Operation - Scotsman DCE33 User Manual

OPERATION

How does the machine make ice?
There are two distinct cycles: freeze and harvest.
1 freeze cycle + 1 harvest cycle = 1 batch of 8
cubes.
The Freeze cycle happens when water is sprayed
against the freezing surface. The Harvest cycle is
when the ice is released and water enters the
machine. A complete cycle takes about 30
minutes.
Freeze: During the freeze cycle the compressor is
pumping refrigerant, the fan motor is blowing air,
and the water pump is circulating water. As the
refrigerated surface absorbs heat from the water
sprayed against it, that heat is moved to the area
where the fan is blowing air. The heat is
transferred to the air, and the warmed up air is
discharged from the ice machine. At the same time
ice is forming on the refrigerated surface (located
at the upper back of the machine). When the
refrigerated surface gets cold enough, the ice
machine's timer will begin to turn. When it turns far
enough, it will stop the freeze cycle and begin the
harvest.
Schematic Diagram - Shown In
Harvest Cycle
Compressor
Harvest: During the harvest cycle the compressor
is still operating, but the spray pump and fan motor
have stopped. Two other components have been
energized; the hot gas valve and the inlet water
valve. These two valves open and warm up the
freezing surface, allowing the cubes to fall into the
bin. The timer is still turning, and when it gets to
the end of the harvest cycle, the freeze cycle will
restart.
How does the machine use water? The ice
machine begins with a fixed charge of water that is
contained in the reservoir. As the water is sprayed
against the freezing surface, the part of water that
does not contain mineral impurities will freeze and
stick to the ice cup molds. The water containing
impurities falls back into the reservoir. Gradually,
during the freezing portion of the ice making cycle,
the water in the reservoir will become highly
concentrated with mineral impurities.
During the harvest cycle fresh water flows into the
machine to dilute the reservoir water and to rinse
the concentrated minerals down the drain.
Evaporator
August 1995
Page 13
Water
Inlet
Cube Molds
DCE33
Weep
Hole
Spray Jets
Water Tube
Reservoir
Condenser