Baxi Checked against MI

Baxi 600 Combi 2 (24, 30, 36)

Combi, natural gas and LPG

Combustion figures

Figure	Natural gas (G20)	LPG (G31)
CO₂ at high rate More infoHide info Nominal, with the range of tolerance in brackets. Front panel closed, boiler in chimney sweep at maximum. Section 7.4.5 says to remove the boiler door to take measurements or make adjustments, while the table in 7.4.4 says front panel closed. On G20 with up to 20% hydrogen, set the gas valve by O₂ only.	9.0% (8.8 to 9.4)	24, 30 10.3% (10.2 to 10.7) 36 10.0% (10.0 to 10.5)
CO₂ at low rate More infoHide info Nominal, with the range of tolerance in brackets. Front panel closed, boiler in chimney sweep at minimum.	8.5% (8.1 to 8.6)	24, 30 9.7% (9.2 to 9.8) 36 9.6% (9.2 to 9.8)
Maximum CO More infoHide info The manual contradicts itself: the service settings table (7.4.4) gives under 400 ppm, but the combustion procedure chart (Fig.52) says CO must be under 350 ppm at maximum and minimum rate, or the appliance must be turned off.	Service settings table <400 ppm Combustion procedure chart <350 ppm	Service settings table <400 ppm Combustion procedure chart <350 ppm
CO/CO₂ ratio More infoHide info At maximum and minimum rate (Fig.52). Section 10.1 also says it must be less than 0.004.	<0.004	<0.004
O₂ at high rate More infoHide info Nominal, with the range of tolerance in brackets. Front panel closed. On G20 with up to 20% hydrogen, O₂ may read up to about 1.5% higher; the manual recommends not adjusting the gas valve then.	4.8% (5.2 to 4.1)	24, 30 5.2% (5.4 to 4.6) 36 5.7% (5.7 to 4.9)
O₂ at low rate More infoHide info Nominal, with the range of tolerance in brackets. Front panel closed.	5.7% (6.5 to 5.6)	24, 30 6.1% (6.9 to 6.0) 36 6.3% (6.9 to 6.0)
Working inlet pressure More infoHide info Check with the boiler at maximum (chimney sweep). At the meter: 19–23 mbar. Fig.44 doesn’t name the gas type; its figures match the text, which says at least 18 mbar (natural gas) or 37 mbar (LPG) at the gas inlet test point (A). Permissible pressure drop across system pipework ≤ 1 mbar. Nominal supply pressure: NG 20 mbar, LPG 37 mbar (Tab.2). LPG gas valve figure not given in MI.	Appliance inlet 18–22 mbar Gas valve test point 17–21 mbar	Appliance inlet at least 37 mbar
Gas rate at maximum More infoHide info Measure with all other appliances and pilot lights off. Tab.9 also gives the minimum: NG 0.52, 0.63, 0.78 m³/h; LPG 0.38, 0.47, 0.58 kg/h.	24 2.61 m³/h 30 3.26 m³/h 36 3.90 m³/h	24 1.92 kg/h 30 2.40 kg/h 36 2.86 kg/h
Flue integrity More infoHide info At the air inlet test point, boiler at maximum, before inserting the probe in the flue gas test point.	O₂ ≥ 20.6% CO₂ < 0.2%	O₂ ≥ 20.6% CO₂ < 0.2%

From 7796561 - 03 (4/23)

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
600 Combi 2 24 (624-2)	47-077-55	NG
600 Combi 2 30 (630-2)	47-077-56	NG
600 Combi 2 36 (636-2)	47-077-57	NG

Source: Baxi 600 Combi 2 (24 - 30 - 36) Installation and Service Manual & Boiler Fiche, 7796561 - 03 (4/23).

Sections: 3.1.2 Certifications (Tab.1); 3.1.3 Gas category (Tab.2); 3.2.1 Technical information (Tab.9); 7.4.1 Checking the working gas inlet pressure and gas rate; 7.4.2 Combustion parameters and chimney sweep function; 7.4.3 LPG conversion procedure; Fig.52 Combustion procedure; 7.4.4 Service settings; 7.4.5 Adjusting the gas valve; 10.1 General.

Spotted something wrong? Tell us.

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.