Lennox LHT Series Service Manual page 35

N-Drain Pan Overflow Switch S149 (optional)
The overflow switch is used to interrupt cooling operation
when excessive condensate collects in the drain pan. The
N.C. overflow switch is connected to the M2 Unit Control-
ler (A55) through DI-3. When the switch opens, the Unit
Controller will shut off the unit. After a five-minute time out,
the Unit Controller will verify the overflow switch position
and restart the unit (if the switch has closed). The Unit
Controller has a three-strike counter before the unit locks
out. This means the Unit Controller will allow the overflow
switch to open three times per thermostat demand. If the
unit locks out, a reset of the Unit Controller is required af-
ter the switch has closed to restore unit operation.
O-Indoor Air Quality Sensor
If a sensor fails, use the following procedures to physically
remove the failed sensor from the unit. All units will have
two IAQ sensors installed, one in the return air and the
second one in the supply side. See figure 23. The sensors
are secured to the tray by two screws. The power cable
assembly will need to be detached from the connector lo-
cated on the bottom of the sensor as well.
Removing the Sensor
1 - Go to Menu > Network Integrations > Wireless
Sensor Network Setup > Wireless Sensor Network.
2 - From the Network Nodes list, select the IAQ sensor
that is being replaced.
3 - On the Sensor Information Screen, select the
Remove Sensor option at the bottom of the screen.
4 - Type in the sensor name that is to be removed and
select Proceed.
Replacing the Sensor
1 - Open the CORE Service App and navigate to Menu
> (Setup) Network Integration > Wireless Sensor
Network Setup > Wireless Sensor Network.
2 - Click Add node on the Network Nodes screen. This
triggers the CORE Service App to scan for both the
WIAQ Return Sensor and WIAQ Discharge Sensor.
3 - Follow the prompts on the screen to finish the
adding process.
4 - Verify that the CORE Service App displays the "Node
Provisioned" on the Provision Sensor Network.
5 - Verify if CORE Service app is showing PM2.5
counts for both return and supply mounted sensors
and TVOC counts from return mounted sensor.
P-Bipolar Ionizer
The Needlepoint Bipolar Ionizer (NBPI) kit is specifically
designed for LG/LC/LH/LD/KG/KC/KH 024-300 units. The
ionizer is equipped with dry contacts which allow a Build-
ing Automation System (BAS) to interface and indicate
ionizer functionality.
Note - The BAS will be able to monitor units equipped with
M4 Unit Controllers only. Units with an M3 Unit Controller
or no controller need to be connected to a separate mon-
itoring system.
The Ionizers are also equipped with a green LED which
indicates power is on. When the blower is in operation,
power is delivered to the Ionizers and ions are generated.
See table 10 for unit application.
LHT Unit
156
240
300
Page 35
Location of both
the Supply and Return
IAQ Sensors
Always install IAQ
Sensor so Status Indicator
is viewable.
FIGURE 23
TABLE 10
Part No.
21U37 622688-03
21U38 622688-04
21U39 622688-05