Honeywell C7046A - Manual (Page 3)

C7046A,B,C,D AIR TEMPERATURE SENSORS
3 62-0216
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.
Fig. 6. Connecting C7046D Air Temperature
Sensor to Excel 500 Control System.
OPERATION AND CHECKOUT
Operation
The C7046A,B,C Air Temperature Sensors consist of a
thermistor sensing element mounted in a tubular probe.
They are applied at various locations throughout single
zone and multizone duct systems. The negative
temperature coefficient (NTC) characteristic of the
thermistor element causes its resistance to decrease as
the sampled air temperature increases. This resistance
shift is balanced with other system sensor signals by
appropriate system logic panels to stabilize system
control.
The C7046D Air Temperature Sensor consists of a
platinum thin film sensor element mounted in a tubular
probe. It can be applied at various locations throughout
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
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.
Fig. 7. C7046A,C Sensor resistance vs. temperature.
M17966A
C7046B
(OR C7100B)
MIXED AIR
SENSOR
C7046B
(OR C7100B)
COLD DECK
SENSOR
C7046B
(OR C7100B)
HOT DECK
SENSOR
2 1
HOT DECK HIGH LIMIT–A7
3 4 5 6
90
110
130 NO JUMPER
7 8
24 Vdc
W7081
LIMIT CONTROLLER
2 1
COLD DECK LOW LIMIT–A6
3 4 5 6
45
55
55 NO JUMPER
2 1
ECONOMIZER/MIXED AIR LOW LIMIT–A5
3 4 5 6
50
55
60 NO JUMPER
+24 VDC
– +
T7080A,B C7046B
(OR C7100B)
ZONE (N)
DISCHARGE
SENSOR
2
3
1
8
6
5
7
4
C7046B
(OR C7100B)
REMOTE
RETURN
AIR SENSOR
(IF USED)
1
2
C7100B AVERAGING
TEMPERATURE SENSOR
MAY BE SUBSTITUTED IF
SPACE PERMITS.
REMOTE RETURN AIR
SENSOR USED WITH T7080B ONLY.
2
18
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
AI 1
AI 2
AI 3
AI 4
AI 5
AI 6
AI 7
AI 8
1
2
1
2
C7046D XF521A/XF526
M2825
4000
3000
2000
1000
8000
7000
6000
5000
12000
11000
10000
9000
16000
17000
15000
14000
13000
60 50 40 70 80 10 20 30 90 100
15 20 10 25 -5 0 -10 5 30 35
RESISTANCE (OHMS)
TEMPERATURE (DEGREES)
M17969
F
C
3,000 OHMS
AT 77 F (25 C)