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Component Replacement - Page 40
6.26
Heat Exchanger
a
.
Perform 5.1 to 5.6 & 5.8 in 'Routine Maintenance'. Remove
the combustion chamber insulation by removing each side
panel retaining screw and pulling the complete side panel
/insulation assembly forwards. The rear insulation can
remain in situ.
b.
Close all the isolating valves, reduce the pressures in the
appliance by operating the pressure relief valve and
opening the lowest hot water tap. Drain the remaining water
in the boiler by removing the drain screws under the pump
manifold (C.H.) and on the 15mm isolating valve (D.H.W).
Undo the heat exchanger connection to the auto air vent
pipe.
c.
Disconnect the electrical connections from the C.H.
overheat thermostat. The control box should be protected
from water spillage.
d.
Release the four spring clips retaining the heat exchanger
tails by pulling the clip forwards and towards the centre of
the appliance and ease the heat exchanger up, out of the
housings.
e.
The heat exchanger waterways can now be descaled or a
replacement heat exchanger can be fitted, in which case
the overheat thermostat must be transferred to the new
heat exchanger.
f.
Re-assemble in reverse order. Use a soap solution to
lubricate the new 'O' rings when fitting the new heat
exchanger, also, ensure the heat exchanger is pushed fully
down. Re-charge the system as described in section 1.6
and check the joints for leaks.
6.28
Automatic Air Vent
a
.
Remove the white front case, base panel and white left
hand side panel. See 5.1, 5.2 & 5.3 in 'Routine
Maintenance'.
b.
Close the central heating isolating valves, reduce the
system pressure by opening the pressure relief valve, then
part drain the water from the boiler by opening the bleed
valve on the right hand side of the diverter valve.
c.
Using a spanner to prevent the retaining nut from rotating
unscrew the auto air vent and remove from the appliance. If
there is insufficient space, removal will be eased if the
complete auto air vent and pipe assembly is disconnected
from the heat exchanger and then raised above the top of
the air box. To do this the fan and fluehood will need to be
removed, see 5.4 & 5.5 in 'Routine Maintenance'
d.
Fit new air vent and sealing washer ensuring the air vent
cap is left loose.
Re-assemble in reverse order, ensure that the grommet is
correctly positioned. Re-charge the system as described in
section 1.6 and check for leaks.
6.29
Pressure Relief Valve
a.
Remove the white front case and base panel.
See 5.1 & 5.2 in 'Routine Maintenance'.
b.
Close the central heating isolating valves, reduce the
system pressure by opening the pressure relief valve, then
drain the water from the appliance by removing the drain off
screw on the underside of the pump manifold.
c.
Undo the outlet tube nut and fully remove the two grub
screws holding the pressure relief valve to the pump
manifold, undo the top compression joint on the pressure
relief valve discharge pipe then remove the valve
(Fig. 24).
(Fig. 35)
(Fig. 36)
.
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