Checking The Outside Temperature Sensor - Viessmann VITODENS 200-W Installation And Service Instructions Manual

Repairs
(cont.)
04. Remove the 4 screws from the fitting assembly.
05. Raise the boiler so that the connections are sepa-
rated and remove from the wall.
06. Before mounting the boiler, insert new O-rings.
Lubricate the O-rings with the valve grease sup-
plied.
07. Insert new flat gasket for the gas shut-off valve.
08. Danger
Avoid injury to the hands.
Do not grip the boiler underneath at the
back.
Fitting the boiler:
■ Position the boiler centrally in front of the wall
mounting bracket. Use the outer ends of the wall
mounting bracket to line up the boiler.
Lower the boiler vertically into position.
■
■ The supporting surface of the boiler must rest on
the fitting assembly.

Checking the outside temperature sensor

X3
Fig. 32
200
100
80
60
40
20
10
8
6
-20 -10 0 10 20
Temperature in °C
Fig. 33 Sensor type: NTC 10 k
30
Ω
09. Insert 4 screws into the fitting assembly from
below.
!
Please note
Tighten screws enough
to ensure the components do not suffer
damage and will function correctly.
Never tighten the screws with a cordless
screwdriver.
10. Tighten the union nut on the gas pipe.
Danger
Escaping gas leads to a risk of explosion.
Check the fitting for gas tightness.
1. Disconnect plug "X3" from the control unit.
2. Test the resistance of the outside temperature sen-
sor across terminals "X3.1" and "X3.2" on the dis-
connected plug and compare it with the curve.
3. In the event of severe deviation from the curve,
disconnect the wires at the sensor and repeat the
test on the sensor itself.
4. Depending on the result, replace the lead or the
outside temperature sensor.
Troubleshooting
73