACENT SAID MEMBER INCREASES AND MOVABLE IN A REVERSE DIRECTION AS THE TEMPERATURE OF AIR ADJACENT SAID MEMBER DECREASES, SWITCH MEANS OPERATED BY SAID TEMPERATURE RESPONSIVE MEMBER TO ENERGIZE SAID AIR CONDITIONING APPARATUS AS THE AIR TEMPERATURE ADJACENT SAID MEMBER RISES ABOVE A PREDETERMINED HIGH TEMPERATURE AND FOR DE-ENERGIZING SAID AIR CONDITIONING APPARATUS AS THE TEMPERATURE ADJACENT SAID MEMBER FALLS BELOW A PREDETERMINED LOW TEMPERATURE, A BIASING HEATER IN SAID THERMOSTAT FOR ADDING SMALL QUANTITIES OF HEAT TO THE AIR SURROUNDING SAID TEMPERATURE RESPONSIVE MEMBER THEREBY BIASING SAID MEMBER IN A DIRECTION TENDING TO CLOSE SAID SWITCH MEANS TO ENERGIZE SAID AIR CONDITIONING APPARATUS, A THERMISTOR HAVING A COEFFICIENT OF RESISTANCE INVERSELY RELATED TO THE TEMPERATURE OF SAID THERMISTOR AND DISPOSED OUTSIDE SAID ENCLOSURE SO THAT THE RESISTANCE OF SAID THERMISTOR IS RESPONSIVE TO THE TEMPERATURE OF THE OUTDOOR AIR, SAID THERMISTOR BEING ELECTRICALLY CONNECTED IN SERIES WITH SAID BIASING HEATER THEREBY TO DECREASE THE CURRENT FLOW THROUGH SAID HEATER AND THE QUANTITY OF HEAT OUTPUT THEREOF AS THE OUTDOOR AIR TEMPERATURE FALLS AND ADAPTED TO INCREASE THE CURRENT FLOW THROUGH SAID HEATER AND THE HEAT OUTPUT THEREOF AS THE OUTDOOR AIR TEMPERATURE RISES, A BYPASS CIRCUIT AROUND SAID THERMISTOR FOR SHUNTING ELECTRICAL CURRENT AROUND SAID THERMISTOR TO SAID BIASING HEATER, HUMISTAT CONTROL MEANS IN SAID BYPASS CIRCUIT FOR INCREASING THE CURRENT FLOW THROUGH SAID BYPASS CIRCUIT IN RESPONSE TO HIGH HUMIDITY CONDITIONS WITHIN SAID ENCLOSURE AND FOR DECREASING CURRENT FLOW THROUGH SAID SHUNT CIRCUIT IN RESPONSE TO LOW HUMIDITY CONDITIONS WITHIN SAID ENCLOSURE THEREBY TO ASSURE INCREASED HEAT OUTPUT FROM SAID BIASING HEATER IN SAID THERMOSTAT WHEN HIGH HUMIDITY CONDITIONS EXIST IN SAID ENCLOSURE EVEN THOUGH THE OUTDOOR AIR TEMPERATURE MAY BE RELATIVELY LOW.