Baxi Combi 24 HE Installation & Service Instructions Manual page 25

9.0 COMMISSIONING
9.2 Checking the Burner Pressure
1. Turn on the gas and electrical supplies to the boiler
and ensure that all external controls are calling for
heat.
2. Set the hot water and central heating temperature
controls to maximum and the selector switch to the
OFF position (Fig. 37).
3. Slacken the pressure test point sealing screw on
the gas valve and connect a pressure gauge (Fig. 38).
4. Disconnect the sensing tube from the gas valve.
5. Turn the selector switch fully anticlockwise against
the spring pressure to the reset position and hold for
2 seconds to reset the boiler.
6. Turn the selector switch to the Cental Heating and
Domestic Hot Water position (
light ( ) will illuminate (Fig. 37).
7. Turn on a hot water tap to give a flow rate of at
least 10 l/min.
8. The pressure should be :-
NG 10.2 mbar
Propane 21.8 mbar
If not, check that the gas supply pressure is correct
(Natural Gas 20mbar, and Propane 37mbar).
9. The pressure can be adjusted if required.
10. To check and set minimum pressure first remove
one of the modulator wires.
Adjusting the Pressure (Fig 39)
11. Remove the plastic protection cap from the
pressure adjustment nuts on the valve.
12. The smaller nut (5mm) adjusts minimum pressure
and the larger nut (8mm) maximum pressure.
13. Using a suitable spanner adjust the relevant nut
until the correct pressure is achieved.
14. Once the pressure has been set turn the boiler off
and disconnect the pressure gauge.
15. Tighten the pressure test screw and refit the
modulator to the valve. Reassemble in reverse order.
Selector Switch
Reset
). The power ON
Fig. 38
Plastic
Protection
Cap
Modulator
Wire
Minimum Rate
Adjustment Nut
Fig. 39
Burner On
Flame Failure
Power On
Central Heating
Temperature Control
Pressure Test Point
Sealing Screw
Gas Valve
Maximum Rate
Adjustment Nut
NOTE: Gas Valve Electrical
Plug/Igniter not shown for clarity.
2
bar
Fig. 37
Hot Water
Temperature Control
25