52
SERVICING
isar - Installation and Servicing
77
DRAINING THE BOILER
1. Refer to frame 57.
2. Remove the boiler bottom panel. Refer to Frame 50.
3. Close all the water isolating (CH and DHW) valves on
the piping frame.
4. To drain the central heating circuit, attach a length of
hose to the drain point and open the drain valve.
However it must be noted that some residual water
may be experienced during the replacement of
components.
5. As there is no direct drain for the domestic hot water
circuit, depending on the location of the boiler, opening
the lowest hot water tap may drain this circuit.
However it must be noted that some residual water
will be experienced during replacement of
components.
6. After replacing any component on the boiler, close
the drain valve, remove the hose and open all
system isolating valves (re-pressurise as
appropriate) before proceeding to check operation
of the boiler.
7. Check operation of the boiler. Refer to Frame 57.
78
DIVERTER VALVE MECHANISM REPLACEMENT
1. Refer to Frame 57.
2. Remove the casing front & bottom panel.
Refer to Frames 49 & 50.
3. Drain the boiler. Refer to Frame 77.
4. Remove the 4 screws retaining the rear support
plate and withdraw the plate. Refer to Frame 75.
Note. The M4 screws fit the casing and the self-
tapping screws fit the plastic pump and
valve housings.
5. Remove the valve actuator head. Refer to Frame
67.
6. Remove the 4 Allen screws and remove the valve
mechanism.
7. Fit the new valve mechanism and gasket,
ensuring correct fit over the location pin.
8. Reassemble in reverse order, ensuring correct
location of screws in the support plate and that
tabs on the pump and valve housings engage in
slots.
9. Refill the boiler. Refer to Frame 36.
10. Check operation of the boiler. Refer to
Frame 57.
isolating valve
(shown closed)
Isolating valves
Drain point
Drain valve
nm8457
TO OPEN
Compression
gas cock
nm7546
Valve
mechanism
Allen
screws
Locating
pin hole
Gasket
SERVICING
203319-3.pmd 27/03/2008, 08:1552
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