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Troubleshooting
Corrective Action
X3
Fig. 20
A
%
X3
Fig. 21
60
Check outdoor temperature sensor
600
580
560
540
520
500
480
460
440
420
400
+14 +32
-40 -22 -04
Outdoor temperature in ºF
-40
-30 -20
-10
0 +10 +20 +30
Outdoor temperature in ºC
Check boiler temperature sensor, tank temperature sensor or
supply temperature sensor of the low-loss header
1. Pull plug "X3" from the control unit.
2. Test the resistance of the outdoor
temperature sensor across terminals
"X3.1" and "X3.2" on the
disconnected plug and compare it
with the curve.
3. Where actual values strongly deviate
from the curve values, disconnect
the wires at the sensor and repeat
test immediately at the sensor.
4. Depending on result, replace the
cable or the outdoor temperature
sensor.
+50 +68 +86
1. Boiler temperature sensor:
Pull cables from boiler water
temperature sensor A and
check resistance.
DHW Tank temperature sensor:
Pull plug % from the cable harness
at the control unit and check
resistance.
Supply temperature sensor:
Pull plug "X3" from the control
unit and check the resistance
across terminals "X3.4" and
"X3.5".
Continued...
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