York MILLENNIUM YCUL0016SC, Assembly, Installation, Operation & Maintenance

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YORK INTERNATIONAL
94
The subcooling should be adjusted to 15°F at design
conditions.
G
1. Record the liquid line pressure and its corre-
sponding temperature, liquid line temperature
and subcooling on the lines below:
SYS 1 SYS 2
Liq Line Press = _______ _______ PSIG
Saturated Temp = _______ _______ °F
Liq Line Temp = _______ _______ °F
Subcooling = _______ _______ °F
After the subcooling is verified, the suction superheat
should be checked. The superheat should be checked
only after steady state operation of the unit has been
established, the discharge air temperature (or suction
pressure) has been pulled down to within the control
range, and the unit is running in a fully loaded condition.
Correct superheat setting for a system is 10°F (5.56°C)
18" (46 cm) from the evaporator.
The superheat is calculated as the difference between
the actual temperature of the refrigerant gas in the suc-
tion line and the temperature corresponding to the suc-
tion pressure as shown in a standard pressure/tempera-
ture chart.
Example:
Suction Temp = 46°F
minus Suction Press
60 PSIG converted to Temp - 34°F
Superheat = 12°F
When adjusting the expansion valve, the adjusting screw
should be turned not more than one turn at a time, allow-
ing sufficient time (approximately 15 minutes) between
adjustments for the system and the thermal expansion
valve to respond and stabilize.
Assure that superheat is set at 10°F (5.56°C).
G
2. Record the suction temperature, suction pres-
sure, suction saturation temperature, and super-
heat of each system below:
SYS 1 SYS 2
Suction temp = _______ _______ °F
Suction Pressure = _______ _______ PSIG
Saturation Temp = _______ _______ °F
Superheat = _______ _______ °F
LEAK CHECKING
G
1. Leak check compressors, fittings, and piping to
assure no leaks.
If the unit is functioning satisfactorily during the initial
operating period, no safeties trip and the compressors
cycle to control discharge air temperature (or suction
pressure) the chiller is ready to be placed into opera-
tion.
Initial Startup