Baxi Potterton Condensing Combination Boiler manual Setting the Gas Valve

x 2

Central Heating			Domestic Hot Water
Temperature Control		Fig. 102	Temperature Control
Selector Switch	Display
Reset				2
			1
				3
			0	4
				bar
	Central Heating		Domestic Hot Water
Temperature Control			Temperature Control

Fig. 103 Fig. 104

Fig. 105 Fig. 106 Fig. 107

Flue Adaptor Test

15.0Setting the Gas Valve

15.1Setting the Gas Valve (CO2 check)

IMPORTANT: The CO2 must be only be checked and adjusted to set the valve if a suitable calibrated combustion analyser is available, operated by a competent person - see Section 13.1

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 control knobs fully anticlockwise, then quickly
turn the right hand knob 1/4 clockwise twice and back fully
anticlockwise (Fig. 102).
4.	The display will now alternate between ‘SF’ and the
current boiler temperature and both green LEDs will flash
(Figs. 103 & 104).
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. 105, 106 & 107).
7.	Remove the plug from the flue sampling test point. Insert
the analyser probe and allow sufficient time for the reading
to settle (Fig. 108).
	The CO2 should be 8.7% ± 0.2

Plug

Point

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

Analyser Probe

Fig. 108

Offset
Adjustment Screw	Throttle
(cap fitted)
	Adjustment Screw
	(cover removed)

Adjustment Screw should be turned, using a suitable

hexagon key, until the correct reading is obtained (Fig. 109).

Turning clockwise will reduce the CO2. Anticlockwise will

increase the CO2.

9. The CO2 must then be checked at minimum rate. Turn

the left hand 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 Offset Adjustment

Screw must be altered, using a suitable hexagon key, after

Reduce CO2	Increase CO2
at min. rate	at min. rate

If the CO2 is reset at minimum rate it must be rechecked at maximum rate again and adjusted if required. If the CO2 is reset at maximum rate it must be rechecked at minimum rate and adjusted if required.

	Reduce CO2	Increase CO2
	at max. rate	at max. rate
Gas Valve	Fig. 109

Do not turn the adjustment screws more than 1/8 of a turn at a time. Allow the analyser reading to settle before any further adjustment

removing the cap (Fig. 109). Turning anti-clockwise will

reduce the CO2. Clockwise will increase the CO2.

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/CO2 ratio).

This must be less than 0.004.

48© Baxi Heating UK Ltd 2012