Blower Operation And Adjustments - Lennox LGT156H Installation Instructions Manual

D-Hot Gas Reheat 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 9 for
Thermostat Mode and figure 10 for Zone Sensor
Mode. In addition, connect either a humidity sensor
or a dehumidification input. See figure 11 or 12 for
humidity sensor
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 TB1-7 as shown
in figure 11.
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 TB1-7 as shown
in figure 11.
Wire runs over 150 feet (mm):
Use a local, isolated 24VAC transformer such as Lennox
cat #18M13 (20VA minimum) to supply power to RH
sensor as shown in figure 12. Use two shielded cables
containing 20AWG minimum, twisted pair conductors
with overall shield. Belden type 8762 or 88760 (plenum)
or equivalent.
FIELD WIRING REHEAT UNITS (Using A Humidity
Sensor With Less Than 150 Ft. Wire Runs)
NOT
CONNECTED
A91
VIN
GND
DRAIN
VO
NOT
CONNECTED
FIGURE 11
wiring and figure 13
A55 UNIT
CONTROLLER
P298
J298
1
2
3
4
5
6
7
8
9
10
UNUSED
WIRE
FIELD WIRING REHEAT UNITS (Using A Humid­
ity Sensor With More than 150 Ft. Wire Runs)
NOT
CONNECTED
A91
for
VIN
GND
VO
(Using A Dehumidification Switch)
DEHUMIDIFICATION
SWITCH

Blower Operation and Adjustments

R
Supply Air Staged Units - The blower rotation will
C
always be correct on units equipped with an inverter.
AI-1
Checking blower rotation is not a valid method of
determining voltage phasing for incoming power.
HUM
Supply Air Staged Units and Units Equipped With
Optional Voltage or Phase Detection - The Unit
TMP
Controller checks the incoming power during start-up. If
the voltage or phase is incorrect, the Unit Controller will
AI2
display an alarm and the unit will not start.
C
A-Blower Operation
R
Refer to the Unit Controller Setup Guide to energize
blower. Use this mobile service app menu:
SERVICE > TEST > BLOWER
Page 13
ISOLATED 24V
TRANSFORMER
P298
1
DRAIN
2
NOT
3
CONNECTED
4
5
6
7
8
9
10
FIGURE 12
FIELD WIRING REHEAT UNITS
P299
7
8
9
10
Use 24 VAC (R) from any terminal
available on P299−2, −5, or −7.
FIGURE 13
A55 UNIT
CONTROLLER
J298
R
C
AI-1
HUM
TMP
AI2
C
R
R
DI−4
C
508288-01 9/2022