132
THERMISTORS AND PRESSURE TRANSDUCERS
The 48/50A2,A3,A4,A5 units are equipped with four pressure
transducers. These units have two pressure transducers con-
nected to the low side of the system and two pressure transduc-
ers connected to the high side of the system.
By using either temperature sensors or transducers, the Com-
fortLink controller displays the high and low side pressures and
saturation temperatures. A normal gage set is not required.
SMOKE DETECTOR
The units can be equipped with an optional smoke detector lo-
cated in the return air. The detector is wired to the ComfortLink
controls and, if activated, will stop the unit by means of a special
fire mode. The smoke detector can also be wired to an external
alarm system through TB5 terminals 10 and 11. The sensor is lo-
cated in the return air section behind the filter access door.
FILTER STATUS SWITCH
The units can be equipped with an optional filter status switch.
The switch measures the pressure drop across the filters and
closes when an adjustable pressure setpoint is exceeded. The
sensor is located in the return air section behind the filter ac-
cess door.
RETURN AIR CO
2
SENSOR
The unit can also be equipped with a return air IAQ CO
2
sensor
that is used for the demand controlled ventilation. The sensor is
located in the return air section and can be accessed from the
filter access door.
BOARD ADDRESSES
Each board in the system has an address. The MBB has a de-
fault address of 1 but it does have an instance jumper that
should be set to 1 as shown in Fig. 30. For the other boards in
the system there is a 4-dip switch header on each board that
should be set as shown below.
0 = On; 1 = Off
FIELD CONNECTION TERMINAL STRIPS
Field connection terminal strips are located in the main control
box. See Fig. 37 and Table 109.
BOARD SW1 SW2 SW3 SW4
ECB10000
ECB21000
SCB0000
CEM0000
Fig. 37 — Field Connection Terminal Strips (Main Control Box)
13579111315
246810121416
12345678
R Y1Y2W1W2G C X
13579111315
246810121416
TB5
TB6
TB3
TB4
C
LEN
CCN
CCN
+
-
GRD
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