Bosch Worcester 15SBi Installation And Servicing Instructions page 20

an extra expansion vessel must be fitted to the system as close
as possible to the appliance in the central heating return
connection.
The appliance [as despatched] can accommodate a system
volume of about 90 litres. Refer to BS7074 Part 1, BS5449 and
Table 9. If the system volume is greater then an extra vessel
must be fitted as close as possible to the appliance in the central
heating return connection and pressurised to the same figure as
the integral vessel.
12.4 Clock/Programmer: The controls fitted to the appliance
should be set up at this stage.
12.5 Check that the gas and electricity supplies are turned off.
Refer to Fig. 16.
Connect a pressure gauge to the gas valve. Refer to Fig. 39.
12.6 Checking the Burner Pressure
Set the temperature control knob to maximum and the
clock/programmer to operate continuously.
Turn on the gas and electricity supplies. A continuous spark will
occur until the burner is alight and sensed by the control circuit.
The burner will light and ramp up to the factory set pressure. If
the burner does not light then press the 'lock-out' reset button.
Refer to Fig 40. Note: The burner pressure is factory set at the
mid point of the range of the boiler and may be reset to match
the system requirements. If, after checking that the supply
pressure is sufficient i.e. 18.0mb approx [NG] or 35mb approx
[Propane] at the gas valve inlet pressure test point, the required
pressure cannot be obtained then contact Worcester Heat
Systems Service Department.
Reset the pressure as necessary by adjusting the screw on the
gas valve. Refit the plastic cap and re-seal using the sealing label
Refer to Table 1 and Section 15.4.1. Refer to Fig.38.
Test for gas soundness at the joint between the burner and the
gas valve with leak detection fluid.
12.7 Domestic Hot Water
Check that all external controls are calling for heat and that the
flow pipe to the cylinder is hot after a short period. Check that
the cylinder thermostat, if fitted, is set to about 55°C.
12.8 Central Heating
Check that all the radiators heat up evenly. If necessary carefully vent.
12.9 Balance the system to give a temperature differential of
11°C. An adjustable by-pass is fitted to the appliance.
12.10 Set the room thermostat to minimum and check that the
burner goes out. Reset the room thermostat and the burner will
re-light.
Turn off the gas service cock. The burner will go out but, after a
short pause, the appliance will attempt to restart and spark for
10 seconds and then 'lock-out'. After 60 seconds carefully open
the gas service cock, press the reset button and observe the
burner re-light and follow the normal sequence of operation.
Refer to Fig 16 and 40.
Turn off the gas service cock and the electricity supply to the
appliance.
Drain the system while the appliance is hot.
Refill, vent and re-pressurise the system as described in Section
12.1, adding a suitable proprietary inhibitor. Further information
is available from WHS Technical Information Dept, Telephone
0990 266241.
12.11 Completion of Commissioning
Disconnect the pressure gauge from the gas valve and tighten
the test point screw.
Replace the facia panel covers.
Restart the appliance and check for gas soundness around the
test point screw.
Refit the cabinet casing.
If the appliance is to be passed over to the user immediately
then set the controls to the users requirements.
If the appliance is to be left inoperative in frosty conditions then
set the programmer, if fitted, to continuous and the appliance to
operate at a low temperature under the control of a frost
thermostat, if fitted.
If there is any possibility of the appliance being left totally
unused in freezing conditions then switch off the gas and
electricity and drain the appliance and the system.
Fig. 38. Gas valve - Softlite adjustment.
15SBi
SOFTLITE
SETTINGS
LPG
24SBi
NG
LPG
2.
3.
1. Softlite Adjustment Cover
2. Burner Pressure Test Point
3. Inlet Pressure Test Point
4. Burner Pressure Adjustment Screw
5. Plastic Cap
Fig. 39. Gas Valve.
8
7
6
1. Gas Valve Outlet
2. Gas Valve
3. Pressure Adjustment
4. Solenoids
5. Gas valve Inlet
6. Inlet Pressure Test Point
7. Burner Pressure Test Point
8. Softlite Adjustment Point
20
ADJUSTER
SEALING LABEL
NG
LPG
G31 G20
LPG NG
G31 G20
NG
1
4
1.
5.
4.
2
3
5