Viessmann VITOPEND 100-W Installation And Service Instructions Manual page 40

Function description
DHW heating
Gas fired central heating boiler
The burner, the circulation pump and
the three-way valve are started or
changed over, if the cylinder tempera-
ture falls 2.5 K below the set cylinder
temperature.
Gas fired combi boiler
If the flow switch recognises that
DHW is drawn off (> 3 l/min), the burn-
er and circulation pump are switched
ON and the three-way valve changes
over to DHW heating.
Extension for external connections (accessory)
The external extension H3 can be
connected to the Vitopend 100-W
control unit.
Installation instructions
External extension H3
With the external extension H3
extractor fans can be locked out in
case of open flue operation.
40
The set boiler water temperature is up
to 20 K higher than the set cylinder
temperature. The burner will be
switched OFF and the cylinder pri-
mary pump run-on time will start, if the
actual cylinder temperature exceeds
the set cylinder temperature by 2.5 K.
The burner modulates to reach the
DHW outlet temperature and is limited
on the boiler side by the temperature
limiter (84 °C).