W7340, W7345 COMMUNICATING ECONOMIZER LOGIC MODULES
7
63-2569—04
Fig. 7. W7345 Typical Wiring.
OPERATION
The purpose of the economizer logic modules are to use
outdoor air for cooling, whenever possible, to reduce
compressor operation.
IMPORTANT
• Use C7400A sensor with W7340A or W7340B.
• Use C7400C with W7340C.
The W7340, when wired as shown in Fig. 6, responds to a
signal from the Modbus. This system uses C7400 Solid State
Enthalpy Changeover Sensor(s). The C7400 Enthalpy Sensors
respond to both dry bulb temperature and humidity, allowing
use of outdoor air at higher temperatures for free cooling when
humidity is low.
The logic module functions as a first stage of cooling and
provides maximum fuel economy during the cooling cycle. The
logic module automatically locks out free cooling during
heating. It holds the outdoor air damper at the minimum
position setting.
The W7340 operates as a basic free cooling controller. Table 2
details the input/output (I/O) logic of the W7340. The logic
module energizes the Unit Control and Indoor Fan contacts,
and operates according to Table 2.
SETTINGS AND ADJUSTMENT
W7345
Potentiometers with screwdriver adjustment slots, located on
the face of the device, provide adjustments for Minimum
Damper Position parameters (See Fig. 8 for locations on
device).
Fig. 8. Location of W7345 Potentiometers and LED.
P1
TR1
TR1
24 VAC
TR
TR
P
MOD BUS –
MOD BUS +
M23876
PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
OPTIONAL REMOTE MINIMUM POSITION POTENTIOMETER.
1
1
2
2
R
B
W
–
24 VAC
L1
L2
+
CCW
OPEN
MOD
BUS
CW
CLOSE
S963B
M7215
W7345
MINIMUM
POSITION
MIXED
AIR TEMP
SENSOR
10K NTC
MA
T
+
–
A
E
B
C
D
P P1
MBUS-
MBUS+
TR1 24V COM
TR 24V AC
-
MIN POS/
DVC MIN
OPEN
C
B
E
A
STATUS LED
DRY BULB
CHANGEOVER
SETPOINT
MINIMUM
DAMPER
POSITION
M23877
D
MAT
OAT
RAT
