Honeywell C7089 - Operation; Displaying Outdoor Temperature; Checkout; Verifying Sensor Performance

OPERATION
Once installed and the Thermostat installer Setup
Number 8346 is set to 1 or 2, the outside temperature
can be displayed on the thermostat. See Fig. 3.
7
TUE
iC
Heat On
FoltowingSchedule
HE_ Outside
-t.I I_- _,, t-- t--I
rT-S t----!----I
M19971
Fig. 3. Outside temperature reading on
TH8000 Series Thermostat.
C7089 OUTDOOR SENSOR
The C7089 Outdoor Sensor converts outdoor ambient
temperature to a resistance that the thermostat can
interpret.
The C7089 has a negative temperarule coefficient (TC), which
llleans that lesistance decreases as
tile rempelature incleases. See Table 1
CHECKOUT
Allow C7089B Outdoor Sensor to absorb outdoor air for a
minimum of twenty minutes before taking a reading.
With an accurate thermometer (:t:l°F [O.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 1.
CALIBRATION
The C7089 Ourdool Seilsor is caliblared at tile fucroly and can-
nor be recalibrated in tile field
-2O
-18
-16
-14
-12
-10
-8
-6
-4
-2
O
2
4
6
8
Table 1. Sensor Resistance
at Outdoor Temperature.
Outdoor Temperature
°F °C
-28.9
-27.8
-26.7
-25.6
-24.4
-23.3
-22.2
-21.1
-20.0
-18.9
-17.8
-16.7
-15.6
-14.4
-13.3
Ohms of
Resistance
106926
100923
95310
90058
85124
80485
76137
72060
68237
64631
61246
58066
55077
53358
49598
3 69-1709EFS