13
Install Sensors
SPACE TEMPERATURE SENSOR INSTALLATION —
A space temperature sensor must be installed for each fan coil
controller. There are four types of SPT sensors available from
Carrier: the 33ZCT55SPT space temperature sensor with timed
override button, the 33ZCT56SPT space temperature sensor
with timed override button and set point adjustment, the
33ZCT57SPT space temperature sensor with timed override
button, set point adjustment, and manual fan speed control and
the 33ZCT58SPT space temperature sensor with time override,
set point adjustment, fan speed control, and LCD display. See
Fig. 14 and 15.
The space temperature sensor is used to measure the build-
ing interior temperature and should be located on an interior
building wall. The sensor wall plate accommodates the NEMA
standard 2 x 4 junction box. The sensor can be mounted direct-
ly on the wall surface if acceptable by local codes.
Do not mount the sensor in drafty locations such as near air
conditioning or heating ducts, over heat sources such as base-
board heaters, radiators, or directly above wall mounted light-
ing dimmers. Do not mount the sensor near a window which
may be opened, near a wall corner, or a door. Sensors mounted
in these areas will have inaccurate and erratic sensor readings.
The sensor should be mounted approximately 5 ft from the
floor, in an area representing the average temperature in the
space. Allow at least 4 ft between the sensor and any corner
and mount the sensor at least 2 ft from an open doorway.
Install the sensor as follows (see Fig. 15):
1. Locate the two Allen type screws at the bottom of the
sensor.
2. Turn the two screws clockwise to release the cover
from the sensor wall mounting plate.
3. Lift the cover from the bottom and then release it from
the top fasteners.
4. Feed the wires from the electrical box through the
opening in the center of the sensor mounting plate.
5. Using two no. 6-32 x 1 mounting screws (provided
with the sensor), secure the sensor to the electrical box.
NOTE: Sensor may also be mounted directly on the
wall using 2 plastic anchors and 2 sheet metal screws
(field-supplied).
6. Use 20 gage wire to connect the sensor to the control-
ler. The wire is suitable for distances of up to 500 ft.
Use a three-conductor shielded cable for the sensor
and set point adjustment connections. The standard
CCN communication cable may be used. If the set
point adjustment (slidebar) is not required, then an
unshielded, 18 or 20 gage, two-conductor, twisted pair
cable may be used.
The CCN network service jack requires a separate,
shielded CCN communication cable. Always use sepa-
rate cables for CCN communication and sensor wir-
ing. (Refer to Fig. 16-18 for wire terminations.)
7. Replace the cover by inserting the cover at the top of
the mounting plate first, then swing the cover down
over the lower portion. Rotate the two Allen head
screws counterclockwise until the cover is secured to
the mounting plate and locked in position.
8. For more sensor information, see Table 1 for ther-
mistor resistance vs temperature values.
NOTE: Clean sensor with damp cloth only. Do not use
solvents.
Wiring the Space Temperature Sensor — To wire the sensor,
perform the following (see Fig. 16-18):
1. Identify which cable is for the sensor wiring.
2. Strip back the jacket from the cables for at least
3-inches. Strip
1
/
4
-in. of insulation from each conduc-
tor. Cut the shield and drain wire from the sensor end
of the cable.
3. Connect the sensor cable as follows:
a. Connect one wire from the cable (RED) to the
SPT terminal on the controller. Connect the other
end of the wire to the left terminal on the SEN ter-
minal block of the sensor.
VALVE/DX1 (OPEN)
GROUND
VALVE/DX2 (CLOSE)
HEAT CLOSE/
STAGE 2
COMMON (24VAC)
HEAT OPEN/
STAGE 1
1
2
3
4
5
6
J5
Baseboard Outputs (J5)
NOTES:
1. (A) Terminals 1 and 3 provide switched 24 VAC output power to the
load.
2. (B) J5-5 must be jumpered to 24 VAC + (J1-1).
CHANNEL J5 Pins (+,–)
DESCRIPTION
CONTROL DEVICE
Valve DX1
(A) 1, 2
Open
24 VAC, 1A
Valve DX2
(A) 3, 2
Close
24 VAC, 1A
HEAT_ST1
(B) 5, 4
Heat Open, 1st Stage
24 VAC, 1A
HEAT_ST2
(B) 5, 6
Heat Close, 2nd Stage
24 VAC, 1A
Fig. 13 — Fan Coil Controller Baseboard Outputs
1001
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