First Time Start-Up - York MILLENNIUM YCAS Installation Operation & Maintenance

FIRST TIME START-UP

During the commissioning period
there should be sufficient heat load to
run the unit under stable full load
operation to enable the unit controls,
and system operation to be set up cor-
rectly and a commissioning log taken.
Be sure that the Micropanel is prop-
erly programmed (page 135) and the
the System Startup Checklist (page 93)
is completed.
Interlocks
Verify that liquid is flowing through the cooler and that
heat load is present. Ensure that any remote run inter-
locks are in the run position and that the run schedule
requires the unit to run or is overridden.
System Switches
Place the 'Sys 1' switch on the microprocessor board
to the 'ON' position - see loading/unloading sequence
on page 129.
Start-Up
Remove the locking device from the unit Auto/OFF
switch which prevents unauthorized starting of the unit
before commissioning. Press the 'Status' key, then turn
the unit switch to the "1" position to start the unit (there
may be a few seconds delay before the first compres-
sor starts because of the anti-recycle timer). Be ready
when each compressor starts, to switch the unit OFF
immediately if any unusual noises or other adverse con-
ditions develop. Use the appropriate emergency stop
device if necessary.
Oil Pressure
When a compressor starts, press the relevant 'System
Pressures' key and verify that oil differential pressure
develops immediately. If oil pressure does not develop,
the automatic controls will shut down the compressor.
Under no circumstances should a restart attempt be
made on a compressor which does not develop oil pres-
sure immediately. Switch the unit switch to the '0' posi-
tion (OFF).
Refrigerant Flow
When a compressor starts a flow of liquid refrigerant
will be seen in the liquid line sight glass. After several
minutes operation and providing a full charge of refrig-
erant is in the system, the bubbles will disappear and be
replaced by a solid column of liquid.
YORK INTERNATIONAL
Fan Rotation
As discharge pressure rises, the condenser fans oper-
ate in stages to control the pressure. Verify that the fan
operation is correct for the type of unit.
Suction Superheat
Check suction superheat at steady full compressor load
only. Measure suction temperature on the copper line
about 150 mm (6") before the compressor suction ser-
vice valve. Measure suction pressure at the compres-
sor service valve. Superheat should be -7ºC to -6ºC (10ºF
to 12ºF).
Economizer Superheat
Check economizer superheat at steady full compressor
load only. Measure gas temperature on the economizer
outlet pipe next to the expansion valve bulb. Measure
gas pressure at the back seat port of the motor cooling
service valve. Superheat as measured should be -7°C
to -6ºC (10ºF to 12ºF).
Expansion Valve Adjustment
The expansion valves are factory set and should not
need adjustment. If any superheat values are out of range,
however, the expansion valve adjusting screw should
be adjusted no more than 1 turn at a time ('in' to in-
crease superheat, 'out' to decrease superheat), allow-
ing at least 10 minutes for the valve to stabilize before
rechecking the value of superheat.
Subcooling
Check liquid subcooling at steady full compressor load
only. It is important that all fans are running for the sys-
tem. Measure liquid line temperature on the copper line
beside the main liquid line service valve. Measure liquid
pressure at the liquid line service valve. Subcooling
should be -8ºC to -7ºC (12ºF to 15ºF). No bubbles should
show in the sight glass. If subcooling is out of range add
or remove refrigerant as required. Do not overcharge
the unit. The liquid flow to the main cooler TXV is
subcooled further by the economizer, increasing
subcooling to between -15ºC and -12ºC (22ºF and 28ºF).
General Operation
After completion of the above checks for System 1,
stop the unit, switch OFF the 'SYS 1' switch on the
main panel microprocessor board and repeat the pro-
cess for each subsequent system. When all run cor-
rectly, stop the unit, switch all applicable switches to the
'ON' position and restart the unit.
FORM 201.18-NM2
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