Vogt TUBE-ICE P-118F, Service Manual

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P118F Service Manual
SERVICE OPERATIONS
1/6/09
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. This
supplements the blowdown that is discharged during the thawing period through the bypass piping
connected to the drain of the water tank. (See “Automatic Blowdown” below).
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
production of 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) to remove accumulated salts or solids in the water as a result of the freezing action and to
provide for clearer ice production.
At the beginning of a harvest cycle water will return from the freezer causing the level to rise in the
water tank and blowdown piping. When a sufficiently high water level has been reached the
overflow piping will begin to siphon water from the tank. This siphoning will continue until the
tank is dry or the siphoning vacuum is broken. A vacuum break solenoid is installed on the
blowdown piping to break the siphon at the end of the freeze cycle. This valve is normally open and
is only closed during the harvest cycle.
Earlier models did not utilize a siphon to achieve the desired blowdown during harvest. Those
models had a solenoid operated drain valve which would allow the water to drain from the tank
during the harvest cycle.
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.