Worcester 24CDi BF Installation And Servicing Instructions page 16

Set the gas valve mode switch to the minimum position.
The burner pressure will drop to the minimum setting which
should be 2mbar for natural gas.
Test for gas soundness at the joint between the burner and the gas
valve with leak detection fluid.
NOTE: The burner pressure is factory set and if (after checking that
the supply pressure is sufficient) the correct pressure is not
obtained then Worcester Heat Systems Service Department should
be contacted.
If the appliance does not light, check that it is not in the 'lockout'
state by pressing the lockout reset button. See Fig. 25.
Set the gas valve mode switch back to the normal position and
refit the facia.
Turn off the electricity supply, and then back on again to reset the
controls.
Gradually close the hot tap and check that the burner pressure
drops. Fully open the tap and check that the burner pressure rises.
Fully close the tap and check that the burner goes off. The fan
may continue running until the appliance has cooled to a preset
temperature.
Set the Operating Switch to OFF.
Fig. 22. Pressure relief valve.
Pressure
relief
valve
Fig. 23 Gas Valve
Pull off the three
electrical solenoid
plug connections
Safety solenoid
valves
Fixing screws (2)
Turn knob
anti-clockwise
to test
Sealing washer
Union fitting
Central Heating
Check that all the radiator valves are open. Set the room
thermostat and the Central Heating Temperature Control to
maximum. Set the DHW temperature control to MIN.
On sealed systems check that the system is pressurised and set to
the required pressure as indicated on the gauge.
Set the Programmer, if fitted, to HEATING & WATER.
Set the operating switch to ON.
The burner will light.
The appliance will modulate its output from 9.0 to 24.0 kW over a
period of about two minutes.
Check the system to ensure that all the radiators are heating up
evenly. If not then bleed each radiator through its vent screw.
Shut down all but one of the radiators and observe the burner
pressure fall. Open all of the radiator valves and check that the
burner pressure rises.
Balance the system so that the required temperature difference
across the central heating flow and return pipes is obtained. See
Table 3.
Fig. 24. Central heating by-pass adjustment.
Burner connection
Union fitting
Sealing washer
16
Burner pressure
test point
Start pressure adjustment
screw
Maximum pressure
adjustment screw
Inlet pressure
test point
Fixing screws (2)
Gas valve bracket