23
REPLACEMENT OF PARTS
To replace safety valve
• Drain down entire heating system.
• From below boiler, disconnect heating flow pipe
from rear of fixing jig.
• Undo heating flow connection on front of fixing
jig. Remove clip from heating flow pipe connec-
tion on right of front section of reversing valve. Pull
pipe towards right and out of reversing valve. Re-
move pipe from boiler and keep.
• From below boiler, disconnect safety valve dis-
charge pipe.
• Working through boiler from the front using a long
screwdriver, undo and remove screw holding safety
valve assembly to fixing jig.
• Remove complete safety valve assembly from
fixing jig and remove from boiler.
• Fit replacement safety valve in reverse order to
removal.
Note:
Apply silicone grease to 'O' ring before fixing
pipe into right hand side of reversing valve.
• Refill heating system and boiler, vent and pres-
surise as described previously.
To replace heat exchanger
• Drain down both heating and hot water circuits
of boiler only as described previously.
Note:
It is not necessary to drain entire heating sys-
tem to carry out this work.
• Remove combustion chamber cover as de-
scribed in
'Routine Cleaning and Inspection'.
• Remove two clips from heating connections to
left side of heat exchanger.
• Remove clip holding pump outlet connection
into pump and slide connection up pump outlet
pipe. Pull complete pipe down to disengage from
heat exchanger.
• Remove retaining clip from LHS pipe connection
on front section of valve and disengage pipe.
• Disengage pipe downwards from heat ex-
changer.
• Unscrew and disconnect two hot water connec-
tions to right side of heat exchanger.
• Grasp both sides of heat exchanger and slide
forwards and out of boiler.
• Fit replacement heat exchanger in reverse or-
der to removal.
Note:
Use new sealing washers and 'O' rings pro-
vided.
• Open isolating valves on flow and return con-
nections, refill, vent and pressurise boiler. Check for
leaks.
To replace expansion vessel
1 Boiler in place
Note:
The expansion vessel can be replaced with
the boiler in place provided that there is a mini-
mum clearance of 400mm on one side of the boiler
and that no vertical pipework passes between
boiler and wall on that side.
• Drain down the heating circuit of the boiler only
as described in
'To replace pump'.
Note:
It is not necessary to drain entire heating sys-
tem to carry out this work.
• Remove pump from boiler as described previ-
ously.
• Unscrew pipe connection nut from expansion
vessel and disengage pipe from connection. Keep
sealing washer.
• Whilst supporting weight of vessel, push bottom
of vessel away from boiler, disengaging threaded
connection from hole in rear of boiler. Allow vessel
to drop out of its two upper retaining brackets.
• Remove vessel to side of boiler.
• Fit replacement expansion vessel in reverse or-
der to removal ensuring that sealing washer is fit-
ted to vessel pipe connection.
• Check that vessel charge pressure is 1bar. Cor-
rect if necessary.
• Open isolating valves on flow and return con-
nections, refill, vent and pressurise boiler. Check for
leaks.
2 Boiler removed from wall
• Drain down the heating circuit of the boiler only
as described in
'To replace pump'.
Note:
It is not necessary to drain entire heating sys-
tem to carry out this work.
• Ensure that gas and electrical supplies to boiler
are turned off.
• Disconnect flue from either rear or top of boiler
as applicable.
• Disconnect external controls connections, if ap-
plicable.
• Unscrew and disconnect five connections be-
tween fixing jig and boiler.
• Disengage pipe connections. Lift boiler off hang-
ing bracket and place on a convenient working
surface.
• Remove expansion vessel from boiler as de-
scribed in previous section.
• Fit replacement vessel in reverse order to removal
and check charge pressure.
• Replace boiler on wall, tighten all connections,
gas connection first, ensuring that all sealing wash-
ers, filters and the cold water flow regulator are fit-
ted before tightening.
• Reconnect flue system.
• Open isolating valves on flow and return con-
nections, refill, vent and pressurise boiler. Check for
leaks.
• Reconnect external controls connections, if ap-
plicable.
• Reconnect gas and electrical supplies to boiler.
• Check for gas soundness.
To replace boiler thermistor
• Locate boiler thermistor on heating flow pipe on
left hand side of boiler,
see diagram 37.
Diagram 37
Содержание THEMA F 23 E
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