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SUPPLY AIR
TEMPERATURE
SENSOR
SUPPLY AIR
Fig. 73 — Typical Mounting Location for Supply Air
Temperature (SAT) Sensor on Small Rooftop Units
Outdoor air management functions can be enhanced with
field-installation of these accessory control devices:
Enthalpy control (outdoor air or differential sensors)
Space CO
sensor
2
Outdoor air CO
sensor
2
Field Connections —
Field connections for accessory sen-
sors and input devices are made the RTU Open controller, at
plugs J1, J2, J4, J5, J11 and J20. All field control wiring that
connects to the RTU Open controller must be routed through
the raceway built into the corner post as shown in Fig. 36. The
raceway provides the UL required clearance between high and
low-voltage wiring. Pass the control wires through the hole
provided in the corner post, then feed the wires through the
raceway to the RTU Open controller. Connect to the wires to
the removable Phoenix connectors and then reconnect the con-
nectors to the board.
SPACE TEMPERATURE (SPT) SENSORS — There
are two types of SPT sensors available from Bryant, resistive
input non-communicating (T-55, T-56, and T-59) and Rnet
communicating (SPS, SPPL, SPP, and SPPF) sensors. Each
type has a variety of options consisting of: timed override but-
ton, set point adjustment, a LCD screen, and communication
tie in. Space temperature can be also be written to from a build-
ing network or zoning system. However, it is still recommend-
ed that return air duct sensor be installed to allow stand-alone
operation for back-up. Refer to the configuration section for
details on controller configurations associated with space sen-
sors.
• 33ZCT55SPT, space temperature sensor with override
button (T-55)
• 33ZCT56SPT, space temperature sensor with override
button and setpoint adjustment (T-56)
ROOF
CURB
RETURN AIR
• 33ZCT59SPT, space temperature sensor with LCD (liq-
uid crystal display) screen, override button, and setpoint
adjustment (T-59)
Use 20 gauge wire to connect the sensor to the controller.
The wire is suitable for distances of up to 500 ft. Use a three-
conductor shielded cable for the sensor and setpoint adjustment
connections. If the setpoint adjustment (slidebar) is not re-
quired, then an unshielded, 18 or 20 gauge, two-conductor,
twisted pair cable may be used.
Connect T-55
See Fig. 74 for typical T-55 internal connec-
—
tions. Connect the T-55 SEN terminals to the RTU Open con-
troller at J20-1 and J20-2. See Fig. 75.
1
2
4
3
SEN
SW1
Fig. 74 — T-55 Space Temperature Sensor Wiring
SEN
SEN
Fig. 75 — RTU Open Controller T-55 Sensor
Connect T-56
See Fig. 76 for T-56 internal connections. In-
—
stall a jumper between SEN and SET terminals as illustrated.
Connect T-56 terminals to the RTU Open controller at J20
J20
2 and J20
3 per Fig. 77.
—
—
55
5
6
RED(+)
WHT(GND)
CCN COM
BLK(-)
BRN (GND)
SENSOR WIRING
BLU (SPT)
J20-1
J20-2
Connections
1,
—
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