Hamworthy Purewell Installation, Commisioning And Maintenance Instructions page 24

correctly located within the pocket. Do not force the
bulb into the pocket by placing undue stress on the
capillary. Close fascia and re-fit top panel correctly.
Run the boiler and turn the thermostat up and down
to check for correct operation. Set thermostat to
previously noted setting.
14.3 Temperature Limiter (Limit Stat) Renewal
Part No. 533901168/533901180 (ECO type) or
533901179/33911044 (Pilot Stat Models)
The temperature limiter renewal procedure follows that
of the control thermostat with some minor differences.
These are as below: -
Remove the 'push on' spade connections from the
temperature limiter body noting position of coloured
cables. Remove plastic cover (if fitted) and unscrew
holding nut/screws to detach temperature limiter from
housing. Gently feed the capillary back through the
controls bulkhead. Set temperature limiter to 100°C
and assemble into controls housing ensuring correct
cable notation. Refer to the thermostat diagram if
terminal identification differs from those given in Figure
No. 13, (Boiler schematic wiring diagram).
14.4 Main Gas Valve
NOTE! Some gas valve components can be replaced
without completely removing the whole assembly from
the boiler. However, Hamworthy 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.
NOTE! Only gas valves with an identical type No. may
be used for replacement. Please contact Hamworthy
Heating Spares dept. for further information.
Various types and manufacturers of gas valves are
used. Refer to Figure No. 16 for alternative type of
valve fitted.
1) Ensure power and gas supplies are isolated.
2) To remove the gas valve first undo and remove the
pilot bundy tube, thermocouple, ECO connections (if
fitted) and the piezo spark generator bracket.
3) Remove the gas valve wiring plug from the socket
in the controls housing by un-doing both screws and
pulling firmly downwards. Undo the union connection
and 8mm nuts holding the gas valve/manifold
assembly to front plate, this will allow the whole
assembly to be removed from the boiler.
4) Remove the gas valve by unscrewing cap head
screws or screwed fitting holding valve to pipework.
NOTE! The position of the relevant electrical cables
should be noted.
When replacing the gas valve, it is advisable to renew
the 'O' ring seals (if fitted). See Section
HAMWORTHY HEATING LTD.
15.0 RECOMMENDED SPARES for Part Nos. Do
not over tighten cap head screws in gas valve body.
Ensure electrical plugs are firmly and correctly located
and holding screws are tightened.
5) Replace assembly ensuring correct orientation of
the gas valve. Ensure that the gas flow is in the same
direction as the arrow on the valve. Refit all external
components and replace plug into controls housing
socket, re-fit and tighten screws holding plug to
housing. Switch on gas and power supply and check
for integrity of all joints using a proprietary leak
detector.
Ensure gas valve's operation is correct and safe before
continuing. Refer to Figure No. 3 if necessary, for
valve integrity check procedure.
6) Re-light the boiler using instructions on the inside
of the door. Check and adjust the manifold gas
pressure, refer to Figure No. 1 or Appendix 'A' for
correct setting relating to the boiler size installed.
If necessary, refer to Section 11.4: Commissioning
the Boiler, for correct procedures.
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PUREWELL PERMANENT IGNITION 500001045/F