Hamworthy Wessex 100 M100 Installation, Commissioning And Servicing Instructions page 32

14.5 Main Gas Valve
Part Nos. Refer to Hamworthy Heating
NOTE! Some gas valve components can be
replaced without completely removing the whole
assembly from the boiler.
Heating strongly recommend that a new gas valve
assembly is fitted to ensure safe, reliable operation
of the boiler. Please refer to Hamworthy Heating
Technical Department before attempting to remove
components from the gas valve. Various types and
manufacturers of gas valves are used. Refer to
Figure 11.4.3 (p18) for particular valve fitted.
1) Ensure power and gas supplies are isolated.
2) Remove the two screws securing the control
panel as described in Section 13.2 clause 2) (p20).
3) Remove the gas valve wiring plugs from the
main valve and HI/LO operator by un-doing the
securing screws and pulling firmly away from the
valve.
4) Remove the four M5 cap head screws securing
the gas valve to the diecast inlet elbow, taking care
to support the weight of the valve. Withdraw the
Figure 14.5 Gas Pipe Fitting
NAT. GAS HOLE
ARRANGEMENT SHOWN
HAMWORTHY HEATING LTD
However, Hamworthy
CIRCLIP
'O' RING
GAS PIPE
WESSEX 100 M
valve and gas pipe. Remove the four M5 cap head
screws securing the gas valve to the diecast outlet
elbow. When replacing the gas valve, it is advisable
to renew the `O` ring seals sealing both ends. See
recommended spares section for Part Nos. Ensure
that the gas orifice plate is undamaged and
fitted into the recess in the die cast outlet elbow.
(Refer Figure 14.5). Do not over tighten cap head
screws in gas valve body.
5) Replace assembly ensuring correct orientation
of the gas valve. Ensure electrical plugs are firmly
and correctly located and holding screws are
tightened. Ensure that the gas flow is in the same
direction as the arrow on the bottom of the valve.
Switch on gas and power supply and check for
integrity of all joints using a proprietary leak
detector. Ensure gas valve operation is correct and
safe before continuing. Refer to Figure 5.6 (p7) if
necessary for valve integrity check procedure.
6) Re-light the boiler using instructions mounted on
the top of the control panel. Check and adjust, the
low fire and high fire gas pressures, refer to Figure
2.2 (p4) for correct settings. If necessary, refer to
Section 11.4, COMMISSIONING THE BOILER
(p16), for correct procedures.
SEALING WASHER
26
GAS VALVE
ORIFICE
DISC
500001080/F