Vogt HEC-10, Service Manual

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HEC-Series Service Manual
HOW YOUR TUBE-ICE MACHINE WORKS
10/21/01
4-5
Ice Bin Capacity. Crushed or cylinder ice weighs approximately 35 pounds per cubic ft. (35 lb/ft
3
).
As ice drops into a bin, it will pile up and slope naturally at about a 45° angle. This natural slope
should be taken into account when locating the bin thermostat bulb (or other bin level control) and
when calculating the normal bin capacity. If the ice is spread out by hand in the bin for maximum
storage capacity, make sure a hazard is not created by allowing ice to back up into the chute and
jamming the cutter. Always allow enough room below the chute for at least one harvest (approx. 40
lbs. of ice).
If a two-way defector is installed below the ice chute, care should be taken to make sure it is located
directly in the center of the stream of ice as it falls to give even distribution of the ice.
Refrigeration System (Review Before Starting Machine).
The refrigeration system uses HCFC-
22 refrigerant, a compressor, a thermal expansion valve, a flooded evaporator (freezer), and warm
gas defrost. Following the schematic, you see that during the freeze period of the machine’s cycle,
the compressor discharge gas leaves the compressor and goes to the condenser where it is condensed
into a liquid by the removal of heat by either air or water passing through the condenser. A reservoir
of liquid is accumulated in the receiver and flows as required, passing through the filter/drier, then the
thawing chamber, (a lower separate section of the freezer). The liquid solenoid valve (the “A” valve)
being open during the operation allows the liquid to be metered by the thermal expansion valve that
opens and closes (modulates) as the temperature of the suction line dictates. The evaporator floods
with wet refrigerant that is in contact with the outside of the tubes that the ice-making water is being
circulated through. The heat contained in this water is conducted through the wall of the tubes,
lowering the temperature of the water, causing it to freeze and form a long tube of ice that adheres to
the inside of each of the freezer tubes. The flowing water keeps the accumulated ice clear by washing
separated solids down into the sump area of the water tank.
The wet suction gas leaves the freezer, passes through the accumulator, and has any remaining liquid
droplets removed by the heat contained in the high side liquid passing through the heat exchanger.
The dry gas enters the compressor and is compressed then discharged to the condenser, the
condensed liquid flows through the liquid side of the heat exchanger and to the receiver completing
the cycle.
As the ice is formed in the freezer, the suction pressure steadily reduces until it causes one of the
freezer pressure switches to close and switch the machine to a harvest period.
During the harvest period, the thawing gas solenoid valve, (The “D” valve), is open allowing the
warm high pressure gas to enter the freezer. This heat melts a thin film from the outside of the ice,
reducing the diameter and letting it fall free from the freezer tubes. The flow of thaw gas through the
freezer is controlled by the CPR (crankcase pressure regulator) valve. This valve should be set as
recommended in TABLE 9-2, “CPR Valve Setting”.
For additional information and familiarization, see “How Your Tube-Ice Machine Works,” Page 4-1,
and Piping Schematics, FIGURES 4-1, 5-7, & 5-3.