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W7081
LIMIT CONTROLLER
ECONOMIZER/MIXED AIR LOW LIMIT–A5
1
2
3
COLD DECK LOW LIMIT–A6
1
2
3
HOT DECK HIGH LIMIT–A7
1
2
3
(OR C7100B)
REMOTE
RETURN
AIR SENSOR
(IF USED)
1
C7100B AVERAGING
TEMPERATURE SENSOR
MAY BE SUBSTITUTED IF
SPACE PERMITS.
2
REMOTE RETURN AIR
SENSOR USED WITH T7080B ONLY.
Fig. 5. Connecting C7046B Air Temperature Sensor
for mixed air, cold deck and hot deck sensing, zone
discharge and optional remote return air sensing
in W7080 Multizone System.
C7046D
1
1
2
2
Fig. 6. Connecting C7046D Air Temperature
Sensor to Excel 500 Control System.
4
5
6
(OR C7100B)
50
55
60 NO JUMPER
4
5
6
(OR C7100B)
COLD DECK
45
55
55 NO JUMPER
4
5
6
(OR C7100B)
90
110
130 NO JUMPER
24 Vdc
7
8
–
+
+24 VDC
C7046B
C7046B
T7080A,B
(OR C7100B)
ZONE (N)
DISCHARGE
7
1
SENSOR
6
2
5
3
4
8
2
XF521A/XF526
1
AI 1
2
3
AI 2
4
5
AI 3
6
7
8
AI 4
9
10
AI 5
11
12
AI 6
13
14
AI 7
15
16
AI 8
17
18
M2825
C7046A,B,C,D AIR TEMPERATURE SENSORS
OPERATION AND CHECKOUT
Operation
The C7046A,B,C Air Temperature Sensors consist of a
thermistor sensing element mounted in a tubular probe.
C7046B
They are applied at various locations throughout single
MIXED AIR
zone and multizone duct systems. The negative
SENSOR
temperature coefficient (NTC) characteristic of the
thermistor element causes its resistance to decrease as
the sampled air temperature increases. This resistance
C7046B
shift is balanced with other system sensor signals by
appropriate system logic panels to stabilize system
SENSOR
control.
The C7046D Air Temperature Sensor consists of a
C7046B
platinum thin film sensor element mounted in a tubular
HOT DECK
probe. It can be applied at various locations throughout
SENSOR
single zone and multizone duct systems. The positive
temperature coefficient (PTC) characteristics of the
platinum thin film element causes its resistance to
increase as the sampled air temperature increases. This
resistance shift is balanced with other system sensor
signals by the Excel 500 Control System.
Checkout
Allow the C7046 Air Temperature Sensor to soak in the
air moving through the duct or plenum for a minimum of
five minutes before taking a resistance measurement.
1. Disconnect the sensor leadwires from the associ-
ated system components.
2. Connect an ohmmeter across the leadwires.
3. Assure nominal resistance measurements are in
M17966A
accordance with the resistance/temperature curves
shown in Figs. 7, 8 and 9.
4. Reconnect sensor leadwires to associated system
components.
5. Check operation of the complete control system.
17000
16000
15000
14000
13000
12000
11000
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
10
Fig. 7. C7046A,C Sensor resistance vs. temperature.
3
20
30
40
50
60
-10
-5
0
5
10
15
TEMPERATURE (DEGREES)
3,000 OHMS
AT 77 F (25 C)
70
80
90
100
F
20
25
30
35
C
M17969
62-0216
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