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The RTU Open controller requires the use of a Bryant space
sensor. A standard thermostat cannot be used with the RTU
Open system.
SUPPLY AIR TEMPERATURE (SAT) SENSOR — On
FIOP-equipped 581J unit, the unit is supplied with a supply-air
temperature (SAT) sensor (33ZCSENSAT). This sensor is a tu-
bular probe type, approx 6-inches (152 mm) in length. It is a
nominal 10k ohm thermistor.
The SAT is factory-wired. The SAT probe is wire-tied to the
supply-air opening (on the horizontal opening end) in its ship-
ping position. Remove the sensor for installation. Re-position
the sensor in the flange of the supply-air opening or in the sup-
ply air duct (as required by local codes). Drill or punch a
1
/
-in. hole in the flange or duct. Use two field-supplied, self-
2
drilling screws to secure the sensor probe in a horizontal orien-
tation. See Fig. 45.
SUPPLY AIR
TEMPERATURE
SENSOR
SUPPLY AIR
Fig. 45 — Typical Mounting Location for Supply Air
Temperature (SAT) Sensor on Small Rooftop Units
OUTDOOR AIR TEMPERATURE (OAT) SENSOR —
The OAT is factory-mounted in the EconoMi$er
accessory). It is a nominal 10k ohm thermistor attached to an
eyelet mounting ring.
ECONOMI$ER 2 — The RTU Open controller is used with
EconoMi$er 2 (factory-installed option or field-installed acces-
sory) for outdoor air management. The damper position is con-
trolled directly by the RTU Open controller; EconoMi$er 2 has
no internal logic device.
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. 31. 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 (T55, T56, and T59) and Rnet com-
municating (SPS, SPPL, SPP, and SPPF) sensors. Each type
ROOF
CURB
RETURN AIR
®
2 (FIOP or
40
has a variety of options consisting of: timed override button, set
point adjustment, a LCD screen, and communication tie in.
Space temperature can be also be written to from a building
network or zoning system. However, it is still recommended
that return air duct sensor be installed to allow stand-alone op-
eration for back-up. Refer to the configuration section for de-
tails on controller configurations associated with space sensors.
• 33ZCT55SPT, space temperature sensor with override
button (T-55)
• 33ZCT56SPT, space temperature sensor with override
button and setpoint adjustment (T-56)
• 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. 46 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. 47.
1
2
3
4
5
WHT(GND)
SEN
SW1
BRN (GND)
BLU (SPT)
Fig. 46 — T-55 Space Temperature Sensor Wiring
SEN
SEN
Fig. 47 — RTU Open Controller T-55 Sensor
Connections
Connect T-56
See Fig. 50 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. 49.
—
—
6
RED(+)
CCN COM
BLK(-)
SENSOR WIRING
J20-1
J20-2
1,
—
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