SERVICING
mini HE --- Installation & Servicing 37
50 EXPANSION VESSEL REPLACEMENT
If the CH expansion vessel is faulty, there are 2 options:
A If it has a punctured diaphragm, but is otherwise leak free,
than it can be left in place and a new vessel added to the
return side of the system, external to the boiler, provided it
is of adequate capacity and pre--- charge pressure.
B If there is at least 400 mm (16”) clearance above the
boiler, the expansion vessel can be changed without
removing the boiler (rear exit flues will have to be
disturbed).
For option B, proceed as follows:
1 Disconnect the electrical supply.
2 Gain access to the controls area by removing the boiler
front panel (refer to frame 34).
3 Close off the isolating cocks of the CH circuit at the
bottom of the boiler.
4 Release system pressure by opening the main circuit
drainage cock.
Do not release CH pressure using the pressure relief
valve. It may cause debris within the system to foul
the valve.
5 Completely unscrew the connection A, the locknut B and
remove the expansion vessel from the top of the boiler.
AB
6 Re ---assemble in reverse order.
51 FAN REPLACEMENT
1 Disconnect the electrical supply.
2 Remove outer and inner casing.
3 Disconnect the connectors A and the earth connection B.
4 Disconnect the pipe which connects the venturi device to
the air pressure switch.
5 Unscrew the screw C and remove the fan holder bracket
D.
A
B
C
D
6 Remove the fan by sliding it towards left (see the arrow).
7 Re ---assemble in reverse order.
Note: Always take care when handling the fan, in order to
preserve the balance of the impeller.
To correctly connect the venturi device to the air pressure
switch, refer to the following illustration.
--- +
52 VENTURI REPLACEMENT
1 Remove the fan (see frame 51).
2 Remove and replace the venturi device A by unscrewing
the screw B.
3 Re ---assemble in reverse order.
A
B
SERVICING
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