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VisionPRO
TM
8000 Touchscreen Programmable Thermostat
68-0280—01 36
C7089U Outdoor Temperature Sensor
Operation
When installed with Thermostat Installer Setup Number 0340
set to 1 or 2, the outside temperature can be displayed on the
thermostat. See Fig. 35.
Fig. 35. Outside temperature reading on
TH8000 Series Thermostat.
The C7089 Outdoor Sensor converts outdoor ambient
temperature to a resistance that the thermostat can interpret.
The C7089 has a negative temperature coefficient (TC), which
means that resistance decreases as the temperature
increases. See Table 12.
Checkout
Allow C7089U Outdoor Sensor to absorb outdoor air for a
minimum of twenty minutes before taking a reading.
With an accurate thermometer (±1°F [0.5°C]) measure the
temperature at the sensor location, allowing time for the
thermometer to stabilize before reading.
To verify sensor resistance, remove one wire from one of the
C7089 60-in. leadwires. Use an ohmmeter to measure the
resistance across the sensor. Then verify the sensor accuracy
with the temperature/resistance in Table 12.
Calibration
The C7089 Outdoor Sensor is calibrated at the factory and
cannot be recalibrated in the field.
SCHED HOLD CLOCK SCREEN MORE
MON
T
UE
WED
THU
FRI
SA
T
A
A
T
SUN
AM
FAN
A
U
T
O
SYSTEM
HEAT
Following
Schedule
In
s
i
de
Outside
Se
t T
o
M22453
Table 12. Sensor Resistance at Outdoor Temperature.
Outdoor
Temperature
Ohms of
Resis-
tance
Outdoor
Temperature
Ohms of
Resis-
tance°F °C °F °C
-20 -28.9 106926 52 11.1 17136
-18 -27.8 100923 54 12.2 16387
-16 -26.7 95310 56 13.3 15675
-14 -25.6 90058 58 14.4 14999
-12 -24.4 85124 60 15.6 14356
-10 -23.3 80485 62 16.7 13743
-8 -22.2 76137 64 17.8 13161
-6 -21.1 72060 66 18.9 12607
-4 -20.0 68237 68 20.0 12081
-2 -18.9 64631 70 21.1 11578
0 -17.8 61246 72 22.2 11100
2 -16.7 58066 74 23.3 10644
4 -15.6 55077 76 24.4 10210
6 -14.4 53358 78 25.6 9795
8 -13.3 49598 80 26.7 9398
10 -12.2 47092 82 27.8 9020
12 -11.1 44732 84 28.9 8659
14 -10.0 42506 86 30.0 8315
16 -8.9 40394 88 31.1 7986
18 -7.8 38400 90 32.2 7672
20 -6.7 36519 92 33.3 7372
22 -5.6 34743 94 34.4 7086
24 -4.4 33063 96 35.6 6813
26 -3.3 31475 98 36.7 6551
28 -2.2 29975 100 37.8 6301
30 -1.1 28558 102 38.9 6062
32 0.0 27219 104 40.0 5834
34 1.1 25949 106 41.1 5614
36 2.2 24749 108 42.2 5404
38 3.3 23613 110 43.3 5203
40 4.4 22537 112 44.4 5010
42 5.6 21516 114 45.6 4826
44 6.7 20546 116 46.7 4649
46 7.8 19626 118 47.8 4479
48 8.9 18754 120 48.9 4317
50 10.0 17926 —