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Applications Manual Bosch Greenstar | 25
Bosch Thermotechnology Corp.
Data subject to change
2.4 System 4: Greenstar Heating Boiler in a
single zone system with solar thermal
DHW and boiler backup
Summary:
Single boiler supplying one baseboard heating zone
equipped with FW200 outdoor reset controller with built-
in room sensor in the living space . This system is using
the boiler pump for zone water circulation and DHW tank
loading. A diverter valve is used to switch between space
heating and tank loading. This system is identical to Sys-
tem 3 with an added solar thermal DHW heating system.
This design can only be used with a single loop baseboard
system that has a low pressure drop. Radiant fl oors, panel
radiator, or multi zone systems require primary-secondary
piping. Do not install zone valves with this system.
Max. 70' (21 m) of 3/4" baseboard at a 20°F delta T and a
fl ow rate of 4.0 gpm plus the necessary supply and return
piping.
Ensure to select a solar tank with a boiler coil pressure
drop that does not exceed the capacity of the boiler pump
(see pages 11 & 12 for details).
Solar thermal provides renewable energy to heat DHW year
round, and if sized properly reduce energy consumption
signifi cantly. Bosch offers plug and play components
that are designed to work together with a boiler backup
system. Bosch solar thermal systems are qualifi ed for
government and utility incentives reducing the upfront
investment cost signifi cantly. Bosch solar thermal
collectors work even in the winter and under cloudy skies
preheating water, and reducing boiler run time and burner
starts.
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,
it also uses room temperature to adjust the heating curve
and modify boiler supply temperature.
FW200 provides warm weather shutdown.
The control of the solar thermal system is integrated with
the FW200 boiler control, and reduces boiler run time and
burner starts signifi cantly compared to independent sys-
tems. The solar pump will run whenever the collectors are
16°F (9°C) warmer than the bottom of the solar tank.
It is recommended to double the volume of the solar
thermal DHW tank compared to an equivalent conventional
indirect fi red DHW tank. This allows suffi cient backup
volume ("comfort zone") maintained by the boiler without
sacrifi cing capacity for solar harvesting.
Required components:
Greenstar combi-boiler.
FW200 controller in the room.
ISM2.
DHW solar tank with 2 coils.
Bosch solar thermal system complete.
Diverter valve 120VAC, 3-way, spring return.
Additional instructions:
See manufacturer’s installation and operating instructions.
The Bosch Greenstar boiler and ISM2 offer many different
solar thermal applications including space heating sup-
port and pool heating. Please consult the installation and
operating instructions for details.