10.9.3 Fan Box Slider Adjustment
In order to minimise the possibility of
tar-like deposits forming in the fan box
and flue, it is important to reduce the
opening of the draught stabiliser door to
a minimum.
If, after setting the draught (as
described in section 10.9.2), the gap
between lowest point of the door and
the draught stabiliser opening is more
than 10mm, it will be necessary to use
the fan box slider plate.
Remove the screw from the slider plate
arm. Refer to Figure 10-14. Slowly pull
out the slider plate arm (to open the
slider plate) until the draft stabiliser
door is almost fully closed, i.e. there is
only a gap of around 5mm between the
lowest point of the door and the draught
stabiliser opening.
72
Figure 10-12:
Draught stabiliser arm
Figure 10-13:
Fitting slotted disc weight
10.10 Flue Gas Analysis
Check the %CO
2
in the flue gases at
maximum output as follows:
•
Ensure the burner display is
showing ‘BURNER FIRING 100%’.
•
Remove the screw from the
combustion test point, located
at the left rear corner of the rear
access cover (on the secondary
heat exchanger). Refer to Figure
10-16.
•
Insert the analyser probe a
minimum of 100mm into the test
point.
•
Monitor the %CO
2
for a few
minutes to see the maximum and
minimum values reached.
•
The %CO
2
measured should range
between a maximum of 12% and a
minimum of 10%.
If necessary the %CO
2
may have
to be adjusted to be within these
limits, as follows:
•
Access the ‘INSTAL’ (Installer)
menu in the burner control settings
and go to the ‘SETUP FAN’ sub
menu.
•
Go to the ‘POWER MAXIMUM’
value and adjust the burner fan
speed using buttons 5 and 6 on
the burner control panel. Refer to
Section 9.4.
•
To decrease the %CO
2
– increase
the fan speed using button 6.
Figure 10-14:
Draught stabiliser weights
Check the draught and, if required,
adjust the position of the weight to
achieve a draught within the required
range of 0.1 to 0.15mbar (0.04 and 0.06
in.wg).
It may be necessary to make further
adjustments to both the position of the
slider arm and the draught stabiliser
weight until the correct draught of
between 0.1 to 0.15mbar is achieved
with the minimum opening of the
draught stabiliser door.
Secure the slider arm to the fan box by
re-fitting the screw previously removed
from the slider arm.
Figure 10-16:
Combustion test point
Figure 10-15:
Fan box slider plate
!
NOTE
The combustion test point in the
flue inspection pipe must NOT
be used to monitor and adjust
the %CO2 when commissioning
the Spira boiler. Only use the
combustion test point at the left rear
of the rear access cover (on the
secondary heat exchanger) for this
purpose.
