Schreiber Chillers Modular Chillers - Manual (Page 28)

28
SPECIAL INSTRUCTIONS
ELECTRICAL CONTROLS- Control Circuit 24 Volts
The high-pressure switch will shut off the refrigeration system in the event the
pressure is too high. High pressure can be caused by the condenser becoming
restricted, by foreign material on the outside surface of the condenser, or if the fan
motor is not running. If the high-pressure limit switch should cut out, there is a
manual reset switch, which is located at the control panel on the right side. In order
to reset this switch, the disconnect switch and the switch must be turned off and the
control panel door must be open. If and when the high-pressure switch is cut out
occurred, check the “Trouble Shooting” chart for diagnosis.
The low-pressure switch will cut out at any time the pressure in the refrigeration system is
below 25 psi. Low psi can be caused by a freeze up in the water tank, a leak in the
refrigeration system, if the system is low on Freon (R-22), or if there is any sort of
restriction in the system. If the switch cuts out, it will automatically reset. Never try to
adjust the high and low-pressure switches or by-pass them, or serious damage to
the system will result. Adjustment should only be made after the internal pressure of
the refrigeration system has been read.
The second control of the circuit is the temperature controller. It controls the cycling of the refrigeration
system. Once this control is set, it will control the cycling of the unit automatically. Do not set it below
freezing unless the proper amount of antifreeze is put into the unit. Since antifreeze is a poor conductor of
heat, never add more than necessary.
The third control on the circuit is the compressor switch. It is used to OPERATE the refrigeration system.
The fourth part on the circuit is motor overload protected. Every motor is equipped with an internal overload
or external over-current protection. Motor overload cut out can be due to various reasons. In most cases, it
is either caused by over or under supply voltage.
REFRIGERATION SYSTEM:
The refrigeration system is a medium temperature system with a range from 35 o F to 70 o F evaporating
temperature. The design saturation-condensing Temp is 120
o
F, with 10
o
F sub cooling. The saturation-
evaporating Temp is 32
o
F with 15
o
F superheated. If temperatures below or above this range are required, they
should be discussed with our engineering department. The refrigeration system also includes a hermetically
sealed refrigeration system and all parts, except the evaporator coil, are standard to the refrigeration industry.
The evaporator coil is installed in a stainless steel tank and this reservoir provides a thermal buffer for better
control of water temperature and causes the water flow not to be restricted, resulting in better water circulation.
A qualified refrigeration company or technician that should do any repairs to the refrigeration system. Schreiber
Engineering will always have a service engineer available to answer any questions regarding chiller service.
This unit has a service valve on the suction and discharge line. The suction line has its valve on the suction
line. The high pressure or discharge service line is on the discharge gas line.
This unit is charged with R-22. DO NOT OVERCHARGE because this will cause damage to the compressor.
The refrigeration sight glass is fuzzy until the unit reaches its proper temperature and has been properly
charged.
MAINTAINING THE CHILLER:
Very little maintenance is required on this unit. It might be necessary to clean out the heat exchanger located
within the water tank, only depending on the condition of the water used in the chilled water circuit. It might also
be necessary to blow out the condenser from time to time, depending on the environment of the installed unit.
Finally, the water-cooled condenser needs to be flushed out once in a while. The frequency of this process
depends on the condition of the condenser’s water supply.