Honeywell C7089 - Manuel (Page 3)

C7089 OUTDOOR SENSOR
3 69-1709EFS
OPERATION
Once installed and the Thermostat Installer Setup
Number 0340 is set to 1 or 2, the outside temperature
can be displayed on the thermostat. See Fig. 3.
Fig. 3. 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 1.
CHECKOUT
Allow C7089B 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 1.
CALIBRATION
The C7089 Outdoor Sensor is calibrated at the factory and can-
not be recalibrated in the field.
Heat On
SCHED HOLD CLOCK SCREEN MORE
MON TUE WED THU FRI SAT AAT SUN
AM
FAN
AUTO
SYSTEM
HEAT
Following
Schedule
Outside
Set To
M19971
Table 1. Sensor Resistance
at Outdoor Temperature .
Outdoor Temperature
Ohms of
Resistance °F °C
-20 -28.9 106926
-18 -27.8 100923
-16 -26.7 95310
-14 -25.6 90058
-12 -24.4 85124
-10 -23.3 80485
-8 -22.2 76137
-6 -21.1 72060
-4 -20.0 68237
-2 -18.9 64631
0 -17.8 61246
2 -16.7 58066
4 -15.6 55077
6 -14.4 53358
8 -13.3 49598