Replacement Of Parts; Domestic Hot Water Thermostat - Saunier Duval Sylva FF 24 E Servicing Instructions

REPLACEMENT OF PARTS

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:
6
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. 5
Diagram. 6