WHAT IS SUBCOOLING

SUBCOOLING IS AN IMPORTANT PIECE OF INFORMATION TO HAVE REGARDLESS OF WHAT METERING DEVICE WE ARE USING AT THE EVAPORATOR. WE TYPICALLY CHARGE A SYSTEM BY SUBCOOLING METHOD WHEN WE ARE ON AN EXPANSION VALVE SYSTEM (TXV). A SPECIFIED SUBCOOLING NUMBER WILL BE PROVIDED BY THE MANUFACTURE.

SUBCOOLING IS A READING WE TAKE TO VERIFY HOW MUCH HEAT IS BEING REMOVED FROM THE REFRIGERANT AT THE CONDENSER COIL. TOO MUCH REMOVED CAN BE BAD AS WELL AS TOO LITTLE REMOVED. IT NEEDS TO BE ACCURATE SO WE CAN BE SURE THAT OUR LIQUID LINE (HIGH SIDE) IS COMPLETELY FILLED WITH REFRIGERANT. THAT WAY THE METERING DEVICE CAN WORK PROPERLY. AN IDEAL SUBCOOLING RANGE WILL GENERALLY BE BETWEEN 5-15*F. BUT ALWAYS REFER TO MANUFACTURE RECOMMENDATIONS.

TOO OBTAIN THIS READING WE NEED TO TAKE A PHYSICAL LINE TEMPERATURE OF THE LIQUID LINE NEAR THE SERVICE VALVE, AND LETS SAY WE GET A READING OF 90*F. WE THEN NEED TO CONVERT OUR LIQUID LINE PRESSURE (ON OUR GAUGES) TO TEMPERATURE. FOR EXAMPLE, IF WE ARE ON AN R410A SYSTEM AND OUR HIGH SIDE PRESSURE IS APPROXIMATELY 318PSI, WE WILL THEN REFER TO OUR PT CHART AND SEE THAT R410A AT 318PSI IS ABOUT 100*F. BECAUSE WE ARE SUB-COOLING (REMOVING HEAT AT THE CONDENSER) OUR PHYSICAL LINE TEMPERATURE SHOULD BE COOLER THAN OUR PRESSURE/CONVERTED TEMPERATURE.

100*F – 90*F = 10*F OF SUBCOOLING.

                                                                                            CARLOS S.