Operating instructions

52
7.3.12 - Inspect the heat exchanger tubes
Cooler
Inspect and clean the cooler tubes at the end of the first
operating season. Because these tubes have internal ridges,
a rotary-type tube cleaning system is necessary to fully
clean the tubes. Upon inspection, the tube condition will
determine the scheduled frequency for cleaning and will
indicate whether water treatment is adequate in the chilled
water/brine circuit. Inspect the entering and leaving chilled
water temperature sensors for signs of corrosion or scale.
If a sensor or the probe connections are scaled or the water
flow control probes are corroded, they should be changed.
Verify the flow and speed with the data in the Electronic
Catalogue selection program for the unit.
Condenser
Since this water circuit is usually an open system, the tubes
may be subject to contamination and scale. Clean the
condenser tubes with a rotary tube cleaning system at least
once per year and more often if the water is contaminated.
Inspect the entering and leaving condenser water sensors
for signs of corrosion or scale. Replace the sensor if corroded
or remove any scale if found.
Verify the flow and speed with the data in the Electronic
Catalogue selection program for the unit.
Higher than normal condenser pressures, together with the
inability to reach full refrigeration load, usually indicate dirty
tubes or the presence of air in the chiller. If the refrigeration
log indicates a rise above normal condenser pressures, check
the condenser refrigerant temperature against the leaving
condenser water temperature. If this reading is more than
what the design difference is supposed to be, then the
condenser tubes may be dirty or water flow may be incorrect.
Because HFC134-a is a high-pressure refrigerant, air usually
does not enter the chiller. In certain cases where a zinc
anode (option) is used, regularly check its condition.
During the tube cleaning process, use brushes especially
designed to avoid scraping and scratching the tube wall.
Contact your Carrier representative to obtain these brushes.
Do not use wire brushes.
CAUTION: Scale may require chemical treatment for its
prevention or removal. Consult a water treatment specialist
for proper treatment.
7.3.13 - Water leaks
Water is indicated during chiller operation by the refrigerant
moisture indicator (see Fig. 2 - “19XR machine components”)
on the refrigerant motor cooling line. Water leaks must be
repaired immediately.
CAUTION: Chiller must be dehydrated after repair of
water leaks. See chapter 4.4 “Chiller dehydration”.
7.3.14 - Water treatment
Untreated or improperly treated water may result in
corro-sion, scaling, erosion, or algae. The services of a
qualified water treatment specialist should be obtained to
develop and monitor a treatment programme.
CAUTION: Water must be within design flow limits, clean,
and treated to ensure proper chiller performance and reduce
the potential of tube damage due to corrosion, scaling,
erosion, and algae. Carrier assumes no responsibility for
chiller damage resulting from untreated or improperly
treated water.
7.3.15 - Inspect the starting equipment
Before working on the electrical equipment, shut off the
chiller. Ensure that no circuit is energised and that all are
isolated by a main disconnect switch.
The specific maintenance instructions for starting equipment
for 19XRV machines are given in the appendix, starting
with chapter 8.
Check the cable tightness.
7.3.16 - Check pressure transducers
Once a year, the pressure transducers should be checked
against a pressure gauge reading. Check all four transducers:
the two oil differential pressure transducers, the condenser
pressure transducer, and the cooler pressure transducer, and
the water-side evaporation probes (two on the condenser
and two on the evaporator).
Note the evaporator and condenser pressure readings on the
ICVC 'HEAT-EX' status screen. Attach an accurate set of
refrigeration gauges to the cooler and condenser Schrader
fittings. Compare the two readings. If there is a difference
in readings, the transducer can be calibrated, as described in
the Troubleshooting Guide in the controls manual. Oil
differential pressure should be zero whenever the compressor
is off.
7.3.17 - Corrosion control
All metallic parts of the unit (chassis, casing panels, control
boxes, heat exchangers etc.) are protected against corrosion
by a coating of powder or liquid paint. To prevent the risk
of blistering corrosion that can appear when moisture
penetrates under the protective coatings, it is necessary to
carry out periodic checks of the coating (paint) condition.