Domestic Hot Water Recirculation; Space Heating Applications - Bosch Therm C 1210 ES Installation And Operating Instructions Manual

Installation instructions
▶ Check water level in the condensate trap.
Fig. 38 Water level in condensate trap
▶ After filling reassemble all parts in reverse order.

4.12 Domestic hot water recirculation

Although recirculation directly through the tankless water
heater is allowed, temperature stability is improved by
recirculating through a mini-tank as shown in fig. 39. By using
the design in fig. 39, there is no recirculation of hot water
through the tankless water heater and therefore, does not
affect the heat exchanger warranty. Direct recirculation
through the tankless water heater is permissible, however, the
heat exchanger warranty is reduced; contact Bosch
Thermotechnology for further installation requirements. The
following drawing is provided to outline one possible
recirculation design using the water heater in conjunction with
a Bosch electric mini tank water heater. This schematic is for
illustration only and must not be used for actual Installation
without appropriate engineering and technical advice from a
properly licensed professional in the locality where the
installation is made.
42
Fig. 39 Recirculation application
[1] Full port isolation valve
[2] Circulator pump on timer
[3] Check valve
[4] PRV
[5] Expansion tank
[6] C 1210 ES/ESC
[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 1210ES/ESC – 6 720 644 887 (2022/04)