52
VCCX2 Controller Technical Guide
Suction Pressure Sensor Wiring
The ASM02222 Suction Pressure Transducer must be wired as
shown in Figure 32, page 51. It is required for all compressorized
VCCX2 applications.
The Suction Pressure Sensor is used to measure suction pressure
at the HVAC unit’s DX evaporator coil suction line. This suction
line pressure is converted to saturated refrigerant temperature by
the RSMV Controller. This temperature is used by the RSMV to
accurately control the Expansion Valves to maintain Superheat
to provide optimum performance of the system. The saturated
refrigerant temperature is used to properly control the compressors
to maintain a given Suction Coil (Saturated) Temperature
Setpoint. In Cooling and Heat Pump mode, the VCCX2 resets
the Suction Coil (Saturated) Temperature Setpoint to maintain
a given supply air temperature setpoint. In Dehumidication
mode, the Suction Coil (Saturated) Temperature Setpoint is a
user congurable setpoint that does not reset.
Head Pressure Control
The RSMV can monitor a Head Pressure Transducer and control
Condenser Fans to maintain a Head Pressure Setpoint. The
Condenser Fan will be controlled with a 0-10 VDC output signal.
Coil Temperature Sensors
The Coil Temperature Sensors are used to measure Coil
Temperature after each evaporator coil line. This temperature
combined with the calculated saturated refrigerant temperature
is used to calculate the Superheat of each individual evaporator
coil. The Superheat is used to drive the Expansion Valves to
maintain a given Superheat Setpoint.
CAUTION: The Shraeder port used for installation of the
suction pressure transducer should be located
in a vertical position of the suction line to
prevent refrigerant oil from accumulating in
the sensor.
18-30 VAC
GND
Line
Voltage
Size ransformer ortf
ctlorrect otal oad.
RSMV = 18 VA
CONDENSER ENABLE
COMPRESSOR 2 ENABLE
COMPRESSOR 1 ENABLE
24 VAC ONLY
RLY1
RLY3
RLY2
COMM
RD
WH
BK
GRN
RD
WH
BK
GRN
EXPANSION
VALVE 1
EXPANSION
VALVE 2
COM
+
MODULATING
COMPRESSOR
COM
+
CONDENSER
FAN SIGNAL
AOUT1
AOUT2
GND
Connect to
VCCX2 Controller
Note:
All relay outputs are normally open
and rated for 24 VAC power only.
1 Amp maximum load.
Figure 33: RSMV Outputs Wiring
WIRING
RSMV Controller Outputs
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