Checking The Gas Inlet Pressure - Worcester 29CDi Classic Installation, Commissioning And Servicing Instructions

COMMISSIONING
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
Inlet pressure
test point
Fig. 53 Inlet pressure test point
▶ Close gas isolation valve.
▶ Slacken the screw in the inlet pressure test point a quarter turn and
connect a manometer.
▶ Open gas isolation valve.
▶ Measure the pressure with the boiler running at maximum.
– Press the Performance test button (J) for more than ten seconds
and set Central Heating temperature to maximum.
– The Performance test button (J) will illuminate continually and the
display (C) will alternate between
temperature.
▶ Check the gas supply working pressure at the gas valve conforms to
values shown in Fig. 54 or Fig. 55 .
Ensure inlet pressure is satisfactory with all other gas
appliances working.
NOTICE: Do not continue commissioning until the
correct gas inlet pressure is achieved.
▶ If pressure is satisfactory press the Performance test button (J) again
and the boiler will return to normal operation.
▶ If left in the Performance test mode the control will return to normal
operation after 15 minutes.
▶ Close the gas isolation valve and remove the manometer.
▶ Re-seal the screw in the gas inlet pressure test point.
▶ Open the gas isolation valve and check for gas tightness.
GAS PRESSURE WITHIN THE SYSTEM
Refer to the figure below for natural gas pressures.
The pressure at the boiler must not be less than the pressure read at the
meter minus 1 mbar.
The pressure drop from the meter to the gas valve must not be more than
2.5 mbar for natural gas.
If the pressure drops are greater than shown in figure 54, then this
would indicate a problem with the pipe work or connections within the
system.
34
6720647361-58.1Wo
and the central heating flow
Meter
Natural Gas
< 2.5mbar
difference
19 - 23 mbar
Boiler inlet
1 mbar
drop
18 - 22 mbar
Fig. 54 Natural gas pressures
Refer to the figure below for L.P.G gas pressures.
The pressure at the boiler must not be less than the pressure read at the
meter minus 2.5 mbar.
The pressure drop from the meter to the gas valve must not be more than
4 mbar for LPG.
If the pressure drops are greater than shown in figure 55, then this
would indicate a problem with the pipe work or connections within the
system.
Regulator
L.P.G.
< 4.0mbar
difference
32 - 45 mbar
Boiler inlet
2.5 mbar
drop
29.5 - 42.5 mbar
Fig. 55 L.P.G. pressures
NOTICE:
Do not continue commissioning until the correct gas
pressure is achieved.
Gas Control
valve
16.5 - 20.5 mbar
1.5 mbar
drop
6720644744-44.2Wo
Gas Control
valve
28 - 41 mbar
1.5 mbar
drop
6720644744-45.2Wo
6 720 815 725 (2015/05)