Space Heating Applications - Bosch C 950 Installation Manual

4.13

Space heating applications

CAUTION:
▶ If the set point temperature is above 120°F,
precautions should be taken to protect users of
potable water from scalding.
CAUTION:
▶ Propylene glycol may be used for freeze prevention
ONLY on the space heating side of the heat
exchanger. Do not use ethylene glycol (automotive
antifreeze).
CAUTION:
▶ The use of a flow switch is recommended to ensure
DHW priority and to prevent "cold-blow" situations
when the Bosch tankless water heater is used with an
air-handling system. The flow switch should be used
to disable the blower on the air-handling system
when domestic water is used.
Fig. 44 Space heating diagram
[1] Hot water outlet
[2] Cold water inlet
[3] Pressure relief valve
[4] Gas supply
[5] Shut off gas valve
[6] Thermal expansion tank (as required)
[7] Atmospheric vacuum breaker
[8] Cold inlet
[9] Check valve
[10] Pump
[11] Thermostatic mixing valve
[12] Thermometer (optional)
[13] DHW outlet
[14] Water to water heat exchanger
Greentherm
CAUTION:
▶ Ensure the primary pump is properly sized to provide
adequate flow for the system heat load.
For Pump sizing please refer to the pressure drop
curves, fig. 45. Also remember to account for system
piping pressure loss. A minimum of 1.7 GPM is
recommended to provide adequate flow through the
water heater when determining the size of the primary
pump.
Bosch tankless water heaters are approved for use in combination DHW
and space heating applications (open-loop setup). These water heaters
are not approved for use in space heating only applications (closed-loop
setup). Bosch supports applications of combination DHW and space
heating in an open loop configuration if plumbed similar to fig. 44. Use of
a Bosch tankless water heater in a combination DHW and space heating
application will result in the product warranty being reduced to 3 years.
[17] Thermostat
[18] Space heating zone
[19] Zone controller
[20] Space heating pump
[21] Expansion tank
[22] Pressure relief valve
Installation instructions | 35
6 720 805 440 (2014/11)