Manitowoc Q 1800 Installation And Use Manual

Also see for Q 1800: Use and care manual Manual Service manual Service technician's handbook Installation instructions

Contents

Ice Machine Operation Section 33-2Ice Making Sequence of OperationInitial Start-Up or Start-Up After AutomaticShut-Off1. Water PurgeBefore the compressor starts, the water pump andwater dump solenoid are energized for 45 seconds topurge the ice machine of old water. This ensures thatthe ice-making cycle starts with fresh water.The hot gas valve is also energized during the waterpurge, although it stays on for an additional 5seconds (50 second total on time) during the initialrefrigeration system start-up.2. Refrigeration System Start-UpThe compressor starts after the 45-second waterpurge, and remains on throughout the entire Freezeand Harvest Sequences. The hot gas valve remains onfor 5 seconds during initial compressor start-up andthen shuts off.The water fill valve is energized at the same time asthe compressor.At the same time the compressor starts, the condenserfan motor (air-cooled models) is supplied with powerthroughout the entire Freeze and Harvest Sequences.The fan motor is wired through a fan cycle pressurecontrol, therefore it may cycle on and off. (Thecompressor and condenser fan motor are wiredthrough the contactor. As a result, any time thecontactor coil is energized, the compressor and fanmotor are supplied with power.)FREEZE SEQUENCE3. PrechillThe compressor is on for 30 seconds prior to waterflow to prechill the evaporator. The water fill valveremains on until the water level probe is satisfied.4. FreezeThe water pump restarts after the 30-second prechill.An even flow of water is directed across theevaporator and into each cube cell, where it freezes.The water fill valve will cycle on, then off one moretime to refill the water trough.When sufficient ice has formed, the water flow (notthe ice) contacts the ice thickness probe. Afterapproximately 7 seconds of continual water contact,the harvest sequence is initiated. The ice machinecannot initiate a harvest sequence until a 6-minutefreeze lock has been surpassed.HARVEST SEQUENCE5. Water PurgeThe water pump continues to run, and the waterdump valve energizes for 45 seconds to purge thewater in the sump trough. The water fill valveenergizes for the last 15 seconds of the 45-secondwater purge.After the 45 second water purge, the water fill valve,water pump and dump valve de-energize. (Refer to“Water Purge Adjustment” on page 3-5 for details.)The hot gas valve also opens at the beginning of thewater purge to divert hot refrigerant gas into theevaporator.6. HarvestThe hot gas valve remains open and the refrigerantgas warms the evaporator causing the cubes to slide,as a sheet, off the evaporator and into the storage bin.The sliding sheet of cubes swings the water curtainout, opening the bin switch.The momentary opening and re-closing of the binswitch terminates the harvest sequence and returnsthe ice machine to the Freeze Sequence (steps 3 - 4).AUTOMATIC SHUT-OFF7. Automatic Shut-OffWhen the storage bin is full at the end of a harvestsequence, the sheet of cubes fails to clear the watercurtain and will hold it open. After the water curtainis held open for 7 seconds, the ice machine shuts off.The ice machine remains off for 3 minutes before itcan automatically restart.The ice machine remains off until enough ice hasbeen removed from the storage bin to allow the ice tofall clear of the water curtain. As the water curtainswings back to the operating position, the bin switchre-closes and the ice machine restarts (steps 1 - 2),provided the 3-minute delay period is complete.