Installation and Maintenance Manual

Controls
84 SCXG-SVX01H-EN
Supply Air Temperature Sensor
The supply air temperature sensor is an analog input
device. It monitors the supply air temperature for supply
air temperature control, supply air temperature reset,
supply air temperature low limiting, and supply air
tempering. It is mounted in the supply air discharge
section of the unit and connected to the RTM.
Supply Airflow Proving Switches
This is binary input device used on units to signal the RTM
when the supply fan is operating. It is mounted in the
supply fan section and is connected to the RTM. During a
request for fan operation and if the differential switch
opens for 40 consecutive seconds, compressor operation
turns off, heat operation turns off, the request for supply
fan operation is turns off and locks out, economizer
damper option closes, and a manual reset diagnostic
initiates.
Low Entering Air Protection Device (LEATPD)
The low entering air protection device (LEATPD) is a binary
input on units with hydronic heat or a waterside
economizer. It is optional on water-cooled units.
If the LEATPD is on a unit with factory-installed heat, it is
mounted in the heat section and connected to the heat
module. If the entering air temperature to the heating coil
falls to 40°F, the normally open contacts on the LEATPD
close and cause the following events:
a. the hydronic heat actuator fully opens.
b. the supply fan turns off
c. the outside air damper closes
d. the SERVICE light at the remote zone sensor option
turns on.
e. a LEATPD diagnostic displays at the human
interface panel.
If the LEATPD is on a water-cooled unit without factory-
installed heat, it is wired to the WSM. It will trip if the
entering water temperature falls to 34°F, open the
economizer valve, and energize the pump output.
High Duct Temp Thermostat Option On Units
with an LCI-I
The high duct temperature thermostats are binary input
devices used on units with aTrane communication
interface module (Tracer/LCI-I).They provide a high limit
unit shutdown and require a manual reset.The
thermostats are factory set to open if the supply air
temperature reaches 240°F, or the return air temperature
reaches 135°F. Once tripped, the thermostat requires a
manual reset. Reset by pressing the sensor’s reset button
when the air temperature decreases approximately 25°F
below the cutout point.
Filter Switch
The filter switch is a binary input device that measures the
pressure differential across the unit filters. It is mounted in
the filter section and connected to the RTM. A diagnostic
SERVICE signal displays at the remote panel if the
pressure differential across the filters is at least 0.5” w.c.
The contacts automatically open when the pressure
differential across the filters decrease to 0.4” w.c.The
switch differential is field adjustable between 0.17” to 5.0”
w.c. ± 0.05 “.
High Duct Static Switch Option
The high duct static switch is field-mounted in the
ductwork or plenums with smoke dampers. It will cause a
manual reset diagnostic if the duct static exceeds the pre-
set static limit.The static limit is adjustable at the HI.