41
NOTE: After ignition 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.
After a period of 10 minutes, check that the supply inlet
pressure of the boiler is still 20mbar, disconnect the pressure
gauge.
NOTE: 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.
12.5 Check the Gas Inlet Pressure and Gas
Rate
The supply from the governed meter must be of adequate
size to provide a steady inlet working pressure of 20mbar (8in
wg) at the boiler. On completion, test the gas installation for
tightness using the pressure drop method and suitable leak
detection uid, purge as necessary.
NOTE: Due to the modulating operation of the boiler and
the need to check the gas inlet pressure and measure the
gas rate at maximum rate, it will be necessary to force it to
maximum.
Press the “reset” button on the controls fascia, release
and immediately press and hold in the “+” button. After
approximately 5 seconds “Hi” will be displayed. Pressing
the mode button when “Hi” is selected will force the boiler
to maximum rate, the display will ash between “Hi” and the
“default display” this will indicate the boiler has been forced to
maximum.
12 Commissioning
MODE
MODE
Diagram 12.3
14601
Operational Gas Inlet Pressure
With ALL other gas appliances operating, check the
operational supply pressure at the gas service isolation valve
test point, see diagram 12.2.
The nominal supply pressure for Natural Gas (G20) is 20mbar.
Turn the taps and appliances off, then disconnect the pressure
gauge.
Additionally the safe nominal maximum heat input of the
appliance can be achieved at an inlet pressure down to
15mbar.
NOTE:
The BURNER PRESSURE cannot be measured and
is not used to measure the gas rate.
Gas Rate
Make sure that ALL other gas burning appliances and pilot
lights are off.
Check the gas rate using the gas meter test dial and stop
watch, at least 10 minutes after the burner has lit, see table
below for approximate rates.
In communal installations where the gas rate cannot be
measured it is acceptable to measure the combustion rate as
described in the servicing section.
On completion, press the “mode” and “+” buttons
simultaneously, this will reset the boiler.
18sx : 2.0m3/h (71ft3/h)
30sx : 3.0m3/h (107ft3/h)
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