SiUS04-702 Control Specification (15/18/24 Class)Function and Control 554.10 Low Hz High Pressure LimitOutline Heat Pump OnlySet the upper limit of high pressure in a low Hz zone. Set the upper limit of the indoor heatexchanger temperature by its operating frequency of Hz. Separate into three zones, reset zone,unchanged zone and drooping zone and the frequency control must be carried out in such zones.Detail Separate into ZonesNote: Drooping: The system stops 2 minutes after staying in the drooping zone.4.11 Defrost ControlOutline Heat Pump OnlyDefrosting is carried out by the cooling cycle (reverse cycle). The defrosting time or outdoor heatexchanger temperature must be more than its fixed value when finishing.Detail Conditions for Starting DefrostThe starting conditions must be made with the outdoor air temperature and heat exchangertemperature. Under the conditions that the system is in heating operation, 6 minutes after thecompressor is started and more than 44 minutes of accumulated time pass since the start of theoperation or ending the defrosting.Conditions for Canceling DefrostThe judgment must be made with heat exchanger temperature. (39°F~54°F)FrequencyCompressorFour way valveFanElectronic expansionvalve openingONOFFONOFFONOFF0Hz5sec.450pps450pps450pps Initial openingPI control5sec.45sec.60sec. 460 sec.120sec.(R4082)
