Special Control SiEBE18-52664 Function3.3 Defrosting OperationThe defrost operation is performed to solve frost on the outdoor unit heat exchanger whenheating, and the heating capacity is recovered.[Conditions to start]The defrost operation is started referring following conditions. Outdoor heat exchanger heat transfer co-efficiency Temperature of heat-exchange (Tb) Low pressure equivalent saturation temperature (Te) Timer (2 hours at the minimum)In addition, outdoor heat-exchange co-efficiency is derived from Tc, Te, and the compressorload.* From the preparing operation to the defrost operation, and from the defrost operation to theoperation after defrost, the compressor stops for 110 sec. to reduce noise on changing of thefour way valve.Outdoor unit actuator Defrost preparationoperation Defrost operation Post Defrost operationCompressor Upper limit control 140 Hz2-step increase from52 Hz to(Pc - Pe>0.4 MPa)every 20 sec.Outdoor unit fan STEP8 OFF STEP8Four way valve ON OFF ONMain electronic expansion valve(EV1) SH control 2000 pls 200~400 plsSubcooling electronic expansionvalve (EV2) 0 pls 0 pls 0 plsHot gas bypass valve (SVP) OFF ON ONReceiver gas discharging valve(SVG) ON → OFF ON → OFF ON → OFFEnding conditions 130 sec. • Max. 18 min.• Tb >11°C • 160 sec.• Pc - Pe>0.4MPaor orIndoor actuator During defrostIndoor unit fanThermostat ON unit OFFStopping unit OFFThermostat OFF unit OFFBP unit electronic expansionvalveThermostat ON unit SH controlStopping unit 80 plsThermostat OFF unit SH control
