Viessmann WB1A007 Installation And Service Instructions Manual page 34

Boiler Connections
Installation Examples
Boiler in heating/cooling application
Heating/Cooling unit
Spring-loaded flow check valve
Circulation pump
Expansion tank
Water chiller
Boiler circuit pump (field supplied)
34
(continued)
v2
v1
IMPORTANT
Viessmann strongly suggests that the
valves pictured above be labelled "v1"
and "v2".
The boiler, when used in connection
with a refrigeration system, must be
installed ensuring the chilled medium is
piped in parallel to the boiler with
appropriate valves to prevent the
chilled medium from entering the boiler.
See illustration on the left.
The boiler piping system of a hot water
heating boiler connected to heating
coils located in air handling units where
they may be exposed to refrigerated air
circulation must be equipped with flow
control valves or other automatic
means to prevent gravity circulation of
the boiler water during the cooling
cycle.
Check installation instructions of the
chiller manufacturer carefully for
additional requirements.
Cooling season starts:
Close valve v1 and open valve v2.
Heating season starts:
Close valve v2 and open valve v1.