Worcester Highflow 3.5 OF Installation And Servicing Instructions page 22

Diverter Valve
(i) Open all radiator valves and re-fill the system venting as
necessary. The appliance is fitted with an automatic air
vent on the heat bank.
U)
Check that the system operates satisfactorily.
NOTE: It is possible with some diverter valves to replace the
operating mechanism only, leaving the valve body in-situ.
Consult the diverter valve manufacturers instructions for further
information.
The following components can be replaced if the cabinet
top panel, cabinet fron panel, and control box and facia
are removed. See
16(a),
(b) and (d) preceding.
25. THE AUTOMATIC AIR VENT
(See Fig. 27.)
(a) Drain down the 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 re-fill the system, venting as
necessary.
(e) Check that the system operates satisfactorily.
The following componets can be replaced if the cabinet
top panel, cabinet front panel, lower front panel, inner
casing, combustion chamber cover and control box and
facia are removed. See
16(a),
(b), (d), (e), (f) and (g)
preceding.
26. 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 area without suitable water treatment, then Worcester
Heat Systems Ltd. Service Department should be contacted
who will advise on suitable remedial action.
27. THE HEAT EXCHANGER
(See Figs. 14, 15 and 28.)
(a) Drain down the heating system.
(b) Slacken the wing nuts securing the
I
J' bolts holding the flue
hood until the
I
J' 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 M 5 screws securing the combustion
chamber to the inner casing. See Fig. 12.
22
Fig. 29 Combined Feed
and Vent Pipe
Central Heating
Flow
Fig. 30
Expansion Vessel
Union Connection
to Heat Bank
Schraider
Pressure Valve
ral
Heating
Return
Union Connection Drain Cock
to Expansion Vessel
(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 re-assemble in the reverse
order ensuring that it is corectly seated in its mountings.
Do not forget to fit new washers.
(g) Open all radiator valves and re-fill the system, venting as
necessary. The appliance is fitted with an automatic air
vent on the heat bank. See Fig 27.
(h) Re-assemble the appliance
(i) Check that the appliance and system operates
satisfactorily.