York YCAL Series, Установка, эксплуатация и обслуживание

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FORM 150.66-NM3
ISSUE DATE: 09/25/2020
43
JOHNSON CONTROLS
SECTION 5 - COMMISSIONING
55
CHECKING SUPERHEAT AND SUBCOOLING
The subcooling temperature of each system can be cal-
culated by recording the temperature of the liquid line
at the outlet of the condenser and subtracting it from
the liquid line saturation temperature at the liquid stop
valve (liquid line saturation temp. is converted from a
temperature/pressure chart).
Example:
Liquid line pressure =
328 psig converted to temp. 102°F
minus liquid line temp. - 87°F
Subcooling = 15°F
The subcooling should be adjusted to 15°F at design
conditions.

1. Record the liquid line pressure and its correspond-
ing temperature, liquid line temperature and
subcooling 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 chiller has been es-
tablished, the leaving water temperature has been pulled
down to the required leaving water temperature, and the
unit is running in a fully loaded condition. Correct su-
perheat setting for a system is 10°F to 15°F (5.56°C to
8.33°C) 18” (46 cm) from the cooler.
Set superheat for no less than 10°F with only a sin-
gle compressor running on a circuit. The superheat
is calculated as the difference between the actual tem -
perature of the returned refrigerant gas in the suction
line entering the compressor and the temperature cor-
responding to the suction pressure as shown in a stan-
dard pressure/temperature chart.
E
xample:
Suction Temp = 46°F
minus Suction Press
106 psig converted to Temp - 34°F
Superheat = 12°F
When adjusting the expansion valve (TXV only), the
adjusting screw should be turned not more than one
turn at a time, allowing sufficient time (approximately
15 minutes) between adjustments for the system and
the thermal expansion valve to respond and stabilize.
The EEV is non­adjustable. Superheat
setpoint is programmable from the
keypad.
Ensure that superheat is set at a minimum of 10°F (5.56°C)
with a single compressor running on each circuit.

2. Record the suction temperature, suction pressure,
suction saturation temperature, and superheat of
each system below:
SYS 1 SYS 2
Suction Temp = _______ _______ °F
Suction Pressure = _______ _______ PSIG
Saturation Temp = _______ _______ °F
Superheat = _______ _______ °F
LEAK CHECKING

1. Leak check compressors, fittings, and piping to
ensure no leaks.
If the unit is functioning satisfactorily during the ini-
tial operating period, no safeties trip and the compres-
sors cycle to control water temperature to setpoint, the
chiller is ready to be placed into operation.