Domestic Hot Water Recirculation - Bosch C 1210 ES Installation Manual

Installation instructions

3.12 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. 35. By using the design in Fig. 35, there is no
recirculation of hot water through the tankless water
heater and therefore, does not affect the heat
exchanger warranty of 15 years. Direct recirculation
through the tankless water heater is permissible,
however, the heat exchanger warranty is reduced to 3
years; 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 an Ariston
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.
5
1
Ariston Minitank
Fig. 40 Recirculation application
1 Full port isolation valve
2 Circulator on timer or aquastat
3 Check valve
4 PRV
5 Expansion tank
The use of a small electric mini-tank water heater (4-6
gallon size) should be used for this application and
designed so the circulator 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 Water Heating if further information is needed.
32
GWH
C 1210
ES/
ESC
2
4
3
6720608836-12.1AL
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