Technical information

Installation and servicing instructions strictly reserved
for qualified gas installers
35
10.4 Initial Lighting
The lighting procedure of the boiler is fully
automated.
Check that all external controls are calling for
heat. If an integral programmer is fitted check
that it is correctly programmed and if necessary
overridden to call for heat.
Ensure that the water temperature control knob
is turned OFF ( ).
Turn on the mains electrical supply and the mains
reset switch to (I) on the controls fascia.
Turn the water temperature control knob to
( ) MINIMUM.
The fan should start and after a few seconds the
ignition will commence
If the burner fails to light the fan will stop. Initially
this may be due to air in the gas supply line. The
boiler will automatically have three attempts at
ignition.
If necessary turn the mains reset switch to the off
position (O), then back to the on position (I) and
the boiler will restart.
After the boiler has lit, allow to warm at
MINIMUM
temperature setting to purge any air from the
system.
NOTE: If the appliance is operated above
MINIMUM on initial lighting, there is a possibility
that the overheat stat will trip, this is due to air in
the system having not been purged. See diagram
10.2 for overheat thermostat/reset switch.
Once the system has been purged of air
turn the central heating knob to the desired
temperature.
The appliance will then continue to fire until the
user controls are satisfied.
NOTE: After first power up the firing sequence
for central heating changes. After one minute
stabilisation time the boiler will ramp slowly to full
rate rather than going immediately to full rate. This
is an adaptive feature to cope with small system
requirements.
10.5 Testing - Gas (Natural Gas only)
Case Off Case On
Burner CO2 (G20) 9.1+0.2-0.5 9.3+0.3-0.5
Burner CO2 10.5+0.3-0.7 10.7+0.3-0.7
Propane (G31)
Should any doubt exist about the gas rate, check
it using the gas meter test dial and stop watch at
least 10 minutes after the burner has lit, making
sure that all other gas burning appliances and
pilot lights are off.
The approximate gas rates:
18 HE : 2.0m3/h (70.6ft3/h)
30 HE : 3.02m3/h (107ft3/h)
The gas valve is factory set for natural gas (G20)
and should need no adjustment. (LPG (G31)
should be adjusted as described on page 30,
(LPG CONVERSION). It should be checked that
the supply pressure is 20mb when the boiler is
firing at full rate. This can be achieved by checking
the inlet pressure at the pressure test point on the
gas valve shown in diagram 10.3.
Disconnect pressure gauge.
NOTE: that the burner pressure cannot be
measured at the gas valve as it is altered by the
suction of the fan and modulated according to
demand.
Replace inner casing panel and casing panel,
see diagram 10.1.
10.6 Testing - Heating System
Check that all remote controls are calling for heat.
The boiler will fire automatically. Fully open all
radiator valves, flow control valve ‘A’ and bypass
valve ‘B’ if fitted, see diagram 4.3.
Balance the radiators as required and if fitted adjust
valve ‘A’ to give the required system differential.
Turn off all radiators that can be shut off by the
user and check to see if less than the maximum
differential allowed of 20°C can be achieved across
flow and return.
Allow the system to reach maximum temperature
then switch off the boiler by isolating from the
electrical supply.