Viessmann Vitopend 100-W Installation And Service Instructions For Contractors page 47

DHW heating
(cont.)
Gas combi boiler
If the flow switch detects that DHW is
being drawn (> 3 l/min), the burner and
circulation pump start and the 3-way
valve changes over to DHW heating.
Extension for external connections (accessory)
The external extension H3 can be con-
nected to the Vitopend 100-W control
unit.
With the external extension H3, extractor
fans can be locked out in the case of
open flue operation.
Function description
The burner modulates to reach the DHW
outlet temperature. It is limited on the
boiler side by the temperature limiter
(84 °C).
Installation instructions
External extension H3
47