Function Description; Control Unit - Viessmann FB2B Installation And Service Instructions Manual

Control unit

Boiler temperature
Heating
DHW
Solar energy
Information
Select with
Heating mode
The control unit determines a set boiler
water temperature subject to outside
temperature or room temperature (if a
room temperature-dependent remote
control is connected) and to the slope/
level of the heating curve.
The determined set boiler water temper-
ature is transferred to the burner control
unit. From the set and actual boiler water
temperatures, the burner control unit cal-
culates the modulation level and regu-
lates the burner accordingly.
Heating the DHW primary cylinder from cold
The heating circuit pump is switched ON
and the three-way diverter valve will be
changed over, if the cylinder tempera-
ture sensor captures a temperature
lower than the defaulted set tempera-
ture.
48 °C
(
The electronic temperature limiter inside
the burner control unit limits the boiler
water temperature.
■ The cylinder primary pump is switched
ON if the boiler water temperature ≥
set DHW temperature.
■ The burner is switched ON if the boiler
water temperature ≤ set DHW temper-
ature, and the cylinder primary pump
is switched ON when the required
boiler water temperature is reached.

Function description

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