Lennox SCH120 User Manual

Page 16
507964-01 9/2019
FIGURE 16
FIELD WIRING WITH ELECTRONIC AND ELECTRO-MECHANICAL THERMOSTATS
(Thermostat Mode)
J262C
10
11
12
P297
J297A
1
2
B
3
4
5
6
7
8
C
9
10
24 V POWER
W1
W2
P262
A55
R
OCP
C
G
W1
W2
Y1
Y2
2
K55
B
A
K55−1
7
5
2
S86
R
OCP
C
G
W1
W2
Y1
Y2
TO R
TO G
TO Y1
TO PROVIDE SUPERMARKET REHEAT SCHEME
USE S86 DEHUMIDISTAT AND K55.
ALL OTHER THERMOSTAT
SIGNALS REMAIN CONNECTED
AS SHOWN ON THE RIGHT.
TO UNIT CONTROLLER
2
THERMOSTAT INPUTS
FIGURE 17
FIELD WIRING IN ZONE SENSOR MODE
(Zone Sensor Mode)
A2 SENSOR
OUTPUTS
SENSOR
SENSOR
24VAC
R C
IAQ
HUM
AI1
D01
TMP
D02
UNIT CONTROLLER
J298
C-Hot Gas Reheat or Ultra High Efficiency Units Only -
1- Install humidity sensor in accordance with instructions
provided with sensor. A DDC input may be used to
initiate dehumidification instead of a sensor.
2- Make wiring connections as shown in figure 16 for
Thermostat Mode or figure 17 for Zone Sensor
Mode. In addition, connect either a humidity sensor
or a dehumidification input. See figure 18 or 19 for
humidity sensor wiring or figure 20 for
dehumidification input wiring.
Humidity Sensor Cable Applications:
Wire runs of 50 feet (mm) or less:
Use two separate shielded cables containing 20AWG
minimum, twisted pair conductors with overall shield.
Belden type 8762 or 88760 (plenum) or equivalent.
Connect both cable shield drain wires to the Unit Controller
as shown in figure 18.
Wire runs of 150 feet (mm) or less:
Use two separate shielded cables containing 18AWG
minimum, twisted pair conductors with overall shield.
Belden type 8760 or 88760 (plenum) or equivalent.
Connect both cable shield drain wires to the Unit Controller
as shown in figure 18.
FIGURE 18
FIELD WIRING REHEAT UNITS (Using A Humidity
Sensor With Less Than 150 Ft. Wire Runs)
9
8
10
11
12
J262B
5
P298J298A
1
2
B
3
4
C
5
6
7
D
A91
VIN
VO
GND
P262
R
C
AI−1
HUM
TMP
DO−1
C

Lennox SCH120 Specifications

General

Brand	Lennox
Model	SCH120
Category	Air Conditioner
Language	English