Worcester 24Si II series Installation And Servicing Instructions Download

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Water Treatment: For optimum performance after

installation, this boiler and its associated central heating system
should be flushed in accordance with the guidelines given in
BS7593: 1992 – Treatment of water in domestic hot water heating
systems. Full instructions are supplied with proprietary cleansers
sold for this purpose. If an inhibitor is to be used after flushing, it
should be used in accordance with the manufacturers instructions.
Remove all system cleanser before adding any inhibitor.
Suitable flushing agents and inhibitors are available from Betz
Dearborn on 0151 4209563 or Fernox on 01799 550811.

12.1 System Set up

Remove  the  cabinet  by  pulling  off  the  clip-on  facia  cover.
Unscrew the two fixing screws, release the sides and lift from the
top location.
Check  that  the  electrical  supply  and  the  gas  supply  to  the
appliance  are  turned  off  and  that  all  the  water  connections
throughout the system are tight.
Open the system valves at the appliance. Refer to Fig 17.
Open all the radiator valves. Remove the automatic air vent cap.
Refer to Fig 37.

Fill the system through an external WRAS approved filling loop
or Worcester Filling Link and Key optional extra, Part N

: 7 716

192 281. Refer to Section 7, Sealed System.
Vent each radiator in turn. The automatic air vent, cap removed,
will vent the appliance. Refer to Fig 37.
It is very imortant that the appliance and system are fully vented
and that all air pockets are removed.
Remove the cap from the pump and turn the shaft about half a
turn. Replace the cap. Refer to Fig 38.

Check that the pressure relief valve operates by turning the knob
anti-clockwise until it releases. Lower the facia to gain access to
the relief valve. Refer to Fig 20. Water should be expelled from
the discharge pipe. Refer also to Fig 54.

The appliance [as despatched] can accommodate a system volume
of 100 litres. Refer to BS7074 Part 1, BS5449 and Table 8. If the
system volume is greater then an extra vessel must be fitted as
close as possible to the appliance central heating return connection
and pressurised to the same figure as the integral vessel.

12.2 Set the Expansion Vessel Pressure

The  charge  pressure  of  the  expansion  vessel  as  dispatched  is
0.5bar,  which  is  equivalent  to  a  static  head  of  5m.  The  charge
pressure  must  not  be  less  than  the  static  head  at  the  point  of
connection.  A  Schraeder  type  valve  is  fitted  to  the

expansion vessel to allow the charge pressure to be increased if
necessary. Refer to Fig 37.
The expansion vessel must be charged to 0.35bar less than the
initial system design pressure.

Note: 1bar = 10.2m of water.

12.3 Set the System Pressure

Fill the system until the pressure gauge is at 2.5bar and check for
leaks.  Release  water  from  the  system  using  the  relief  valve  test
knob  until  the  required  system  pressure  is  obtained,  upto  a
maximum  of  1.5bar.  Set  the  pointer  on  the  pressure  gauge  to
record the set system pressure.
If  the  pressure  indicated  on  the  gauge  is  greater  than  2.65bar
when  operating  at  the  maximum  central  heating  temperature
then an extra expansion vessel must be fitted to the system as
close  as  possible  to  the  appliance  central  heating  return
connection.

12.4 Clock/Programmer

The controls fitted to the appliance should be set up at this
stage. Refer to the instructions sent with the control.

12.5 Checking the Burner Pressure

Check that the gas and electricity supplies are turned off.
Connect pressure gauges to the gas valve to measure the inlet
and burner pressures. Refer to Fig 39.
The appliance is fully set up in the factory and no adjustment
should be necessary.

12. Commissioning The Appliance

Fig. 37. Automatic air vent and combustion

test point

Fig. 38. Pump venting.

Pump

cap

Electrical
connections
cover

Fig. 39. Gas valve.

Automatic air vent

Flue connections

Expansion vessel charg-
ing point

Expansion vessel