Operation, Settings and adjustment, W7345 – Honeywell W7340 User Manual

Page 7

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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

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