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Domestic Hot Water Recirculation With External Pump - Bosch Greentherm 9800 SE 160/199 Manual

Indoor residential and comme rcial tankless water heaters
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32 | Installation instructions
Fig. 23
Water filter
[1] Cap
[2] Water filter
WARNING: Appliance damage!
Appliance will overheat if not filled with water
▶ Ensure that the appliance is filled with
water by opening a hot water tap, before
plug in the water heater to the power
▶ The use of unions when connecting to the inlet and outlet
connections is recommended. This will facilitate any
necessary servicing.
▶ Plastic or PEX type plumbing materials are not suitable for
connecting directly to or within 18" of the water heater.
▶ Although water piping throughout the building may not be
copper, we require that copper or suitably rated stainless
steel flex line be used for the water connections for 18" on
either side of the water heater (follow local codes if more
▶ Never sweat any piping directly to water connections, as
damage will occur.
▶ Keep water inlet and outlet pipes to no less than ¾"
diameter to allow the full flow capacity.
▶ If the cold and hot connections to the heater are reversed,
the heater will not function.
▶ Be certain there are no loose particles or dirt in the piping.
Blow out or flush the lines before connecting to the water
▶ Full port shutoff valves should be installed on both the cold
water supply and hot water outlet lines to facilitate
servicing the heater (see fig. 21).
▶ For installation on a private well system with a pressure
tank, the lowest pressure range setting recommended is
30-45 psi (2.06 - 3.1bar).
6 720 816 815 (2016/10)
4.11 Domestic hot water recirculation with
external pump
Direct recirculation through the tankless water heater is
permissible, however, the heat exchanger warranty is reduced;
see warranty at
The following drawing is provided to illustrate one possible
recirculation design. 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.
This appliance has been designed to permit recirculation by
controlling an external pump. For this function, the external
pump must be electrically connected to the appliance - Bosch
cable accessory is available
recirculation ( 6.5.3, A1 Recirculation) can be used.
Fig. 24
Recirculation application with a dedicated return
[1] Cold water supply
[2] Check valve field supplied
[3] Circulator pump field supplied
[4] Expansion tank field supplied
[5] Circulator cable accessory
[6] Greentherm 9800 SE / SEC
[7] PRV
[8] Shutoff valves field supplied
Greentherm 9800 SE 160/199 | SEC 199
TBD). All the features of



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