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Applications Manual Bosch Greenstar | 33
Bosch Thermotechnology Corp.
Data subject to change
2.6 System 6: Greenstar Combi Boiler in a
single zone system
Summary:
Single combi-boiler supplying one heating zone. Outdoor
reset with FW200 controller with built-in room sensor
mounted in the living space for room feedback. DHW
generation directly off the boiler through the tankless heat
exchanger. This system is using the boiler pump for zone
water circulation.
The “combi” or combination boiler is a high effi ciency
central heating boiler and water heater combined within
one compact unit. Water is heated on demand directly
from the water main eliminating the need for a hot water
storage tank.
Single boiler with primary/secondary piping confi guration
supplying one heating zone. Outdoor reset with FW200
controller and room sensor mounted in the living space for
room feedback.
Use this design where System 2 cannot be used due to too
great a system pressure drop. Primary/secondary piping is
also required for radiant fl oor and panel radiator applica-
tions.
Primary/secondary piping isolates the system fl ow from
the boiler fl ow and prevents the system from infl uencing
boiler performance.
In detail:
The FW200 is an outdoor temperature based controller
with room temperature infl uence. The controller adjusts
the heating curve (boiler supply temperature) according
to outdoor temperature. When the FW200 is wall mounted
as a room sensor, it uses room temperature to adjust the
heating curve and modify boiler supply temperature ac-
cordingly.
FW200 provides warm weather shutdown.
For temperature sensitive radiant fl oor applications, install
a thermostatic tempering valve for overheat protection.
Required components:
Greenstar combi-boiler.
FW200 controller in the room.
Primary/secondary piping and system pump.
Thermostatic mixing valve (optional - overheat
protection for temperature sensitive floors).
Additional instructions:
See manufacturer’s installation and operating instructions.
Install an adequately sized Pressure Relief Valve (PRV) on
the DHW outlet of the combi boiler.
To reduce the risk of scalding it is recommended to install
a DHW tempering valve.
The Greenstar combi boiler is equipped with an internal
3.17 gal (12 liter) expansion vessel. The installation
manual provides information on how to determine if it is
of suffi cient capacity for the application or if an additional
expansion vessel is needed.