Unit Start-Up; Checks To Be Made During Start-Up - Lennox WA Series Installation, Operating And Maintenance

UNIT START-UP

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 §8.3 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).
Installation - Operation - Maintenance manual (IOM) • AIR COOLED CHILLERS & SPLIT UNITS - 1106-E
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