Setting The Gas Valve - Baxi 47 075 35 Installation & Servicing Instructions Manual

Fig. 91, Fig. 91a and Fig. 92
page 48
15.0 Setting the Gas Valve
15.1 Setting the Gas Valve (CO
IMPORTANT: The CO must be only be checked and adjusted to set the valve if a suitable
2
calibrated combustion analyser is available, operated by a competent person ­ see Section 13.1
1. The combustion (CO
'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 control knobs fully anticlockwise, then quickly turn the right hand knob 1/4 clockwise twice and back fully anticlockwise
(Fig. 93).
4. The display will now alternate between 'SF' and the current boiler temperature and both green LEDs will flash (Figs. 94 & 95).
5. Turn the left hand 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).
7. Remove the plug from the flue sampling test point. Insert the analyser probe and allow sufficient time for the reading to settle (Fig.
99).
The CO should be 8.7% ± 0.2
2
8. It is possible to alter the CO2 by adjustment of the gas valve. Remove the plastic cover from the Throttle Adjustment Screw. At
maximum rate the Throttle Adjustment Screw should be turned, using a suitable hexagon key, until the correct reading is obtained
(Fig. 100). Turning clockwise will reduce the CO
9. The CO must then be checked at minimum rate. Turn the left hand knob fully anti­clockwise. As the knob is turned the display will
2
change, indicating the fan speed. When the display reads ' 0' the boiler runs at minimum rate.
The CO should be 8.4% ± 0.2
2
10. With the boiler on minimum, the Offset Adjustment Screw must be altered, using a suitable hexagon key, after removing the cap
(Fig. 100). Turning anti­clockwise will reduce the CO
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 right hand knob.
12. Check the Combustion Performance (CO/CO
Fig. 93
Fig. 94
check)
2
) may be checked after running the boiler for several minutes. To do this it is necessary to set the boiler to
2
2
Fig. 95
. Anticlockwise will increase the CO
2
. Clockwise will increase the CO
2
ratio). This must be less than 0.004.
.
2
.
2