Checking The Gas Rate; Checking For Gas Leaks During Operation; Gas Supply Pressure Drop; Allowed Mbar Pressure Drop - Worcester Greenstar 4000 Installation And Maintenance Instructions Manual

Commissioning
Commissioning must not take place outside of the permissible pressure
range. If necessary:
▶ Identify the cause and rectify the fault.
▶ If this is not possible: isolate the device on the gas side and notify the
gas supplier.
▶ Exit the chimney sweep mode.
▶ Switch off the appliance, close the gas isolator, remove the pressure
gauge and tighten the screw.
▶ Refit the casing.
Gas pressure within the system
Combi appliances
▶ Running a hot water tap does not guarantee the appliance will
operate at maximum output throughout the test.
Natural Gas or LPG pressures.
The pressure drop from the meter or at the LPG gas supply to the gas
valve inlet test point must not be more than the values stated in table 21.
If the pressure drops are greater than shown in table 21, then this would
indicate a problem with the pipework or connections within the system.
NOTICE
▶ Do not continue commissioning until the correct gas pressure is
achieved with the appliance running at maximum output.
Gas Meter/LPG Across
Type supply pipework

Allowed mbar pressure drop

NG 19 - 23 1
LPG 32 - 45 2.5
Table 21 Allowed mbar pressure drop

Gas supply pressure drop

Natural Gas
Meter
19 - 23 mbar
Appliance inlet
1.0 mbar
drop
18 - 22 mbar
Fig. 65 Natural Gas pressures
[A] Pressure loss across the appliance
[B] Pressure reading at inlet test point
46
Appliance Across Gas valve
inlet appliance inlet test
[A] point [B]
18 - 22 1.5 16.5 - 20.5
29.5 - 42.5 1.5 28 - 41
mbar range
Gas Control
valve
Inlet test point [B]
Across appliance
drop [A]
0010012820-001
L.P.G.
LPG Storage
32 - 45 mbar
0.5 mbar drop
Regulator
Appliance inlet
2.0 mbar
drop
29.5 - 42.5 mbar
Fig. 66 LPG pressures
[A] Pressure loss across the appliance
[B] Pressure reading at inlet test point
6.6

Checking the gas rate

The appliance must be running at maximum output rate when
performing the gas rate check, ( chapter 6.4.1).
▶ The gas rate should be measured at the gas meter after the appliance
has been operating for a minimum of 10 minutes at maximum
output.
▶ Refer to Technical data section of this manual for the appliance gas
rates and CO/CO ratios.
2
▶ Where a gas meter is not available (e.g. LPG) the CO/CO
checked.
▶ Gas rate must be checked with the appliance in service, maximum
output test mode.
▶ Carry out gas rating as per the latest advice in the Gas Safety
(Installation and Use) Regulations.
▶ Ensure all other gas appliances are isolated when carrying out the gas
rate check on the appliance.
▶ Set the chimney sweep mode and start up the appliance at maximum
rated output.
– Ensure that the appliance has stabilised at maximum output.
▶ Where a gas meter is not available (e.g. LPG) the CO/CO
checked to the units shown in the setting of the air/gas ratio.
▶ If pressure and gas rate are satisfactory press ok or d and the boiler
will return to normal operation.
– If left in the service mode the control will return to normal
operation after 15 minutes.
▶ Close the gas isolation valve.
▶ Remover the manometer.
▶ Re-seal the screw in the gas inlet pressure test point.
▶ Open the gas isolation valve and ensure there are no gas leaks.
6.7

Checking for gas leaks during operation

▶ Use an approved gas sniffer or leak detection fluid to check all
connections for possible leaks. Leak detection fluid must be certified
as a gas leak testing agent.
▶ Do not allow leak detection fluid to come into contact with the
electrical components.
Greenstar 4000 – 6 720 891 162 (2020/09)
Gas Control
valve
Inlet test point [B]
Across appliance
drop [A]
0010012821-001
must be
2
must be
2