MAINTENANCE
CHILLER-IOM-2004-E
44
MAINTENANCE PLAN
Task
Operating mode
Monthly
+
Quarterly
Half
Yearly
Check refrigeration system for
proper functioning (Thermal
expansion valve)
Retrieve/Check the values for superheating and sub cooling.
Resume the expansion valve settings when needed, verify the
behavior in partial loads and at 100%. Resume settings to obtain
superheat between 5K and 10K.
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Check refrigeration system for proper
functioning (Electronic expansion
valve)
Retrieve/Check the values of the pressure and temperature
sensors. Check also for the good behavior of the expansion valve
(Open/closed) in full load and partial load conditions. The
superheat must be between 5K an 8K.
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Check the position and
tightness of refrigeration
components
Check systematically all connections and fixings on the
refrigeration circuit. Check for oil traces, eventually a leak test
should be conducted. Check operating pressures correspond to
the ones indicated on the commissioning sheet.
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SIGHT GLASS (when applicable)
The liquid refrigerant flow through the sight glass should be
steady and without bubbles. Bubbles are a sign of a low charge, a
possible leak, or of a restriction in the liquid line. Each sight glass
is fitted with a humidity indicator. The color of the element
changes according to the level of humidity in the refrigerant, also
according to the temperature. It should indicate «dry» refrigerant.
If it shows «wet» or
«CAUTION», contact a qualified refrigeration technician.
CAUTION:
when starting up the unit, run the compressor for at
least 2 hours before taking a humidity reading. The humidity
detector is also sensitive to temperature, and as a consequence,
the system must be at normal operating temperature to give a
meaningful reading.
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Check antifreeze protection
Test antifreeze function (leakage rate, frost protection thermostat)
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Check refrigeration 3-way valve
Check the proper functioning of the system.
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Check tightness of all
electrical connections
Power down the unit and check and tighten all the screws,
terminal and electric connections (including the terminal boxes)
When turning on the unit, check for the deterioration of the
electrical components with a thermal camera while the unit is
working at 100% of its power.
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Check HP / LP safety switches
Install a pressure gauge HP / LP and check if the safety switches
for its overall working.
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Check the position of all sensors
Check the position and the fixation of all sensors.
•
Check anti-vibration mountings, for
wear and tear.
Visually check anti-vibration mountings on compressors and
centrifugal fan. Replace it, if damaged.
•
Check Glycol concentration in the
water circuit
Check the glycol concentration in the pressurized water circuit. ( a
concentration of 30% gives a protection down to approx.. -15°C)
check the circuit pressure
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Check casing and equipment
corrosion
To treat and neutralize eventual rust spots
•
Check the water pump
When the unit is operated with glycol up to 20% and the water
temperature below -5°C, even if you use a specific thermal
protection for the pump, it is advisable to clean the body of the
pump every 18 months in order to avoid leaks by crystallization.
(see supplier catalogue)
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Plate exchanger
Verify the general insulation state, the tightness of the water
connection and the freeze protection.
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Check the expansion vessel (if
applicable)
Measure the pressure under the different water modes ( from
+7°C to +45°C)
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Check the software version
Contact the manufacturer for updates
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