Publication No. 5106226
43
Gas/Air Valve Setup Procedure
7. After 2 minutes, the boiler control will
return to normal operation. Maintain full
central heating demand (or if this is not
possible, draw hot water from a bath tap) to
cause the fan speed to increase to
maximum.
8. Check CO2 content of the flue gas
indicated by combustion analyser.
At maximum fan speed, this should be 9.0
to 9.2% CO2.
For values other than this, use throttle
adjustment screw to obtain correct
setting.
Note:
Turning screw clockwise reduces
CO2; anti-clockwise increases CO2.
Ensure fan does not modulate by
maintaining a CH or DHW demand during
the above sequence.
As a double check, the expected CO
content should be in the range of 65 to 85
ppm when CO2 is 9.1%.
Check that gas rate is approximately 2.55
m3/hr.
9. Replace dust cover,
re-instate air signal
tube between air duct and gas valve
,
checking that tube has not physically
deteriorated or been damaged e.g. cracked.
Carefully replace special sealing screw in
flue gas test point.
