Domestic Hot Water Recirculation; Measuring Gas Pressure - Bosch Evolution 500 Instruction Manual

Installation instructions
the water heater as possible. See Fig. 31. To install the
PRV, a suitable fitting connected to an extension on a
"T" fitting can be sweated to the hot water line.
Support all piping.
Fig. 31 Plumbing Connections (with shutoff valves)
and Pressure Relief Valve
1 Water filter

3.11 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. 32. By using the design in Fig. 32, 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 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.
26
5
1
Ariston Minitank
Fig. 32 Recirculation application
1 Full port isolation valve
2 Circulator (pump)
3 Check valve
4 PRV
Expansion tank
5
The use of a small electric mini-tank water 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.

3.12 Measuring gas pressure

Confirm gas pressure upon installation.
Connecting manometer
B Shut off gas supply at installer supplied shutoff valve
for this water heater.
B Remove front cover and locate inlet gas pressure
measuring point (see Fig. 34).
B Loosen screw inside left test point fitting (do not
remove) and connect manometer tube to test point.
Remove screw completely if correct size tapping is
available.
Static Pressure Test
B Turn gas supply back on.
B Record static gas pressure reading in table 15.
Operating Pressure Test
B Press ON/OFF button to turn off the appliance.
Evolu-
tion
500
2
4
3
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