York Millennium YCAS 216X, Installation Operation & Maintenance

Page: 136 / 144

136
YORK INTERNATIONAL
CHECKING ECONOMIZER SUPERHEAT
(15 TON TXV)
The economizer superheat should be checked to assure
proper economizer operation and motor cooling. Correct
superheat setting is approx. 10 - 15°F.
The superheat is calculated as the difference between
the pressure at the Economizer Service Valve on the
compressor converted to the corresponding temperature
in a standard pressure/temperature chart and tempera-
ture of the gas at the bulb on the entering piping to the
motor housing.
Example:
Motor Gas Temp = 90°F
minus Economizer Press
139 PSIG converted
to Temp - 78°F
12°F
Normally, the thermal expansion valve need not be ad-
justed in the field. If however, adjustment needs to be
made, the expansion valve adjusting screw should be
turned not more than one turn at a time, allowing suffi-
cient time (approximately 15 minutes) between adjust-
ments for the system and the thermal expansion valve
to respond and settle out. Assure that superheat is set
between 10 -15°F.
q
1. Record the motor gas temperature, economizer
pressure, economizer pressure converted to tem-
perature, and economizer superheat below:
SYS 1 SYS 2
Motor gas Temp = _______ _______ °F
Economizer Pressure = _______ _______ PSIG
Economizer Temp = _______ _______ °F
Superheat = _______ _______ °F
NOTE: This superheat should only be checked in an
ambient above 90°F. Otherwise, mid-range ad-
justment (factory setting) is acceptable.
5 TON TXV SUPERHEAT SETTING
The 5 Ton TXV Superheat does not require checking. It
should typically operate at 10 - 15°F. Since it is difficult
to check, the factory set “mid-range adjustment” is ac-
ceptable.
LEAK CHECKING
q
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
load and unload to control water temperature, the chiller
is ready to be placed into operation.