• 22 • Installation - Operation - Maintenance manual (IOM) • AIR COOLED CHILLERS & SPLIT UNITS - 0105-E
5 - UNIT START-UP
5.1 - CHECKS TO BE MADE DURING START UP
5.1.1 CHECKS TO BE MADE DURING START UP
Before starting the unit, fill in the check list sheet on page 48 of this manual and follow the instructions below to be
sure that the unit is correctly installed and ready to operate.
1) Thermometers and pressure switches installed in the chilled water circuit and the condenser water circuit.
Check these safety devices in this order: high pressure switch, differential oil pressure switch, low pressure
switch, fan control pressure switches and thermostats, anti short cycle relay. Make sure all indicator lights
operate correctly.
2) Run evaporator pump prior to start the chiller.
3) Flow switch installed and wired into the control box operates properly.
4) With the compressor running, check the oil pressure. If there is a fault, do not restart the compressor again until
the source of the problem has been located.
5) Check that there is sufficient cooling load on the day the start up is conducted (at least 50 % of the nominal load).
PROCEDURE TO FOLLOW WHEN STARTING THE UNIT
5-a) Press the power "ON-OFF" switch. The compressor will only start if the evaporating pressure is greater than
the cut-in set point of the low pressure switch.
Check immediately the good rotation of the compressor.
Evaporating pressure drops steadily, the evaporator empties itself of the liquid refrigerant accumulated in
it during storage. After a few seconds, the solenoid valve opens if any.
5-b) Check on the sightglass (upstream of the expansion valve) that the bubbles disappear progressively,
indicating a correct refrigerant charge and without non condensable gas. If the humidity indicator changes
colour, indicating the presence of humidity, replace the filter-drier cartridge if the latter is of the replaceable
type. Even better, check the sub cooling after the condenser.
5-c) Check that, when the cooling load has been balanced by the capacity of the unit, the chilled liquid is at design
temperature.
6) Check the current values per phase on each compressor motor.
7) Check the current values per phase on each fan motor.
8) Check compressor discharge temperature.
9) Check compressor oil pump temperatures (semi-hermetic reciprocating compressors).
10)Check suction and discharge pressures and compressor suction and discharge temperatures.
11)Check chilled liquid entering and leaving temperatures.
12)Check outdoor air temperature.
13)Check liquid refrigerant temperature at the condenser outlet.
These verifications should be made as quickly as possible with a stable cooling load, i.e. the cooling load of the
installation should be the same as the capacity developed by the unit. Measurements taken without heeding this
condition will result in unusable and probably wrong values.
UNIT START-UP
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