Baxi Checked against MI

Baxi Duo-tec 2 Combi GA (24 GA, 28 GA, 33 GA, 40 GA)

Combi, natural gas and LPG

Combustion figures

Figure	Natural gas (G20)	LPG (G31)
CO₂ at high rate More infoHide info MI 14.1 gives one figure for all 3 fan speeds: ‘100’ (maximum), the Ignition Phase speed and ‘00’ (minimum). Combustion is factory set; MI 10.1 says no measurement of the combustion is needed at commissioning and not to adjust the air/gas ratio valve.	9.0% ± 0.7	10.5% ± 1.0
CO₂ at low rate More infoHide info Same figure as high rate (MI 14.1, all 3 fan speeds).	9.0% ± 0.7	10.5% ± 1.0
Maximum CO More infoHide info At maximum and minimum rate (MI 10.2 commissioning flow chart). Not split by gas type.	< 350 ppm	< 350 ppm
CO/CO₂ ratio More infoHide info At maximum and minimum rate (MI 10.2 flow chart; MI 12.1 also says less than 0.004). Not split by gas type.	< 0.004	< 0.004
O₂	Not given in MI	Not given in MI
Working inlet pressure More infoHide info MI 10.3 gives one figure for the inlet test point on the gas cock or the gas valve, at maximum rate: ‘AT LEAST 17mb ! (LPG - 37mb)’. Fault finding (MI 17.0, G) says at the gas valve: NG minimum 17 mbar, Propane minimum 37 mbar. Technical data (MI 4.1) gives nominal inlet pressure NG 20 mbar, Propane 37 mbar, point not stated. Initial fault finding checks (MI 17.1) say the preferred minimum gas pressure is 20 mbar (NG), 37 mbar (LPG).	Appliance inlet At least 17 mbar Gas valve test point At least 17 mbar	Appliance inlet At least 37 mbar Gas valve test point At least 37 mbar
Gas rate at maximum More infoHide info After 10 minutes (MI 4.1). Same figures in MI 10.3, measured with other appliances and pilots off.	24 GA 2.54 m³/h 28 GA 2.96 m³/h 33 GA 3.49 m³/h 40 GA 4.23 m³/h	24 GA 1.92 kg/h 28 GA 2.25 kg/h 33 GA 2.64 kg/h 40 GA 3.2 kg/h
Flue integrity More infoHide info At the air inlet test point, boiler at maximum rate (MI 10.2 flow chart).	O₂ ≥ 20.6% CO₂ < 0.2%	O₂ ≥ 20.6% CO₂ < 0.2%

From Comp No. 7206334 - 09 (9/14)

Enter service mode for high and low rate

High rate

Steps not added yet. Follow the MI.

Low rate

Steps not added yet. Follow the MI.

Ending the test: follow the MI.

Models and GC numbers

Model	GC number	Gas
Duo-tec 2 Combi 24 GA	47-075-54	Not stated
Duo-tec 2 Combi 28 GA	47-075-55	Not stated
Duo-tec 2 Combi 33 GA	47-075-56	Not stated
Duo-tec 2 Combi 40 GA	47-075-57	Not stated

Source: Baxi Duo-tec 2 Combi GA Range Installation & Servicing Instructions, Comp No. 7206334 - 09 (9/14).

Sections: 4.1 Technical data; 10.1 Commissioning the boiler; 10.2 Checking the combustion - Chimney Sweep function; 10.3 Check the operational (working) gas inlet pressure & gas rate; 12.1 Performance safety check & annual servicing; 14.1 Checking the combustion; 14.2 Calibration function; 14.3 Adjusting the CO2; 17.0 Fault finding (G).

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Check these figures against the MI for the appliance in front of you, matched by GC number and manual date. Combustion work needs a calibrated analyser and a Gas Safe registered engineer.