6
For replacement of the following components it will
be necessary to remove boiler casing panels as des-
cribed in
‘Routine Cleaning and Inspection’.
WARNING:
Before commencing the replacement of
any component, isolate appliance from electrical
supply and turn off gas at service cock.
To replace domestic hot water thermostat
●
Locate domestic hot water thermostat phial poc-
ket in underside of storage cylinder.
●
Remove wire clip securing thermostat phial into
pocket.
●
Remove two screws from front control panel and
open panel.
●
Remove two leads from domestic hot water ther-
mostat.
●
Remove domestic hot water thermostat knob by
pulling off.
●
Using a suitable tool, unscrew and remove nut se-
curing thermostat to control panel.
●
Fit replacement control in reverse order to remo-
val.
●
Connect leads to terminals 1 and C. The polarity is
not important.
To replace fan
●
Remove fan as described in ‘
Routine Cleaning
and
Inspection
’.
●
Fit replacement fan in reverse order to removal.
●
Reconnect electrical lead.
To replace air pressure switch
●
Locate air pressure switch situated outside sealed
chamber on upper right hand side,
see diagram 5.
●
Remove sealed chamber cover as described in
‘
Routine Cleaning and Inspection
’.
●
Hold air pressure switch and remove two securing
screws.
●
Carefully pull off air sensing tubes.
●
Disconnect electrical leads to switch.
●
Fit leads to terminals of replacement switch.
●
Reconnect short air sensing tube to connection
marked
H
.
●
Reconnect long air sensing tube to connection
marked
L
.
●
Fit replacement switch to boiler in reverse order to
removal.
To replace printed circuit board (PCB)
●
Remove two screws from front control panel and
open panel.
●
Carefully pull off electrical connections to PCB.
●
Unscrew and disconnect two incoming mains wi-
res.
●
Unscrew and disconnect two mains warning light
wires.
●
Remove screws securing PCB to control panel and
lift out PCB.
●
Fit replacement PCB in reverse order to removal.
Note:
Make sure that PCB connections are fully
pushed onto replacement PCB.
To replace central heating thermistor
Drain down heating circuit of boiler only as follows:
REPLACEMENT OF PARTS
●
Close isolating valves on flow and return pipes on
boiler,
see diagram 3.
Note: 1)
These valves are closed when levers are
at right angles to direction of flow.
2)
It is not necessary to drain down entire
heating system to carry out this work.
●
Drain boiler by attaching a plastic tube to drain
outlet and opening drain valve knob anticlockwise,
see
diagram 4.
●
Locate central heating flow thermistor on central
heating flow pipe below automatic air vent
.
●
Remove electrical connections from thermistor.
●
Unscrew and remove thermistor from flow pipe.
●
Fit replacement thermistor in reverse order to remo-
val.
●
Refit electrical connections.
●
Open isolating valves on flow and return connec-
tions, refill, vent and pressurise boiler.
●
Check for leaks.
To replace central heating temperature control
●
Remove two screws from front panel and open
panel
.
●
Carefully pull off central heating temperature con-
trol plug from PCB terminal marked A5.
●
Carefully pull off two leads to ‘Summer/Winter’
switch.
●
Remove central heating temperature adjustment
knob by pushing off with suitable tool through one of
the holes in rear of control panel,
see diagram 6
.
●
Using suitable tool, unscrew and remove nut secu-
ring control to control panel.
●
Fit replacement control in reverse order to remo-
val.
To replace pump
●
Drain down the heating circuit of the boiler only,
as described previously.
Note:
It is not necessary to drain down entire heating
system to carry out this work.
●
Undo two pump union nuts and pull pump
forwards.
Diagram. 6
Diagram. 5
Summary of Contents for SYLVA FF 24 E
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