Space Heating Applications - Bosch C 950 Installation And Operation Instruction Manual

Fig. 43 Recirculation application
[1] Full port isolation valve
[2] Circulator pump on timer
[3] Check valve
[4] PRV
[5] Expansion tank
[6] Greentherm
[7] Bosch electric minitank
The use of a small electric mini-tank after heater (4-6 gallon
size) should be used for this application and designed so the
pump will circulate the water through the mini-tank and the
building's hot water return loop only. Timed or thermostatically
controlled operation of the pump is commonly done. Contact
Bosch Thermotechnology if further information is needed.

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).
C 950/C 1050 (Pro TL 175 C/199 C) – 6 720 805 440 (2019/10)
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.
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.
Installation instructions
47