17
SECTION 1 - INSTALLATION
FORM 145.10-IOM4
ISSUE DATE: 2/27/2019
2
SEQUENCE OF OPERATION: FUNCTIONAL
CHECK
This condensing pressure control package is designed
to maintain a minimum refrigerant liquid pressure of
260 psig, which is sufficient to ensure proper expan-
sion valve operation under all normal conditions. The
electronic proportional control module generates a 0 to
10 VDC output signal based on sensed pressure. This
output signal modulates the condenser air volume, from
0–100%, via an electrically motorized intake damper.
The C450 controller is factory configured for reverse
acting mode. The analog signal output increases as
the sensed pressure drops. Dashed areas in Figure 14
on page 17 show throttling range possibilities from
minimum to maximum.
LD26871
FIGURE 14 - LADK/VADK C450 CONTROLLER
REVERSE ACTING
LD26872
FIGURE 15 - WIRING TERMINAL DETAILS FOR C450 CONTROLLER WITH ANALOG OUTPUTS
The control setpoint is factory set at 360 psig with a
100 psi throttling range.
If outdoor air temperature (OAT) and system load re-
sult in a condensing pressure above 360 psig, the output
signal is 0 volts. At a signal voltage of 0, the damper
actuator motor drives the damper 100% open.
At refrigerant pressures below 260 psig, the control
output signal is 10 VDC, driving the damper actuator
100% closed.
In practical operation, the condenser intake damper is
fully closed whenever sensed refrigerant pressure is
below 260 psig. This normally occurs during an ex-
tended system OFF interval, especially during periods
of moderate to low OA temperatures. Upon compres-
sor start, the pressure in the system increases until it
reaches the 260 psig minimum throttling range. The
damper only begins to modulate at pressures above
260 psig, ensuring that the actual operating condensing
pressure is always greater than this minimum value.
(C450CPN-4)
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