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Baxi Checked against MI

Baxi Assure 500 Combi 2 (Assure 524-2, Assure 530-2, Assure 536-2)

Combi, natural gas and LPG

Combustion figures

FigureNatural gas (G20)LPG (G31)
CO₂ at high rate
More infoHide infoNG: chimney sweep high mode H; MI says remove the boiler door to take measurements or make adjustments (MI 7.2.6). NG values are for G20 only: for G20 + 20% H₂ the MI says to calibrate by O₂%, but it gives no NG O₂ figures. LPG: nominal and range of tolerance, frontal panel closed (MI 7.2.4).
8.8 to 9.4%
24 Combi, 30 Combi
10.3% (10.2 to 10.7)
36 Combi
10.0% (10.0 to 10.5)
CO₂ at low rate
More infoHide infoNG: chimney sweep low mode L, G20 only (MI 7.2.6). LPG: frontal panel closed (MI 7.2.4).
8.1 to 8.6%
24 Combi, 30 Combi
9.7% (9.2 to 9.8)
36 Combi
9.6% (9.2 to 9.8)
Maximum CO
More infoHide infoAt maximum and minimum rate (MI 7.2.5).
< 350 ppm< 350 ppm
CO/CO₂ ratio
More infoHide infoAt maximum and minimum rate (MI 7.2.5, 10.1).
< 0.004< 0.004
O₂ at high rate
More infoHide infoLPG figures copied as printed (MI 7.2.4, frontal panel closed). The printed ranges look odd: the 36 Combi nominal sits at the end of its range.
Not given in MI
24 Combi, 30 Combi
5.2% (5.4 to 4.6)
36 Combi
5.7% (5.7 to 4.9)
O₂ at low rate
More infoHide infoLPG figures copied as printed (MI 7.2.4, frontal panel closed).
Not given in MI
24 Combi, 30 Combi
6.1% (6.9 to 6.0)
36 Combi
6.3% (6.9 to 6.0)
Working inlet pressure
More infoHide infoBoiler at maximum rate (chimney sweep). MI text says at least 17.5 mbar NG or 29.5 mbar LPG at the inlet gas pressure test point. At the meter: NG 18.5–23 mbar. At the LPG storage vessel: 32–45 mbar. Supply pressure in the gas category table: NG 20 mbar, LPG 37 mbar (MI 3.1.3).
Appliance inlet
17.5–22 mbar
Gas valve test point
16.5–21 mbar
Appliance inlet
29.5–42.5 mbar
Gas valve test point
28–41 mbar
Gas rate at maximum
More infoHide infoWith other appliances and pilot lights off (MI 7.2.1). The technical data (MI 3.1.5) gives the same figures.
24 Combi
2.61 m³/h
30 Combi
3.26 m³/h
36 Combi
3.90 m³/h
24 Combi
1.92 kg/h
30 Combi
2.40 kg/h
36 Combi
2.86 kg/h
Flue integrity
More infoHide infoAt the air inlet test point, boiler at maximum rate (MI 7.2.5, 10.1).
O₂ ≥ 20.6%
CO₂ < 0.2%
O₂ ≥ 20.6%
CO₂ < 0.2%

From 7875578-02 (07/24)

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

ModelGC numberGas
Assure 524-2 (24 Combi)47-077-59NG
Assure 530-2 (30 Combi)47-077-60NG
Assure 536-2 (36 Combi)47-077-61NG

Source: Baxi 400 Combi 2.1, 600 Combi 2, 800 Combi 2, Assure 500 Combi 2 Installation and Service Manual &amp; Boiler Fiche, 7875578-02 (07/24).

Sections: 3.1.2 Certifications; 3.1.3 Gas category; 3.1.5 Technical information; 7.2.1 Checking the working gas inlet pressure and gas rate; 7.2.2 Combustion parameters; 7.2.3 Activating the chimney sweep mode; 7.2.4 LPG conversion procedure; 7.2.5 Commissioning procedure; 7.2.6 Adjusting the gas valve; 10.1 General; 11.6.13 Setting an uncalibrated gas valve.

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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.