Carrier 42XQ Series Installation And Start-up Instructions Manual

Also see for 42XQ Series: Owner's manual Owner's manual

12Since the interconnection pipes are created on site, it is essential to clean andevacuate the pipes and the indoor and outdoor units.NOTECleaning must be performed by circulatingnitrogen through the pipes of the system.Cleanliness is extremely important becauseit prevents dirt resulting from the installationfrom getting inside the pipes and causingproblems later.The access points are the servicevalves on the outdoor unit.The valves leave the factory in the closed positionto keep the refrigerant in the outdoor unit.To perform the evacuation, keep the valve inthe closed position and connect the manifoldhose to the valve and the other end to thevacuum pump.It is recommended to proceed with theevacuation of the two connections of theservice valves simultaneously.The range to be reached must be locatedbetween 250 and 500 microns.ATTENTION !!!Never load liquid into the suction servicevalve. When you want to do this, use aservice valve for the expansion pipe.IMPORTANT !!!5.3 Adjusting the Gas LoadTo adjust the refrigerant load in the machines, superheat can also be used as aperimeter. (Consider a range of 5 to 7 o C)SUPERHEAT1.Definition:Difference between the suctiontemperature (Ts) and the saturatedevaporation temperature (Tes).SA = Ts - Tes2.Measuring equipment required:• Manifold.• Bulb thermometer or electronic thermometer(with temperature sensor).• Insulation tape or foam.• Pressure - Temperature conversiontable for R-22.3.Measuring steps:1o - Bring the bulb or sensor of the thermometerinto contact with the suction pipe 15cmfrom the intake of the condenser. Thesurface must be clean and the measurementis performed on the upper part of thepipe to prevent incorrect readings.Cover the bulb or sensor with foam toinsulate it from the ambient temperature.2 o - Install the manifold on the suctionpipe (low pressure gauge).3 o - Once the operating conditions havebecome stabilized, read the gaugepressure of the suction pipe. Obtainthe saturated evaporator temperature(Tes) by consulting the R-22 table.NOTE4 o - Read the suction temperature (Ts)shown on the thermometer. Take severalreadings and calculate their average,which will be the adopted temperature.5 o - Subtract the saturated evaporationtemperature (Tes) from the suctiontemperature. The difference representsthe superheat.6 o - If the superheat is between 5 & 7 o C, therefrigerant load is correct. If it is below thisrange, too much refrigerant is being injectedinto the evaporator, and it is necessaryto remove refrigerant from the system.If the superheat is high, too little refrigerantis being injected into the evaporator, andit is necessary to increase the refrigerantin the system.4.Calculation example:- Suction pipe pressure (pressure gauge)..75 psig- Saturated evaporation temperature (table)..7oC- Suction pipe temperature (thermometer)..13oC- Superheat (subtraction)..........................6 o C- Superheat OK - correct loadBefore starting to operate the equipment,after adding the additional refrigerant load (ifnecessary), open the service valves on theoutdoor unit.ATTENTION !!!Do not forget to purge the air from thehose.• After creating the vacuum, addpositive pressure with R-22 so thatthe vacuum is broken.To proceed with loading the refrigerant, simplykeep the service valve in the factory position(closed) and connect the manifold hose tothe valve (Schrader valve) of the service valve.