QUANTECH
138
FORM QTC3-NM1
ISSUE DATE 08/03/2022
SECTION 7 – UNIT CONTROLS
C H I L L E D L I Q U I D
G L Y C O L
The chilled liquid is glycol. The Cooling Setpoint can
be programmed from 10°F to 70°F (-12.2°C to 21.1°C).
Option 4 – Ambient Control Type
A M B I E N T C O N T R O L
S T A N D A R D
The low ambient cutout is adjustable from 25°F to 60°F
(-3.9°C to 15.6°C).
or
A M B I E N T C O N T R O L
L O W A M B I E N T
The low ambient cutout is programmable down to
-10°F (-23.3°C). A low ambient kit and variable
speed fans MUST be installed for this option to be
chosen. If the kit is NOT installed, and low ambi-
ent is selected, low pressure faults and compressor
damage may occur.
Option 5 – Local/Remote Control Type
L O C A L / R E M O T E M O D E L
L O C A L
When programmed for LOCAL, an ISN or RCC con-
trol can be used to monitor only. The micro panel will
operate on locally programmed values and ignore all
commands from remote devices, or through the RS-
485 inputs. The chiller will communicate and send data
to the remote monitoring devices.
or
L O C A L / R E M O T E M O D E
R E M O T E
This mode should be selected when an ISN or RCC
control is to be used to control the chiller. This mode
will allow the ISN to control the following items: Re-
mote Start/Stop, Cooling Setpoint, Load Limit, and
History Buffer Request. If the unit receives no valid
ISN transmission for 5 min, it will revert back to the
locally programmed values.
Option 6 – Unit Control Mode
C O N T R O L M O D E
R E T U R N L I Q U I D
Unit control is based on return chilled liquid temp.
Return Chilled Liquid Control can only be selected on
units that have 4 to 6 compressors (dual system units).
or
C O N T R O L M O D E
L E A V I N G L I Q U I D
Option 7 – Display Units
D I S P L A Y U N I T S
I M P E R I A L
This mode displays system operating values in Impe-
rial units of °F or psig.
or
D I S P L A Y U N I T S
S I
This mode displays system operating values in Scien-
tific International Units of °C or barg.
Option 8 – Lead/Lag Type (two system units
only)
L E A D / L A G C O N T R O L
M A N U A L S Y S 1 L E A D
SYS 1 selected as lead compressor. SYS 1 lead option
MUST be chosen if Hot Gas Bypass is installed.
or
L E A D / L A G C O N T R O L
M A N U A L S Y S 2 L E A D
SYS 2 selected as lead compressor.
or
L E A D / L A G C O N T R O L
A U T O M A T I C
Lead/lag between systems may be selected to help
equalize average run hours between systems on chillers
with 2 refrigerant systems. Auto lead/lag allows auto-
matic lead/lag of the two systems based on an average
run hours of the compressors in each system. A new
lead/lag assignment is made whenever all compressors
shut down. The microprocessor will then assign the
“lead” to the system with the shortest average run time.
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