20
Mynute
7.1
CHECKING APPLIANCE OPERATION
When carrying out any repairs or servicing to the
appliance, the relevant commissioning procedure
must be undertaken to ensure the continued safe
operation of the appliance. Particular attention
should be made to ensure gas soundness, water
soundness, and the electrical integrity of the
appliance.
7.2
APPLIANCE MODE OF OPERATION
When there is a request for heat and/or hot water
via the programmer/time clock and/or any external
control, the pump and fan are started.
NOTE
There must be sufficient system water pressure
(min. 0,5 bar) to ensure the water pressure switch
is activated. If there is insufficient system pressure,
the pump and fan will be prevented from operating.
When the fan runs, it proves the differential air
pressure switch which in-turn allows an ignition
sequence to begin.
NOTE
The ignition sequence lasts approximately 5
seconds, during which the appliance will continue
to spark even if the burner has already lit. If the
spark/sensing electrode does not sense ignition
the appliance will then go to lockout. Ignition is
sensed by the electronic circuitry to ensure flame
stability at the burner. Once successful ignition
has been achieved, the electronic circuitry allows
75% of the full gas rate though the appliance.
After 15 minutes the gas rate is increased to
maximum (100%).
When the appliance reaches the desired
temperature the burner will shut down and the
boiler will perform a three-minute anti-cycle (timer
delay).
NOTE
The timer delay can be de-activated by the
insertion of a “jumper” on the PCB or by isolating
the appliance from the electrical supply for 30
seconds. When the request for heat and/or hot
water has been satisfied, the appliance pump
and/or fan, will continue to circulate to dissipate
any residual heat within the appliance.
7.3
CHECKING AND ADJUSTING BURNER
PRESSURE (see fig. 17)
Altough the burner pressure is factory set, it is
necessary to check it during servicing or if the gas
valve has been removed. Isolate the appliance
from the electrical supply and attach a suitable
manometer to the gas valve outlet test nipple.
Remove the compensator tube (28e only).
7.3.1
SE TTI N G THE MA XI MUM B U RNE R
PRESSURE
Light the boiler as described in 5.6 and compare
the reading on the manometer with the value
described in 2.2. If adjustement is required,
remove the protective cap from the gas valve
modulating coil assembly and turn the outer
SECTION 7 CHECKS, ADJUSTMENTS, AND FAULT FINDING
(10mm) nut clockwise to increase, or counter-
clockwise to decrease the burner pressure.
NOTE
You should ensure that all radiators or heat
emitters are fully open during the above procedure.
This will ensure that the output of the boiler
(burner pressure) is not compromised due to a
high flow temperature.
7.3.2
SETTING THE MINIMUM BURNER PRESSURE
Once the maximum burner pressure has been
checked and/or adjusted, remove one of the grey
wires from the modulating coil. Compare the
reading on the manometer with the value
described in 2.2. If adjustement is required, turn
the inner (red) cross-head screw clockwise to
increase, or counter-clockwise to decrease the
burner pressure, whilst ensuring that the
outer(10mm) nut does not move. When checking
and/or adjustement has been completed, isolate
the appliance from the electrical supply, replace
the protective cap, refit the compensator tube,
refit the grey wire to the modulating coil, remove
the manometer, and tighten the outlet test nipple.
IMPORTANT: A GAS SOUNDNESS CHECK
MUST BE CARRIED OUT.
7.4
COMBUSTION ANALYSIS TEST
A combustion analysis check can easily be caried out
on the appliance via the test points located on the top
of the appliance, however you must check that the
burner pressures are set correctly (see 7.3).
●
Insert the flue gas analyser probe into the right
hand test point (see fig. 25).
●
Locate and remove the protective cap that
conceals the “CO mode” button (see fig. 25A).
●
Light the boiler as described in 5.6 and press
the “CO mode” button once.
●
The boiler will now enter the combustion analysis
mode (CO mode) for a period of 15 minutes.
During this time it will remain on full gas and
“CO” will be displayed on the LED display.
●
Once the flue gas analysis has been made,
press the “CO mode” to resume normal
operation.
Flue gas test point
Fig. 25