21
ROUTINE CLEANING AND INSPECTION
Flue system
• Check externally to make sure that flue is not blocked
• Inspect flue system to make sure that all fittings are
secure.
Operation of fan
• Switch on electrical supply and turn on gas.
• Light burner by opening a hot water tap.
• Without sealed chamber cover in place, burner should
be automatically prevented from lighting by air flow
detection system.
• Refit sealed chamber cover.
• Check that fan operates when burner lights and stops
when it goes out.
Cold water inlet filter
Note:
These valves are closed when slots are at right
angles to direction of flow.
• Drain boiler by opening drain valves (r) and (u), see
diagram 3.
Note:
It is not necessary to drain down entire heating
system to carry out this work.
• Close isolating valve/throttle (m) on cold water iso-
lating cock, see diagram 3.
Note:
This valve is closed when screwed fully clock-
wise.
• Open one or more hot water taps to drain boiler cir-
cuit.
• Disconnect flue system.
• Disconnect boiler pipes onto fixing jig.
• Disconnect mains cable and any external controls ca-
bles.
• Remove boiler from wall.
• From rear of boiler, disconnect domestic pipes from
storage vessel.
• Disconnect electrical connections from vessel.
• Unclip vessel from boiler frame and remove from
boiler.
• Slide off plastic strap and separate two halves of ves-
sel insulation.
• Locate thermistor at top of insulation.
• Replace thermistor in same position as old thermis-
tor.
• Refit vessel in reverse order to removal.
• Refit boiler onto fixing jig, tighten all connections
ensuring that all sealing washers are fitted before tight-
ening.
• Reconnect flue making sure that all joints are prop-
erly connected.
Drain down hot water circuit of boiler only, as fol
lows:
• Close isolating valve/throttle (m) on cold water iso-
lating cock, see diagram 3.
Note:
This valve is closed when screwed fully clock-
wise.
• Open one or more hot water taps to drain boiler cir-
cuit.
• Undo connecting nut from cold water inlet connec-
tion.
• Clean and inspect filter, replace if necessary.
• With both filter and restrictor in place, reconnect con-
necting pipe to inlet connection and tighten.
• Fully open isolating valve/throttle on cold water in-
let and check for leaks.
REPLACEMENT OF PARTS
For replacement of the following components it will be
necessary to remove boiler casing panels as described
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 thermistor
• Locate domestic hot water thermistor on hot water
flow pipe on right hand side of boiler adjacent to gas
valve.
• Unclip thermistor from pipe.
• Disconnect leads from thermistor.
• Fit replacement thermistor.
• Fit leads to replacement thermistor, the polarity is not
important.
To replace central heating thermistor
• Locate central heating thermistor on heating flow pipe
on centre of boiler.
• Unclip thermistor from pipe.
• Disconnect leads from thermistor.
• Fit replacement thermistor.
• Fit leads to replacement thermistor, the polarity is not
important.
To replace storage vessel thermistor
For this operation the boiler must be removed from the
wall.
• Drain down heating and hot water circuit of the boiler
only, as follows:
• Close isolating valves (q) and (v) on central heating
isolating cocks (a) and (c), see diagram 3.
Pla 213
Diagram 3
v
A
B
m
q
D
r
t
G
u
C
F
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