Refrigerant Circuit SiUS181631EA42 Refrigerant Circuit1. Refrigerant Circuit1.1 Outdoor UnitNo. indiagram Symbol Name Major FunctionA M1C Compressor motor The compressor is operated on frequencies between 36 Hz and 195 Hz by using theinverter. (31 steps)D M1FM2F Fan motor Since the system is of air heat exchanging type, the fan is operated at 8-step rotationspeed by using the inverter.E Y1E Electronic expansion valve(Main) While in heating operation, PI control is applied to keep the outlet superheated degree ofthe air heat exchanger constant.F Y3E Electronic expansion valve(Subcooling) PI control is applied to keep the outlet superheated degree of the subcooling heatexchanger constant.G Y2S Solenoid valve(Hot gas bypass) Used to prevent the low pressure from temporary falling.H Y3S Solenoid valve (Unload circuit) Used for the unloading operation of the compressor.M Y1S Four way valve Used to switch the operation mode between cooling and heating.N S1NPH High pressure sensor Used to detect high pressure.O S1NPL Low pressure sensor Used to detect low pressure.P S1PH High pressure switch In order to prevent the increase of high pressure when an error occurs, this switch is activatedat high pressure of 4.0 MPa (1338 ftAq) or more to stop the compressor operation.S — Fusible plug In order to prevent the increase of pressure when abnormal heating is caused by fire, etc., the fusible partof the plug melts at a temperature of 70 ~ 75°C (158 ~ 167°F) to release the pressure into the atmosphere.T — Pressure regulating valve(Receiver to discharge pipe)This valve opens at a pressure of 4.0 MPa (1338 ftAq) to prevent pressure increase, thus protectingfunctional parts from damage due to the increase of pressure in transportation or storage.1 R1T Thermistor(Outdoor temperature: Ta) Used to detect outdoor temperature, correct discharge pipe temperature, etc.2 R2T Thermistor(Discharge pipe: Tdi)Used to detect discharge pipe temperature, for temperature protection control of thecompressor, etc.3 R3T Thermistor(Suction pipe 1: Ts1) Used to detect suction pipe temperature, keep the suction superheated degree constant inheating operation, etc.4 R4T Thermistor(Outdoor heat exchanger: Tb)Used to detect liquid pipe temperature of the outdoor heat exchanger, determinedefrosting operation, etc.5 R5T Thermistor(Suction pipe 2: Ts2) Used to calculate the internal temperature of the compressor etc.6 R6T Thermistor (Subcooling heatexchanger gas pipe: Tsh) Used to control the subcooling electronic expansion valve.7 R7T Thermistor (Liquid pipe: Tl) Used to detect refrigerant overcharge in check operation, etc.Electronicexpansion valveDouble pipeheat exchangerElectronicexpansionvalveFusibleplugFilterHeat exchangerService portFour wayvalveHigh pressuresensorSolenoid valveSolenoidvalveLow pressuresensorService portCapillarytubeCapillarytubeCapillarytubeStop valve (with service port on field piping side φ7.9 mm (φ5/16 inch) flare connection)CompressorHigh pressureswitchPressureregulating valveFilterFilterFilterFilterOil separatorC : 3D052628S1NPLS1PHS1NPHAccumulator(F)(T)(E)(D) (D)(M)(N)(G)(P)(H)(O)(A)(S)(7)(6)(3)(2)(5)(4)(1)
