HAMWORTHY HEATING LTD
WESSEX-HE 200 BOILER
500001008/K
19
contact Hamworthy Heating Spares Dept. for
further information
.
a) Remove the gas valve wiring plugs at the valve to
be removed by loosening plug-retaining screws.
b) Loosen the 4 cap head screws securing the
outlet (front) manifold to the gas valve, which is not to
be changed and remove the 8 cap head screws
securing the inlet and outlet of the valve to be
changed.
c) The pipework should spring sufficiently for the
valve to be removed together with its sealing `o’ ring
at either end.
d) Select new valve and check it is identical to that
being replaced and it is in the correct orientation
(check arrow on valve). It is advisable to fit new `o’
ring seals at either end. Re-align the new valve with
the manifolds and replace and tighten the cap head
screws. Ensure `o’ ring seals remain in correct
position. Re-tighten the 4 cap head screws on
second valve also ensuring `o’ ring seal is correctly
located.
e) Re-connect the gas valve wiring plugs at the
valve and secure.
This method can also be employed to check the inlet
filters on each valve if lack of gas flow Is suspected.
On completion, check all disturbed joints for gas
leakage and re-commission the boiler as detailed in
sections 11.4 and 11.5.
14.5 Differential Pressure Switch Renewal
- HHL
Part No. 533901394
The differential pressure switch is located on the left-
hand side of the fan casing and attached to the gas
feed pipe fabrication.
Remove cover by releasing the 2 screws. Disconnect
wires from terminals and remove cable by releasing
gland. Release bundy tube nuts at elbow and straight
fitting on switch. Remove fittings and refit to new
switch in the appropriate positions using suitable
sealant.
NOTE!
When fittings are removed from switch
ensure that holes are clear of any obstruction and
jointing compound before re-fitting to new switch.
Fit new switch in reverse order ensuring the
appropriate joints are gas tight and connect wiring
through gland as indicated:
a) White/Red wire to terminal marked "2" (NO).
a) White wire to terminal marked "3" (COM).
c) Green/Yellow wire to earthing terminal.
Tighten cable gland.
Check switch is set to 1.2 mbar and replace cover
plate. Start the boiler several times to check for
reliability.
14.6 Control Thermostat Renewal
- HHL Part No.
533901178 or 339009345
Alternative thermostat manufacturers may be used in
the Wessex boiler controls assembly. However, the
fitting and wire spade connections are physically
identical. The terminal identification may well be
different from that shown on the wiring diagram.
Please refer to diagram included on the thermostat to
ensure correct connections are made and correct
operation is obtained.
To replace the thermostat the following procedure
must be followed.
NOTE!
Record existing
temperature setting of thermostat for reference before
removal.
Remove thermostat capillary retaining clip at pocket
and withdraw the bulb from the pocket in the flow
elbow. Remove the PINK and RED/BLUE leads at
the "push-on" terminals on the thermostat body. Pull
off the control knob and remove the spring and bezel.
The thermostat is retained to the support bracket by
two M3 screws, one of which is a pillar type and
forms the control knob stop. Take care to note the
relative position of the two screws before removing
them (i.e. the lower screw has a pillar head), together
with the thermostat body.
Re-assemble the new thermostat in reverse
procedure ensuring that the leads connect the
thermostat in the normally closed position. (Identified
as contacts 1 and 2 or C and NC on the thermostat
body.) Run the boiler and turn the thermostat up and
down to check for correct operation during the warm
up period.
14.7 Temperature Limiter Renewal
- HHL Part
No.533901179 or 339011044
Firstly remove the fascia as described in 13.2.1.
Remove sequence control box by loosening central
screw and pulling out.
Remove thermostat capillary retaining clip at pocket
and withdraw the bulb from the pocket in the flow
elbow. Remove the YELLOW, GREY and RED/
BLUE leads at the "push-on" terminals on the limiter’s
body. Undo the bulkhead nut and withdraw the
limiter.
Fit the new temperature limiter in reverse order
ensuring that the YELLOW lead connects to common,
the RED/BLUE lead connects the normally closed
position and GREY the normally open position.
