Glow-worm 18-30sxi Range - Manual (Page 32)

32 0020008155A
12 Servicing
Diagram 12.6
12402
THROTTLE
OFFSET
ADJUSTMENT
Diagram 12.7
MIN.
MAX.
POTENTIOMETERS
RETAINING LATCHES
12.5 Condensate Drain
The condense drain does not normally need removing during
servicing.
To flush the condense drain carefully pour water into the heat
exchanger and check that water flows freely to drain.
If the condense drain is blocked refer to section 14.27 for
removal.
12.6 Combustion Check
Once the appliance has been re-assembled (apart from the
front and inner casing panels) connect a CO
2
combustion
analyser to the test point on the flue elbow, see diagram 12.1.
IMPORTANT NOTE: Products of combustion will be discharged
when the cap is removed. It is important to replace the cap
immediately.
Turn on the gas service cock, see diagram 7.1.
With the power off and the appliance cold, unclip the controls
fascia and hinge it down to reveal the potentiometers on the rear
of the User interface, see diagram 12.7. Take care not to allow
the fascia to drop down and damage the wiring.
Turn on the electrical supply.
Ensure external controls are calling for heat. The boiler should
fire automatically.
Allow the boiler to fire for a minimum of 60 seconds and then,
using an electrical screwdriver, rotate the service potentiometer
fully clockwise. This will allow the digital display to indicate the
‘flashing’ fan speed on the appliance fascia.
In the fully clockwise position the display should be indicating
the maximum fan speed of the appliance, 57±1 for 30sxi and
41±1 for 18sxi.
Check the CO
2
value, which should be:
18sxi 30sxi 9.1+0.2-0.5 Case Off
30sxi LPG 10.5+0.3-0.7 Case Off
Note that with the inner case front panel fitted the
combustion readings will increase slightly to:
18sxi 30sxi 9.1+0.3-0.5 Case On
30sxi LPG 10.7+0.3-0.7 Case On
If adjustment proves necessary then proceed as follows.
For LPG appliances refer to the begining of commissioning
LPG CONVERSION - 30sxi only.
Any adjustment to the gas valve should only be carried out by
a competent person.
Refer to diagram 12.6.
Adjust the maximum rate CO
2
by rotating the throttle to
9.1+0.2-0.5 in small incrimental adjustments, then wait for the
analyser to reflect the change before continuing to 9.1+0.2-0.5
(anti-clockwise to increase).
Rotate the service potentiometer fully anti-clockwise. Hold it in
this position for about 5 seconds before rotating the service
potentiometer clockwise to the mid-point or 3 o’clock position.
The fan should reduce to 1200 ±100 rpm which will flash ‘12’ on
the digital display.
Check the CO
2
value, which should be 9.1+0.2-0.5.
If adjustment proves necessary then proceed as follows.
Adjustment of the CO
2
at minimum rate is very coarse so
carefully adjust the CO
2
with the offset adjustment to
9.1+0.2-0.5, see diagram 12.6.
Rotate the service potentiometer fully clockwise and recheck
the maximum rate combustion, which should be
9.1+0.2-0.5 ± 0.2%.
SERVICE
POTENTIOMETER
11505
11417
CONTROLS
FASCIA
USER INTERFACE
After checking combustion rotate the service potentiometer
fully anti-clockwise so that the display indicates the water
temperature.
Replace the cap on the test point and refit the control cover rear
panel.