Bosch Greenstar 12i Service Manual download pdf (Page 39)

COMMISSIONING

6 720 644 743b (2011/08)

5.5 COMMISSIONING

Having checked:

B That the boiler has been installed in accordance with

the installation instructions.

B The integrity of the flue system and flue seals, as

described in section 6.3 of this manual.

B The integrity of the boiler combustion circuit and

relevant seals.

5.5.1 CHECKING THE GAS INLET PRESSURE

The inlet pressure to the appliance must be checked

using the following procedure:

MEASURING THE INLET PRESSURE

Fig. 62 Inlet pressure test point

B Close gas isolation valve.

B Slacken the screw in the inlet pressure test point (1)

and connect a manometer.

B Open gas isolation valve.

B Measure the pressure with the boiler running at

maximum.

– Press service button for more than ten seconds

and set Central Heating temperature to maximum.

– The service button will illuminate continually and

the blue power indicator will pulse five times.

B Check the gas supply working pressure at the gas

valve conforms to values shown in Fig. 63 or Fig. 64.

GAS PRESSURE WITHIN THE SYSTEM

Refer to the figures below for natural gas or L.P.G gas

pressures.

The pressure at the boiler must not be less than the

pressure read at the meter minus:

• 1 mbar for Natural Gas

• 2.5 mbar for L.P.G.

The pressure drop from the meter to the gas valve must

not be more than:

• 2.5 mbar for Natural Gas

• 4 mbar for L.P.G.

If the pressure drops are greater than shown below,

then this would indicate a problem with the pipe work or

connections within the system.

Fig. 63 Natural gas pressures

Fig. 64 L.P.G. pressures

NOTICE: The combustion settings on this

gas-fired boiler have been checked, adjusted

and preset at the factory for operation on

the gas type defined on the data plate.

No measurement of the combustion values is

necessary provided there is a meter installed

allowing the gas rate to be checked.

DO NOT ADJUST THE AIR/GAS RATIO VALVE.

When running in the service mode, the boiler

will operate both the central heating and the

domestic hot water circuits. This is to allow

sufficient time for this part of the

commissioning procedure. It will be

necessary to run water through the domestic

hot water circuit to ensure that the boiler will

not cycle on low heating demands.

6720643895-53.1Wo

Ensure inlet pressure is satisfactory with all

other gas appliances working.

≤ Equal to or less than .....

NOTICE:

Do not continue commissioning until the

correct gas pressure is achieved.

Meter

Boiler inlet

Gas Control

valve

19 - 23 mbar

18 - 22 mbar

16.5 - 20.5 mbar

1 mbar

drop

1.5 mbar

drop

Natural Gas

< 2.5mbar

difference

6720644744-44.2Wo

Gas Control

valve

L.P.G.

< 4.0mbar

difference

Regulator

Boiler inlet

32 - 45 mbar

29.5 - 42.5 mbar

28 - 41 mbar

2.5 mbar

drop

1.5 mbar

drop

6720644744-45.2Wo

1 2 ... 34 35 36 37 38 39 40 41 42 43 44 ... 71 72

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Bosch Greenstar 12i Service Manual Page 39

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