VOGT ICE 12A4171M12, Service Manual

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MHG-LR Service Manual
HOW YOUR ICE MACHINE WORKS
1/6/2010
4-1
4. How Your Ice Machine Works
Principle Of Operation
For a detailed description of the functions of each control panel component, see Section 6. The
Mode Switch on each Module and the operator interface at the Master Panel controls operation of the
machine. Automatic operation is controlled by a (BLS) bin level switch, which will automatically
stop and start the icemaker by the level of the ice in the storage bin. The program is written so that
the unit will stop only upon the completion of a defrost cycle whether by action of the “Off” position
of the Master switch on the operator interface, or by the bin level switch
The MCS “On” position during normal ice-making operation and the water pump selection to
“Auto”. The pump should only be set to the “Manual” position only when the equipment is to be
cleaned as outlined in the “Cleaning Procedure”, Section 7 and instructions attached to the machine.
If it should become necessary to instantly stop the machine, push the emergency “Stop” button. To
restart the machine, use the MCS on the operator interface.
FIGURES 4-1 & 4-2 illustrate the piping diagram of the refrigerant and water circuits of the Modular
Plate Ice machine with numbers for easy reference. Throughout this manual, the numbers you see in
parentheses refer to the numbers in this piping schematic.
The freezer (1) is a plate bank assembly of 12 plates. During the freezing period, water is constantly
recirculated on the exterior of the plates by a centrifugal pump (11). Make-up water is maintained by
a float valve (15) in the water tank. The electrical circuit opens and closes the liquid line solenoid
valve (2), the defrost solenoid valve (3), sometimes referred to as the “D” valve, the wet suction
solenoid valve (20) and the high pressure liquid feed valve (51).
Refrigerant gas from the freezer (1) passes through the suction accumulator, and to the compressor.
Here the cool gas is compressed to a high temperature, high pressure gas which discharges through
the oil separator and into the condenser. In the condenser, heat is removed and the gas is condensed
to a high temperature, high pressure liquid. The high pressure liquid feeds to the low pressure
receiver (32) through the hand expansion valve (52) to be circulated back to the freezer (1). The cold
liquid is pumped to the Freezer through the liquid line solenoid valve (2). The cold liquid
refrigerant enters the freezer where it absorbs heat from the circulating water. This cool gas is pulled
out of the freezer at the suction outlet thereby completing the circuit.
The freezing period is completed by action of the freeze timer in the control panel. The water pump
(11) is stopped and solenoid valves (2 and 20) are closed. The thawing period then begins. The thaw
gas solenoid valve (3), sometimes referred to as the “D” valve, is partially opened and the harvest
timer (T) is activated. After a brief period the thaw gas valve completely opens. Warm gas from the
compressor is discharged into the freezer through valve (3), thereby slightly thawing the outer edge
of the ice which drops on the ice slide for discharging. See “Freezer Period and Harvest Period” for
more detailed description of operation.
Freeze Period. The Modular Plate Ice machine is frozen on the outside the stainless steel plates in
the freezer (1) by the direct application of refrigerant to the inside of the plate. The ice is produced