Vogt TUBE-ICE 05TA, Service Manual

Page: 65 / 111

05TA Service Manual
SERVICE OPERATIONS
8/13/01
9-1
9. Service Operations
Adjustable Blowdown (for clearer ice).
A petcock is installed on the overflow of the water pump
to provide means for obtaining blowdown from the water tank during the freezing period. The
petcock was set at the factory to discharge enough water during the freeze cycle to produce clear ice.
After installation it should be adjusted to the minimum rate required to maintain clear ice and checked
after a few days of ice making.
Automatic Blowdown (Harvest Cycle).
A feature of this machine is the automatic blowdown (40)
which is provided to eliminate or reduce the necessity for frequent flushing or cleaning of the water
tank (7) and to remove accumulated salts or solids in the water as a result of the freezing action.
During the harvest water returning from the freezer raises the tank level and causes an overflow of
water which create a siphon to remove a fixed amount of water from the tank.
Float Valve (make-up water).
The make-up 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 by-pass or blowdown only during the
thaw mode. The water level during the freeze mode should always be below the by-pass 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 drain by-pass.
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 “A” 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 “A” 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 that provides highest capacity. The correct height will
produce compressor superheat which climbs throughout the freeze cycle to a minimum of 30° F.
Hand Expansion Valve.
The hand expansion valve is located after the “A” solenoid valve. This
valve should be set at a point where the float switch is open for a length of time approximately equal
to the time it is closed.
Freezer Pressure Switch. The freezer pressure switch (FPS), located inside the control panel,
controls the freezing time period for the production of cylinder or crushed ice.