York MILLENIUM YCAS Series, Installation Operation & Maintenance, Page: 96 / 156

96
YORK INTERNATIONAL
CHECKING ECONOMIZER SUPERHEAT
(IF APPLICABLE) (15 TON TXV)
The economizer superheat should be checked to assure
proper economizer operation and motor cooling. Cor-
rect superheat setting is approx. 6 - 7°C (10 - 12°F).
The superheat is calculated as the difference between
the pressure at the Economizer Service Valve on the
compressor converted to the corresponding tempera-
ture in a standard pressure/temperature chart and tem-
perature of the gas at the bulb on the entering piping to
the motor housing.
Example:
Motor Gas Temp = 32°C (90°F)
minus Economizer Press
139 PSIG converted
to Temp 26°C (- 78°F)
= 6°C (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
at 6 - 8°C (10 - 15°F).
$
2. Record the suction temperature, suction pres-
sure, suction pressure converted to temperature,
and superheat of each system below:
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 6 - 7°C (10 - 12°F).
$
1. Record the motor gas temperature, economizer
pressure, economizer pressure converted to tem-
perature, and economizer superheat below:
This superheat should only be checked
in an ambient above 32°C (90°F). Oth-
erwise, mid-range adjustment (factory
setting) is acceptable.
LEAK CHECKING
$
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.
SYS 1 SYS 2
Motor Gas Temp = kPa (PSIG)
Economizer Press
= °C (°F)
Temp = °C (°F)
Superheat = °C (°F)
SYS 1 SYS 2
Suction Temp = kPa (PSIG)
Suction Temp = °C (°F)
Temp = °C (°F)
Superheat = °C (°F)
Technical Data