15.0 Combustion Check
15.1 Checking the CO2
IMPORTANT: The CO2 must be only be checked and adjusted if a suitable calibrated combustion analyser is available.
1. The combustion (CO2) may be checked after running the boiler for several minutes. To do this it is necessary to set the boiler to 'Calibration Mode'.
2. Ensure that all external controls are calling for heat. The actual current boiler temperature is shown on the display.
3. Turn both temperature control knobs fully anticlockwise, then quickly turn the DHW temperature knob ¼ clockwise twice and back fully anticlockwise (Fig. 93).
Fig. 93
4. The display will now alternate between 'SF' and the current boiler temperature and both green LEDs will flash (Figs. 94 & 95).
Fig. 94
Fig. 95
5. Turn the CH temperature knob fully clockwise. As the knob is turned the display will change, indicating the fan speed.
6. The display will show '00', indicating maximum rate, then revert to 'P ' alternating with the current boiler temperature (Figs 96, 97 & 98).
Fig. 96
Fig. 97
Fig. 98
7. Remove the plug from the flue adaptor test point. Insert the analyser probe and allow time for the reading to settle (Fig. 99).
Fig. 99
The CO2 should be 8.7% ± 0.2
8. It is possible to alter the CO2 by adjustment of the gas valve. Remove the plastic cover from the 'Max Rate' adjustment screw. At maximum rate the 'Max. Rate' adjustment screw should be turned, using a suitable hexagon key, until the correct reading is obtained (Fig. 100). Turning clockwise will reduce the CO2. Anticlockwise will increase the CO2.
fig. 100
9. The CO2 must then be checked at minimum rate. Turn the CH temperature knob fully anti-clockwise. As the knob is turned the display will change, indicating the fan speed. When the display reads ' 0' the boiler runs at minimum rate.
The CO2 should be 8.4% ± 0.2.
10. With the boiler on minimum, the 'Min. Rate' adjustment screw must be altered, using a suitable hexagon key, after removing the cap (Fig. 100). Turning anti-clockwise will reduce the CO2. Clockwise will increase the CO2. If the CO2 is reset at either boiler rate it must be rechecked at the other rate and also adjusted if required.
11. The 'Calibration Function' is maintained for 20 minutes unless the maximum CH temperature is exceeded. The function can be disabled at any time by turning the DHW knob.
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