Manitowoc QM30 Series Installation, Operation And Maintenance Manual

Also see for QM30 Series: Technician's handbook Technician's handbook Technician's handbook Installation and use manual Installation and use guide

Contents

Manitowoc QM30 Series Installation, Operation And Maintenance Manual Manual pdf 8 page image

8 Part Number 00000xxxx 05/10Section 3OperationSequence of Operation*Initial Start-Up or Start-Up After Automatic Shut-OffINITIAL START-UP OR START-UP AFTER AUTOMATIC SHUT-OFF1. Water PurgeThe water fill valve and the hot gas valve are energizedfor 2.9 minutes (175 seconds). This ensures that the icemaking cycle starts with fresh water, and that therefrigerant pressures are equalized prior to refrigerationsystem start-up.2. Refrigeration System Start-UpThe compressor starts 2.9 minutes (175 seconds) afterthe water fill valve and hot gas valve are energized. (Thewater fill valve and hot gas valve remain energized for 5seconds during compressor start-up, and then shut off.)The compressor remains on throughout the entire freezeand harvest cycles.3. Freeze CycleThe condenser fan motor and water pump are energizedand remain on throughout the entire freeze cycle. Aneven flow of water is directed across the evaporator andinto each cube cell, where it freezes.The control system automatically determines the lengthof the freeze cycle by monitoring the temperature of therefrigeration system liquid line.4. Harvest CycleThe condenser fan motor and water pump de-energize.The water fill valve energizes to purge the water in thewater trough. The hot gas valve also energizes at thebeginning of the harvest cycle to divert hot refrigerantgas into the evaporator. The hot refrigerant gas warmsthe evaporator, causing the cubes to slide, as a sheet,off the evaporator and into the ice storage bin.The control system automatically determines the lengthof the harvest cycle, based on the temperature of therefrigeration system liquid line at the end of the freezecycle. At the end of the harvest cycle, the ice machinereturns to another freeze cycle.5. Automatic Shut-offThe ice machine shut-off is controlled by the level of icein the ice storage bin. When the bin is full, ice cubescontact the bin thermostat bulb holder, which cools downand opens to stop the ice machine. The ice machineremains off until enough ice has been removed from thebin. This causes the thermostat bulb holder to warm andclose, restarting the ice machine. When the ice machinerestarts, it returns to the start-up sequence.Ice Making Sequenceof OperationControl Board Relays1Compressor2Hot Gas ValveWater Fill Valve3Water PumpFan MotorLength of“ON” TimeStart-Up*1. Water Purge OFF ON ON 2.9 Minutes(175 Seconds)2. RefrigerationSystem Start-Up ON ON OFF 5 Seconds3. Freeze Cycle ON OFF ON Automaticallydetermined4. Harvest Cycle ON ON OFF Automaticallydetermined5. Auto Shut-Off OFF OFF OFF Until bin thermostatre-closes