Vogt P-24AL, Service Manual

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P24AL & P34AL Service Manual
SERVICING OPERATIONS
12/2016
9-1
9. Servicing Operations
Automatic Blowdown (harvest cycle). A feature of this machine is a solenoid activated flushing
valve (63) which is provided to eliminate or reduce the necessity for frequent flushing or cleaning of
the water tank. This flushing during the harvest cycle helps to remove salts or solids accumulated in
the water as a result of the freezing action. It also helps melt ice chips that fall into the water tank
during harvest. The flushing valve is opened (energized) during each thaw cycle when the water
pump stops and the water in the freezer tubes returns to the water tank. If water quality is superior,
this blowdown can be reduced by installing a smaller reducer bushing in the outlet elbow.
The flushing action carries accumulated salts, solids, and ice chips (fines) out through the water tank
overflow pipe. This overflow should be kept open at all times to allow the water to drain freely and
keep the water level below the cutter disc and ice discharge opening. If the flushing solenoid valve
leaks through during the freeze cycle, it can be disassembled and cleaned, then reassembled.
Cleaning Ice Making Section. Refer to Chapter 7, Maintenance for instructions for cleaning the
circulating water tubes, water distributors, and water tank.
Float valve (make-up water). The make-up water float valve (12) maintains the proper pumping
level in the water tank for ice making. The valve should be set to maintain a water level in the water
tank during the freezing period, so that there will be a quantity of blow down only during the thaw
mode. The water level during the freeze mode should always be below the overflow piping to
prevent excessive waste of cold water, resulting in loss of ice capacity.
If it should become necessary to clean the float valve, close the stop valve in the make-up water line
to the machine and remove the float valve. After the valve has been cleaned and reinstalled, check to
ascertain if the proper water level is being maintained. After the machine is stopped and the water in
the tank seeks its normal level, there should be no water flow through the float valve or out the
overflow.
It is advisable to install a large area strainer in the water supply line to protect the float valve from
dirt or solids in the water which would necessitate frequent cleaning. A strainer of 40-mesh screen is
usually satisfactory.
Float Switch. The float switch is installed on a header assembly that is attached to the freezer shell.
Valves are provided for isolation of the float switch assembly if replacement or servicing is
necessary. The float switch closes as the level of refrigerant in the freezer rises and opens as the
level falls.
The float switch is connected to the “A1” solenoid valve coil. This is the solenoid valve directly
before the hand expansion valve. Therefore, when the refrigerant level in the freezer drops, the float
switch closes, thereby energizing and opening the “A1” liquid feed solenoid until sufficient level has
been reached to open the float switch. The float switch has a fixed 1/2” differential.
The float switch is installed at the correct height at the factory and should not need to be adjusted.
The float switch is installed at the position which provides highest capacity. The correct height will
produce compressor superheat which climbs throughout the freeze cycle to a minimum of 30° F.