Installation Manual

ManualsBrandsBosch ManualsCooling & Air QualityAquastar 2700ES Natural Gas Tankless Water Heater

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Installation instructions

Fig. 32 Plumbing Connections (with shutoff valves)

and Pressure Relief Valve

1 Water filter

3.11 Domestic hot water recirculation

The following drawing is provided to outline one

possible recirculation design using the water heater in

conjunction with an Ariston mini tank water heater.

Recirculation directly through the tankless water heater

is also allowed. 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.

Fig. 33 Recirculation application

1 Full port isolation valve

2 Circulator (pump)

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 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 Water

Heating 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. 35).

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 14.

Operating Pressure Test

B Press ON/OFF button to turn off the appliance.

B Press and hold "Program" (P) button and press ON/

OFF button to turn appliance ON.

Fig. 34

B As soon as '188' is displayed, release "Program"

, button and the display should read P2.

B Press or until P1 appears.

Note: While in this mode the appliance will run

constantly at maximum power and allow

maximum water flow.

For inlet gas pressure adjustment consider the

following table:

B Turn on high volume of hot water flow (at least 6

gpm) and heater will ignite. If heater display reverts to

P2, open more hot water fixtures to allow sufficient

flow. Press until P1 reappears on display.

6720608158-77.1AL

Ariston Minitank

GWH

2700

Gas type NG LPG

3.5” WC 8” WC

Table 13 Minimum inlet gas pressure under full operation