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31 . THE AUTOMATIC AIR VENT
Fig. 29
(a)
Drain down the central heating and domestic hot water
systems.
(b) Unscrew the automatic air vent.
(c)
Fit the replacement air vent using an approved jointing
compound.
(d) Open all radiator valves and refill the system, venting as
necessary.
(e)
Check that the system operates satisfactorily.
32. THE HEAT BANK
Should the heat bank fail or the domestic hot water heat
exchanger within it become scaled up due to its use in a hard
water areas without suitable water treatment, then Worcester
Heat Systems Ltd. Service Department should be contacted,
who will advise on suitable remedial action.
33. THE HEAT EXCHANGER
Figs. 16 and 26.
(a)
Drain down the heating system.
(b) Slacken the wing nuts securing the
T
bolts holding the flue
hood until the
T
sections can be manipulated to pass upwards
through their location brackets.
(c)
Lift the flue hood clear of the heat exchanger and remove from
the casing. Gently prise upwards at the front sides to disengage
if necessary. Take care not to disturb the limit thermostat
connections.
(d) Slacken the two
MS
screws securing the combustion chamber
to the inner casing. See Fig. 26.
(e)
Release the two heat exchanger union connections. Ease back
the pipe work and remove the heat exchanger by lifting it
slightly to release it from the rear mountings.
(f)
Fit a new heat exchanger and reassemble in the reverse order,
ensuring that it is correctly seated in its mountings. Do not
forget to fit new washers.
(g)
Open all radiator valves and refill the system, venting as
necessary. The appliance is fitted with an automatic air vent on
the heat bank. See Fig. 29.
(h)
Reassemble the appliance.
(j)
Check that the appliance and system operates satisfactorily.
26
34. THE DHW HIGH LIMIT THERMOSTAT
Fig. 29
(a) Remove the clip from the end of the overheat thermostat
phial pocket.
(b) Remove the thermostat phial from its pocket and feed it out
of the exposed hole at the left-hand side of the electrical box.
(c)
Pull off the two electrical connectors at the thermostat.
Polarity is not important.
(d) Remove the thermostat centre post fixing nut situated under
the control panel. Ease the thermostctt out of its hole.
(e)
Replace with a new thermostat in reverse order, ensuring the
split pin is replaced and any surplus capillary tube is coiled
neatly OUTSIDE the control panel in the space below the
control panel.
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