Baxi 600 System 2 (15, 18, 24)
System boiler, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoNominal and range of tolerance, frontal panel closed (MI 7.4.4 Service settings). The table prints decimal commas and the ÷ sign for the range; written here with points and to, as the MI does in 7.4.3 and 7.4.5. 7.4.5 says the NG CO₂ figures are for G20 only: for G20 with up to 20% hydrogen, calibrate the gas valve by O₂ only. 7.4.5 also says to remove the boiler door to take measurements or make adjustments, while the 7.4.4 table is headed Frontal panel closed. | 9.0% (8.8 to 9.4) | 10.3% (10.2 to 10.7) |
CO₂ at low rate More infoHide infoNominal and range of tolerance, frontal panel closed (MI 7.4.4). NG figure is for G20 only (MI 7.4.5). | 8.5% (8.1 to 8.6) | 9.7% (9.2 to 9.8) |
Maximum CO More infoHide infoThe MI gives two different limits. The 7.4.4 Service settings table gives CO max <400 ppm (frontal panel closed). The Fig.52 Combustion procedure flowchart asks Is CO < 350ppm at both maximum and minimum rate, and says turn the appliance off if not. |
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CO/CO₂ ratio More infoHide infoChecked at maximum and minimum rate (Fig.52). MI 10.1: this must be less than 0.004. | < 0.004 | < 0.004 |
O₂ at high rate More infoHide infoNominal and range of tolerance, frontal panel closed (MI 7.4.4). The MI prints the range highest figure first. For G20 with up to 20% hydrogen, calibrate the gas valve by O₂ only. The MI says 20% hydrogen may raise O₂ in the flue gases by 1.5%, and in that case recommends not adjusting the gas valve. | 4.8% (5.2 to 4.1) | 5.2% (5.4 to 4.6) |
O₂ at low rate More infoHide infoNominal and range of tolerance, frontal panel closed (MI 7.4.4). The MI prints the range highest figure first. | 5.7% (6.5 to 5.6) | 6.1% (6.9 to 6.0) |
Working inlet pressure More infoHide infoCheck with the boiler at maximum rate (chimney sweep). NG figures are from Fig.44 Gas meter to valve, which doesn’t state the gas type; the text says at least 18 mbar (NG) or 37 mbar (LPG) at the gas test point on the gas inlet. At the meter: 19–23 mbar (Fig.44). Pressure drop across system pipework ≤ 1 mbar. Nominal supply pressure (Tab.2): G20 20 mbar, G31 37 mbar. No LPG gas valve figure is given. |
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Gas rate at maximum More infoHide infoMeasure with all other appliances and pilot lights off (MI 7.4.1, Tab.23). Same figures as Tab.8 Combustion characteristics (Qmax). |
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Flue integrity More infoHide infoAt the air inlet test point, boiler at maximum rate (Fig.52, MI 10.1). | O₂ ≥ 20.6% CO₂ < 0.2% | O₂ ≥ 20.6% CO₂ < 0.2% |
From 7801992 - 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 15 System (615-2) | 41-884-01 | NG |
| 600 18 System (618-2) | 41-884-02 | NG |
| 600 24 System (624-2) | 41-484-03 | NG |
Source: Baxi 600 System 2 Installation and Service Manual & Boiler Fiche, 7801992 - 03 (4/23).
Sections: 3.1.2 Certifications; 3.1.3 Gas category; 3.2 Technical data (Tab.8 Combustion characteristics); 7.4.1 Check the operational (working gas inlet pressure and gas rate); 7.4.2 Combustion parameters (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 (maintenance combustion check).
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.