Quantech QCC2015CEE Installation, Operation And Maintenance Manual page 101

Form QCC2-NM1
Issue Date: 5/20/2021
D. CHECKING SUPERHEAT AND SUBCOOLING
The subcooling temperature of each system can
be calculated by recording the temperature of the
liquid line at the outlet of the condenser and sub-
tracting it from the liquid line saturation tempera-
ture at the liquid stop valve (liquid line saturation
temp. is converted from a temperature/pressure chart).
Example:
Liquid line pressure =
202 PSIG converted to temp.
minus liquid line temp.
Subcooling =
The subcooling should be adjusted to 18°F at design condi-
tions.
1. Record the liquid line pressure and its corre-
sponding temperature, liquid line temperature and
subcooling below: ....................................................
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 condensing
unit has been established, the leaving water tempera-
ture has been pulled down to the required leaving wa-
ter temperature, and the unit is running in a fully loaded
condition. Correct superheat setting for a system is 10°F
to 15°F (5.56°C to 8.33°C) 18" (46 cm) from the cooler.
Superheat should typically be set for no less than
10°F with only a single compressor running on a
circuit. The superheat is calculated as the difference
between the actual temperature of the returned refrig-
erant gas in the suction line entering the compressor
and the temperature corresponding to the suction pres-
sure as shown in a standard pressure/temperature chart.
Example:
Suction Temp =
minus Suction Press
60 PSIG converted to Temp - 34°F
Superheat =
P.O. Box 1592, York, Pennsylvania USA 17405-1592
Copyright © by Johnson Controls 2013
Form 150.63-CL2 (1013)
Issue Date: October 31, 2013
QUANTECH
NEW RELEASE
102°F
- 84°F
18°F
SYS 1 SYS 2
46°F
12°F
800-861-1001
www.johnsoncontrols.com
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.
Assure 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
Suction Temp = _______ _______ °F
Suction Pressure = _______ _______ PSIG
Saturation Temp = _______ _______ °F
Superheat = _______ _______ °F
E. LEAK CHECKING
Leak check compressors, fittings, and piping to en-
sure no leaks. ..............................................................
If the unit is functioning satisfactorily during the ini-
tial operating period, no safeties trip and the com-
pressors cycle to control water temperature to
setpoint, the chiller is ready to be placed into operation.
Owner's operating personnel:
Name:
___________________________________________________
Phone Number:
__________________________________________
Name:
___________________________________________________
Phone Number:
__________________________________________
Name:
___________________________________________________
Phone Number:
__________________________________________
Subject to change without notice. Printed in USA
SECTION 6 – COMMISSIONING
FORM 150.63-CL2
ISSUE DATE: 10/31/2013
SYS 2
ALL RIGHTS RESERVED
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