Service Manual -
B-VMHxxAV-1
10. Engineering of Electrical Wring
NOTE: The wiring method of the thermostat and
the internal machine refers to the wiring of the non-
communication scheme.
3. Optional function wiring
3.1 Condensate overflow switch
The unit will accommodate a remote condensate overflow
switch. To enable, remote jumper J1, and connect the
installer provided condensate overflow device to CN5 per
below. When an overflow condition is present, the device
should open connection signaling the unit to turn off the
system.
3.2 The fault warning
Alarm output:
An alarm output(CN33) can be utilized if actions are
required when a fault is present. This is a passive outlet
port, so you will need to input a voltage signal. The relay
is normally-open for normal operation, and closed when a
fault condition is active.
CN23
ALARM
3.3 Humidification control wiring
• To connect a humidifier, utilize the passive signal
“WORK” output (CN23) port as well as the G and C
wires on the controller, and wire the humidistat and
humidifier per above wiring diagram. When the fan
is running, the CN23 relay will be closed, which will
allow power to the humidifier when the humidistat
is below humidity setpoint. If the thermostat or
zone controller has an HUM interface, connect the
humidifier directly to the HUM and C ports.
TO
HUMIDIFIER
WORK
HUMIDISTAT
24V control signal or 208/230V power supply
CN33
TO HUMIDIFIER
HUMIDISTAT
24-VAC
G
C
3.4 Dehumidification control wiring
1 2
ON
S4
DH
R
HUMIDISTAT
Dehumidification control requires indirect humidifier
at DH and R. Set S4-2 as OFF. When the humidity rises
and exceeds the set value of the humidifier, the 24V
signal of DH changes to 0V, the cooling system starts the
dehumidification operation, and the air volume drops to
80% of the nominal cooling air volume.
When the partition control, DH is connected to the DH
port of the partition controller. When the 24V signal of
DH changes to 0V, the air volume drops to 80% of the
nominal refrigeration air volume.
3.5 UV, fresh air or negative ion wiring
The WORK port is linked with the fan. When the fan
is running, the relay is closed; if an active 24V signal is
required, it can be directly connected to the G and C ports.
work
24V control signal or 208/230V power supply
UV, fresh wind or
negative ions, etc
CN33
4. Control Logic
Indoor unit Connector
Connector
Purpose
R
24V Power Connection
C
Common
G
Fan Control
Y1
Low Cooling
Y/Y2
High Cooling
B
Heating Reversing Valve
W
Heating Control
W1
Stage 1 Electric heating
W2
Stage 2 Electric heating
E/AUX
Emergency heating
DH/DS/BK
Dehumidification/Zoning
control
L
System Fault Signal
Summary of Contents for Comfort-Aire Century A-VMH18SV-1
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Page 38: ...Service Manual B VMHxxAV 1 Outdoor Unit 4 4 Panel Plate D30 Square grille ...
Page 39: ...Service Manual B VMHxxAV 1 Outdoor Unit 5 5 2 Service Place Minimim 4 Recommended 12 ...
Page 42: ...Service Manual B VMHxxAV 1 Outdoor Unit 8 8 A VMH18SV 1 A VMH24SV 1 ...
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