Unit installation

803 C – 01/05 A – pag. 12/17
Compressor maintenance
The screw Frame 4 compressor does not required frequent maintenance. However, vibration is an excellent check
for proper mechanical operation. Compressor vibration is an indicator of the requirement for maintenance and
contributes to a decrease in unit performance and efficiency. It is recommended that the compressor be checked
with a vibration analyzer at or shortly after start-up and again on an annual basis. When performing the test the
load should be maintained as closely as possible to the load of the original test. The vibration analyzer test
provides a fingerprint of the compressor and when performed routinely can give a warning of impending problems.
The compressor is supplied with a cartridge oil filter. It is a good policy to replace this filter anytime the compressor
is opened for servicing.
Electrical control centre
Warning: Electric shock hazard. Turn off all power before continuing with following service.
Caution: It is necessary to de-energize the complete panel, including crankase heater, before doing any servicing
inside.
Prior to attempting any service on the control centre it is advisable to study the wiring diagram so that you
understand the operation of the water chiller. Electrical components do not require particular maintenance other
than a monthly tightening of cables.
Warning: The warranty becomes void if the wiring is not in accordance with the specification. A blown fuse or
tripped protector indicates a short ground or overload.
Before replacing the fuse or restarting the compressor, the problem must be found and corrected. It is important to
have a qualified control panel electrician service this panel. Unqualified tampering with the controls can cause
serious damage to equipment and void the warranty.
Refrigerant sightglass
The refrigerant sightglasses should be observed periodicaly (a weekly observation should be adequate). A clear
glass of liquid indicates that there is adequate refrigerant charge in the system to insure proper feed through the
expansion valve. Bubbling refrigerant in the sightglass, during stable run conditions, indicates that the system may
be short of refrigerant charge. Refrigerant gas flashing in the sightglass could also indicate an excessive pressure
drop in the liquid line, possibly due to a clogged filter-drier or a restriction eisewhere in the liquid line. If subcooling
is low add charge to clear the sightglass. If subcooling is normal and flashing is visible in the sightglass check the
pressure drop across the filter-drier. An element inside the sightglass indicates the moisture condition
corresponding to a given element color. If the sightglass does not indicate a dry condition after about 3 hours of
operation, the unit should be pumped down and the filter-driers changed.
The following table is a guide to determinate the dry or wet condition of the system:
COLOUR MEANS
Green (Sky Blue) Dry
Yellow (Pink) Wet
Filter-driers
A replacement of the filter-drier is recommended during scheduled service maintenance of the unit, any time
excessive pressure drop is read across the filter-drier and/or when bubbles occur in the sightglass with normal
subcooling. The maximum recommended pressure drop across the filter-drier at 75% to 100% circuit loading is 70
kPa. The maximum recommended pressure drop across the filter-drier at 25% to 50% circuit loading is 35 kPa.
The filter-drier should also be changed if the moisture indicating liquid line sightglass indicates excess moisture by
the wet system color indicators. During the first few months of operation the filter-drier replacement may be
necessary if the pressure drop across the filter-drier exceeds the values listed in the paragraph above. Any
residual particles from the unit heat transfer tubing, compressor and miscellaneous components are swept by the
refrigerant into the liquid line and are caught by the filter-drier.
To change the filter drier, pump the unit down by moving the ON/OFF compressors switches in “off” position.
Move the ON/OFF switch unit Q0 to the “off” position. Turn off all power to the unit and install jumpers across the
terminals.
This jumps out the low pressure control. Close the manual liquid line shutoff valve.
Turn the power of the unit back on and restart the unit by moving the ON/OFF switch unit Q0. The unitwill start
pumping down past the low pressure setting.