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protect against a possible freeze-up if no glycol is in
the coolant. Once the proper glycol solution is
present, adjust the Freezstat to the appropriate
setting.
CAUTION: The manufacturer's warranty does not
cover the evaporator from freezing. It is vital that the
Freezestat is set properly.
Step 6 – Turn On Control Power
Some chillers may have a control power switch. If
present, turn the control power switch on. If not
present, turning the main power on should turn the
control power on. When the control power is on, the
panel displays are illuminated. Due to extreme
ambient temperatures that may occur during
shipment, the High Refrigerant Pressure switch may
have tripped. If this is the case, disconnect the main
power and reset the High Refrigerant Pressure by
depressing the manual reset button located on the
switch. Reconnect the main power, turn the control
power on, and clear the alarm condition by pressing
the Alarm Reset button.
Step 7 – Establish Coolant Flow
Standard units have an internal pump. To energize
the pump press the Start button. If the unit does not
have an internal pump, energize the external pump
to establish flow through the chiller.
Note: The compressor will not start as long as the flow switch is
open. A positive flow through the evaporator is required before the
compressor can operate.
Set water flow using a discharge throttling valve or
flow control valve (by others). The valve should be
the same size as the To Process connection of the
chiller. Standard chillers require approximately 2.4
gpm/ton of nominal capacity. A significant increase
in flow beyond this in a standard chiller may result in
excessive pressure loss and negatively impact chiller
efficiency and in extreme cases may cause premature
wear or damage of internal components.
Step 8 – Intial Unit Operation
Enter the desired leaving fluid temperature on the
control panel. Unless otherwise specified, the chiller
is factory set to deliver coolant at 50°F. Adjust to the
desired operating temperature. The chiller should
now be controlling to the selected temperature.
Please note that if there is insufficient load the
compressor may cycle on and off causing swings in
temperature.
Note: For chillers with the variable-speed compressor option
operating under low load conditions with the compressor speed at
its minimum, the hot gas system will maintain temperature 1°
below setpoint.
WARNING: Never deactivate the High Refrigerant
Pressure or the Low Compressor Pressure switch.
Failure to heed this warning can cause serious
compressor damage, severe personal injury, or death.
Note: For chillers with the variable-speed compressor option there is
an initial startup routine that will run the compressor at a fixed
speed for 2 minutes. After this routine the chiller will actively
manage the system to maintain desired set point.
Operate the system for approximately 30 minutes.
Check the liquid line sight glass. The refrigerant flow
past the sight glass should be clear. Bubbles in the
refrigerant indicate either low refrigerant charge or
excessive pressure drop in the liquid line. Indications
of a shortage of refrigerant are low operating
pressures or subcooling.
Normal subcooling ranges are from 10°F to 20°F. If it
is not, check the superheat and adjust if required.
The superheat should be approximately 10°F. Since
the unit is factory charged, adding or removing
refrigerant charge should not be necessary. If the
operating pressures, sight glass, superheat, and
subcooling readings indicate a refrigerant shortage,
charge refrigerant as required. With the unit running,
add refrigerant vapor by connecting the charging
line to the suction service valve and charging
through the backseat port until operating conditions
become normal.
CAUTION: A clear sight glass alone does not mean
that the system is properly charged. Also, check
system superheat, sub-cooling, and unit operating
pressures. If both suction and discharge pressures are
low but sub-cooling is normal, a problem other than
refrigerant shortage exists. Do not add refrigerant, as
this may result in overcharging the circuit.
After achieving proper flows and temperatures, press
the Stop button. The unit is now ready for service.
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