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Timed Discrete Output —
available for switching on and off items such as parking lot
lights. Time Schedule II (
operates this function. A special relay (part no. HK35AB001)
with a 20 vdc holding coil must be field wired. See Fig. 23.
Air Pressure Tubing —
guide vanes (IGV), variable frequency drive (VFD), and/or
modulating power exhaust can operate properly, the pneumatic
tubing for pressure sensing must be installed. Use fire-retardant
plenum tubing (field-supplied). Tubing size is
plications. Tubing must be run from the appropriate sensing lo-
cation (in the duct or in the building space) to the control de-
vice location in the unit.
INLET GUIDE VANES — The tubing for the duct pressure
(DP) control option should sample supply duct pressure about
2/3 of the way out from the unit in the main trunk duct, at a
location where a constant duct pressure is desired.
The duct pressure is sensed by a pressure transducer. The
output of the pressure transducer is directed to the unit control
module. On all sizes, the DP transducer is located in the unit
auxiliary control box. See Fig. 30 and 31. Use a nominal
plastic tubing. Control box details are shown in Fig. 32 and 33.
VARIABLE FREQUENCY DRIVE — The tubing for the
duct pressure (DP) control option should sample supply duct
pressure about 2/3 of the way out from the unit in the
main trunk duct, at a location where a constant duct pressure is
desired.
The duct pressure is sensed by a pressure transducer. The
pressure transducer output is directed to the unit control mod-
ule. On all sizes the DP transducer is located in the unit auxilia-
ry control box. See Fig. 30 and 31. Use a nominal
tubing. Control box details are shown in Fig. 32 and 33.
MODULATING POWER EXHAUST — The tubing for the
building pressure control (achieved via the Modulating Power
Exhaust option) should sample building pressure in the area
near the entrance lobby (or other appropriate and sensitive lo-
cation) so that location is controlled as closely to design pres-
sures as possible.
These units use a pressure transducer for sensing building
pressure. The BP transducer is located in the unit auxiliary con-
trol box. See Fig. 30 and 31. Use a nominal
ing. Control box details are shown in Fig. 32 and 33.
Space Temperature Sensors
STANDARD
SPACE
(T-55) — The T-55 (part no. CEC0121448-01) sensor is a
wall-mounted device used to measure space temperature and
for unoccupied heating and cooling operation. It should be in-
stalled as a wall-mounted thermostat would be (in the condi-
tioned space where it will not be subjected to either a cooling or
heating source or direct exposure to sunlight, and 4 to 5 ft
above the floor). It can also be used to override the occupancy
schedule in the unit by pushing the button on the front. Refer to
Space Temperature Sensor (T-55) section on page 34 for wir-
ing details.
ACCESSORY
SPACE
(T-56) — The T-56 sensor (part no. CEC0121503-01) oper-
ates the same as the standard T-55 sensor but has an additional
feature of allowing the user to change the set point ± 5º F. The
T-56 sensor is applicable to CV applications only. A slide po-
tentiometer is used to provide the space temperature offset and
is located on the face of the device. The sensor is a wall-mount-
ed device and should be installed as a wall-mounted thermostat
would be (in the conditioned space where it will not be subject-
ed to either a cooling or heating source or direct exposure to
sunlight, and 4 to 5 ft above the floor). It can also be used to
A timed discrete output is
SCHD to
SCHD)
Before options such as inlet
1
/
in. for all ap-
4
1
/
1
/
-in. plastic
4
1
/
-in. plastic tub-
4
TEMPERATURE
SENSOR
TEMPERATURE
SENSOR
Fig. 30 — Auxiliary Control Box Location;
-in.
4
override the occupancy schedule in the unit by pushing the but-
ton on the front.
SPACE TEMPERATURE AVERAGING — Applications
that require averaging using multiple space temperature sen-
sors can be satisfied using either 4 or 9 T-55 sensors as shown
in Fig. 15. Single space temperature reset wiring is discussed in
detail in Space Temperature Sensor sections on page 34.
NOTE: Only Carrier T-55 sensors may be used for standard
T-55 space temperature averaging. Sensors must be used in
multiples of 1, 4 and 9 only, with total sensor wiring not to
exceed 1000 ft.
NOTE: Do not use T-56 sensor for space temperature averag-
ing because 5º F offset function will not work in a multiple
sensor application.
NOTE: When the T-55 sensor is wired in a 4- or 9-sensor
application, the unoccupied schedule Timed Override function
button on the sensor will no longer operate.
Humidity Sensors
RELATIVE
Mounted) — The accessory field-installed, wall-mounted type
RH sensor (part no. HL39ZZ001) measures the relative humid-
ity of the air within the occupied space. Use a junction box to
accommodate the wiring when sensor is mounted in the occu-
pied space. Sensor must be mounted with terminals ACIN and
OUT + located at the top of the sensor. Supply 24 vac to this
sensor from an isolated power supply. The control options
module (available as a factory-installed option or field-installed
accessory on size 034-074 units and is standard on 078-104
units) is required for operation.
RELATIVE
Mounted) — The accessory field-installed, duct-mounted RH
sensor (part no. HL39ZZ002) can be installed either in the
return-air ductwork or the outdoor-air ductwork. If 2 relative
humidity sensors are ordered for differential enthalpy control,
then the sensors will be installed in the conditioned space (CV
applications) or the return air (VAV applications) and outdoor
airstream. If the sensor is to be used for control of a humidifier,
install the sensor in the return-air duct. Supply 24 vac to this
sensor from an isolated power supply. The control options
module (available as a factory-installed option or field-installed
accessory on size 034-074 units and is standard on 078-
104 units) is required for operation.
41
Size 034-048 Units
HUMIDITY
(RH)
SENSOR
HUMIDITY
(RH)
SENSOR
(Wall
(Duct
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