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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 —
sensors 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. 35. 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 Carrier, resistive input
non-communicating (T55, T56, and T59) and Rnet communi-
cating (SPS, SPPL, SPP, and SPPF) sensors. Each type 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. 54 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. 73.
SEN
SEN
Fig. 73 — 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. 74.
—
—
Field connections for accessory
J20-1
J20-2
SEN
SEN
SET
SET
Fig. 74 — RTU Open Controller T-56 Sensor
Connect T-59
isolated power supply of 24 VAC. See Fig. 75 for internal con-
nections at the T-59. Connect the SEN terminal (BLU) to the
RTU Open controller at J20
(BRN) to J20
—
J20
3.
—
OR
SET
OPB
NOTE: Must use a separate isolated transformer.
Fig. 75 — Space Temperature Sensor Typical
INDOOR AIR QUALITY (CO
air quality sensor accessory monitors space carbon dioxide
(CO
) levels. This information is used to monitor IAQ levels.
2
Several types of sensors are available, for wall mounting in the
space or in return duct, with and without LCD display, and in
combination with space temperature sensors. Sensors use infra-
red technology to measure the levels of CO
space air.
The CO
sensors are all factory set for a range of 0 to 2000
2
ppm and a linear mA output of 4 to 20. Refer to the instructions
supplied with the CO
terminal locations. See Fig. 59 for typical CO
1,
—
schematic.
To accurately monitor the quality of the air in the condi-
tioned air space, locate the sensor near a return-air grille (if
present) so it senses the concentration of CO
The sensor should be mounted in a location to avoid direct
breath contact.
55
J20-1
J20-2
Jumper
J20-3
Connections
The T-59 space sensor requires a separate,
—
1. Connect the COM terminal
—
2. Connect the SET terminal (STO or BLK) to
BLK (STO)
J20-3
BRN (COM)
J20-2
BLU (SPT)
J20-1
SEN
COM- PWR+
24 VAC
Wiring (33ZCT59SPT)
) SENSOR — The indoor
2
sensor for electrical requirements and
2
SENSOR
WIRING
POWER
WIRING
present in the
2
sensor wiring
2
leaving the space.
2
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