Viessmann Vitodens 100-W B1HA 26 Installation And Service Instructions Manual page 64

Troubleshooting
Boiler Connection
64
(continued)
Temperature
Vitodens 100-W, B1HA/B1KA 26 to 125 Combi Installation/Service
Check outdoor temperature sensor
1. Disconnect cables from outdoor sensor.
2. Measure resistance of the outdoor sensor and
compare with resistance / outdoor sensor curve
shown below.
3. If the value measured differs significantly, replace
the sensor.
In weather-compensated mode (optional), the boiler
water temperature is regulated subject to the outdoor
temperature.
Frost protection function
Built-in automatic frost protection allows the boiler to be
shut off for an extended period of time while protecting
it against freeze-up. Frost protection is continually active.
The burner is switched ON when the boiler water
temperature reaches 41ºF (5ºC) and is switched OFF
again when the boiler water temperature reaches at least
59ºF (15ºC) [but not more than 68ºF (20ºC)].
For details on the control, please refer to
the Vitodens 100-W Operating Instructions.