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Initial Startup
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 =
minus Suction Press
60 PSIG converted to Temp
Superheat =
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
94
46°F
- 34°F
12°F
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 pressure,
suction saturation temperature, and superheat of
each system below:
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 pres-
sure), the chiller is ready to be placed into operation.
SYS 1
SYS 2
YORK INTERNATIONAL
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