Baxi Baxi 800 System (818, 824)
System boiler, natural gas
Combustion figures
| Figure | Natural gas (G20) |
|---|---|
CO₂ at high rate More infoHide infoCase front panel on (MI Tab.22). With the case front panel off: 8.8% +0.3 −0.2. The Setting the gas valve table (MI 9.3.8) gives 8.8% +0.3 −0.2 at maximum without saying case on or off, which matches the case-off figure. The MI says the case front panel must be fitted when checking combustion (MI 7.4.2). | 9.0% +0.3 −0.2 |
CO₂ at low rate More infoHide infoCase front panel on (MI Tab.22). With the case front panel off: 8.3% +0.1 −0.4. The Setting the gas valve table (MI 9.3.8) gives 8.3% +0.1 −0.4 at minimum without saying case on or off, which matches the case-off figure. | 8.5% +0.1 −0.4 |
Maximum CO More infoHide infoAt both maximum and minimum rate, measured at the flue gas test point (MI Fig.40 Combustion procedure). | <350 ppm |
CO/CO₂ ratio More infoHide infoAt both maximum and minimum rate (MI Fig.40). MI 9.1 and 9.3.8 also say it must be less than 0.004. | <0.004 |
O₂ | Not given in MI |
Working inlet pressure More infoHide infoWith the boiler at maximum rate. At the meter: 19–23 mbar (MI Fig.36). The MI also says the inlet test point (A) must be at least 18 mbar, the permissible pressure drop across system pipework is 1 mbar or less, the minimum at the meter is 19 mbar (MI 10.1.1) and the minimum at the gas valve is 17 mbar (MI 10.2.3). Dynamic (nominal) inlet pressure 20 mbar. |
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Gas rate at maximum More infoHide infoNatural gas (G20) Qmax, with all other appliances and pilot lights off. Qmin is 0.49 m³/h on both sizes (MI Tab.21). |
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Flue integrity More infoHide infoAt the incoming air test point on the flue adaptor, boiler at maximum rate (MI Fig.40 and 9.1). | O₂ ≥ 20.6% CO₂ < 0.2% |
From 7729931-01
Enter service mode for high and low rate
High rate
Low rate
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| 818 System (18) | 41-470-73 | NG |
| 824 System (24) | 41-470-74 | NG |
Source: Baxi System 818 - 824 Installation and Service Manual (High Efficiency Wall Hung Condensing Gas Boiler), 7729931-01.
Sections: 3.1.3 Gas category; 3.2.1 Technical information (Tab.5, Tab.7); 7.4.1 Check the operational (working gas inlet pressure and gas rate); 7.4.2 Checking combustion - chimney sweep mode (Fig.39, Fig.40 Combustion procedure); 9.1 General (Check the Combustion Performance); 9.3.8 Gas valve (Tab.22, Setting the gas valve); 10.1.1 Initial error fault finding checks; 10.2.3 Fault finding solutions sections F to H.
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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.