Saunier Duval ISOFAST F 28 E Installation And Operating Instructions Manual page 23

REPLACEMENT OF PARTS
To replace pump
• Drain down heating circuit of the boiler only, as
described previously.
Note: It is not necessary to drain down entire heat-
ing system to carry out this work.
• Undo two fixing screws and remove pump retain-
ing bracket from front of pump.
• Undo clips securing pump outlet hose connec-
tion to pump.
• Slide hose along pipe to clear pump outlet.
• Disconnect pump electrical connection from
PCB.
• Transfer automatic air vent to replacement pump
using new washers supplied.
• Re-connect electrical connection to PCB.
• Fit replacement pump in reverse order to re-
moval.
• Open isolating valves on flow and return connec-
tions, refill, vent and pressurise boiler.
• Check for leaks.
To replace domestic hot water heat exchanger
• Drain down heating and hot water circuits of
boiler only as described previously.
Note: It is not necessary to drain down entire heat-
ing system to carry out this work.
• Unscrew and remove cold water inlet pipe from
fixing jig to water flow sensor.
• Supporting domestic heat exchanger, unscrew
and remove two screws securing it onto pump
mounting and 3-way valve/bypass housing.
• Remove heat exchanger from boiler.
• Fit replacement heat exchanger in reverse order
to removal using new seals, supplied.
Note: Heat exchanger mounting screws are offset
to ensure correct fitting of replacement.
To replace 3-way valve head
• Locate 3- way valve in centre of lower controls
area.
• Remove electrical plug from valve head.
• Pull out slotted metal clip from valve body and
remove valve head from body.
• Fit replacement valve head in reverse order to
removal.
Note :
1) When refiting clip, ensure that letters OK are as
shown in diagram 6.
2)It is not necessary to drain boiler to carry out this
work.
To replace 3-way valve/bypass housing
• Drain down heating and hot water circuit of boiler
only as described previously.
Note: It is not necessary to drain down entire heat-
ing system to carry out this work.
• Remove 3-way valve head as described previ-
ously.
• Remove domestic hot water heat exchanger as
described previously.
• Undo pipe connection from 3-way valve/bypass
housing to primary heat exchanger, see diagram 7.
• Pull out slotted metal clips and remove bypass
pipe.
• Pull out slotted metal clip and remove domestic
pipe from 3-way valve/bypass housing to storage
vessel.
• Undo pipe from 3-way valve/bypass housing to
fixing jig.
• From underneath boiler, undo two screws secur-
ing 3-way valve/bypass housing and lift out of
boiler.
• Fit replacement 3-way valve/bypass housing in
reverse order to removal.
To replace system pressure sensor
• Drain down heating circuit of boiler only as de-
scribed previously.
Note: It is not necessary to drain down entire heat-
ing system to carry out this work.
• Locate system pressure sensor at front left hand
side of boiler, see diagram 8.
• Remove electrical connections from sensor.
• Pull off slotted metal clip and remove sensor from
boiler.
• Fit replacement sensor in reverse order to re-
moval.
To replace gas valve module
• Locate gas valve module attached to side of gas
valve.
Diagram 6
Diagram 7
Diagram 8
2 3