York YCAS0130 - Manual (Page 44)

44 YORK INTERNATIONAL
FORM 201.19-NM1 (204)
Commissioning
FIRST TIME START-UP
During the commissioning period
there should be suf fi cient heat load
to run the unit under sta ble full load
op er a tion to enable the unit con trols,
and sys tem op er a tion to be set up cor-
rect ly and a com mis sion ing log tak en.
Be sure that the Micro Panel is prop-
er ly pro grammed (page 166) and the
Sys tem Start-up Check list (page 117)
is com plet ed.
Interlocks
Verify that liquid is fl owing through the evaporator and
that heat load is present. Ensure that any remote run in-
ter 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 mi cro pro ces sor board to
the ‘ON’ position – (Fig. 46, page 130).
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 fi rst com pres sor
starts be cause of the anti-recycle timer). Be ready when
each com pres sor starts, to switch the unit OFF im me -
di ate ly if any unusual noises or other adverse con di tions
de vel op. Use the appropriate emergency stop de vice if
necessary.
Oil Pressure
When a compressor starts, press the rel e vant ‘System
Pressures’ key and verify that oil dif fer en tial pressure
develops immediately (Discharge Pressure minus Oil
Pressure). If oil pressure does not develop, the automatic
controls will shut down the compressor. Un der no cir-
cum stanc es should a restart attempt be made on a com-
pres sor which does not develop oil pres sure im me di ate ly.
Switch the unit switch to the ‘0’ po si tion (OFF).
Refrigerant Flow
When a compressor starts, a fl ow of liquid refrigerant
will be seen in the liquid line sight glass. After several
min utes operation and providing a full charge of re frig -
er ant is in the system, the bubbles will disappear and be
re placed by a solid column of liquid.
Fan Rotation
As discharge pressure rises, the con dens er fans op er ate
in stages to control the pressure. Verify that the fan op-
eration is correct for the type of unit.
Suction Superheat
Check suction superheat at steady full compressor load
only. Measure suction tem per a ture on the copper line
about 6" (150 mm) before the compressor suc tion ser-
vice valve. Measure suction pres sure at the com pres sor
service valve. Superheat should be 10°F to 12°F
(5.6°C to 6.7°C).
Expansion Valve
The electronic expansion valves are factory set and
should not need adjustment.
Economizer Superheat
(Not all models are equipped with economizers)
Check economizer su per heat at steady full com pres sor
load only, under conditions when the econ o miz er sole-
noid is energized. (See Section 1.22, page 134) Measure
gas tem per a ture on the econ o miz er outlet pipe next to the
ex pan sion valve bulb. Mea sure gas pressure at the back
seat port of the economizer ser vice valve. Su per heat as
measured should be 10°F to 12°F (5.6°C to 6.7°C).
Subcooling
Check liquid subcooling at steady full com pres sor
load only. It is important that all fans are run ning for
the sys tem. Measure liquid line temperature on the
copper line beside the main liquid line service valve.
Measure liq uid pressure at the liquid line service valve.
Subcooling should be 12°F to 15°F (6.7°C to 8.3°C).
No bubbles should show in the sight glass. If subcooling
is out of range add or re move re frig er ant as required.
Do not over charge the unit. The liq uid fl ow to the main
evaporator TXV is subcooled fur ther by the econ o miz er,
increasing subcooling to be tween 22°F and 28°F (12°C
and 15°C) at ambients above 90ºF.
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 rect ly, stop the
unit, switch all applicable switch es to the ‘ON’ po si tion
and restart the unit.