Baxi 800 System 2 (18, 24, 30)
System boiler, natural gas and LPG
- LPG supply pressure in Tab.2 (MI section 3.1.3): the characters are lost in the PDF and can’t be read
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFront panel closed, boiler in chimney sweep at maximum. NG values are for G20 only: for G20 with up to 20% hydrogen, use the O₂ values to calibrate the gas valve. Same figures for all three sizes. The MI prints them with decimal commas (9,0%). | 9.0% (8.8 to 9.4) | 10.3% (10.2 to 10.7) |
CO₂ at low rate More infoHide infoFront panel closed, boiler in chimney sweep at minimum. NG values are for G20 only: for G20 with up to 20% hydrogen, use the O₂ values to calibrate the gas valve. | 8.5% (8.1 to 8.6) | 9.7% (9.2 to 9.8) |
Maximum CO More infoHide infoThe MI contradicts itself. The service settings table (MI 7.4.3, p. 49) gives CO max <400 ppm, front panel closed. The combustion procedure flowchart (Fig.52, p. 48) says CO must be under 350 ppm at both maximum and minimum rate. |
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CO/CO₂ ratio More infoHide infoAt 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 infoFront panel closed. The MI prints the tolerance ranges high to low. It says that 20% hydrogen in the gas may raise O₂ in the flue gases by about 1.5%, so use the standard O₂ values for the gas used when adjusting. | 4.8% (5.2 to 4.1) | 5.2% (5.4 to 4.6) |
O₂ at low rate More infoHide infoFront panel closed. The MI prints the tolerance ranges high to low. | 5.7% (6.5 to 5.6) | 6.1% (6.9 to 6.0) |
Working inlet pressure More infoHide infoBoiler at maximum rate. NG figures from Fig.44. At the meter: NG 19–23 mbar. Text in MI 7.4.1 says the working pressure at the gas inlet test point (A) must be at least 18 mbar (NG) or 37 mbar (LPG). Permissible pressure drop across system pipework ≤ 1 mbar. Tab.2 gives NG supply pressure 20 mbar; the LPG figure in Tab.2 can’t be read. |
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Gas rate at maximum More infoHide infoWith any other appliances and pilot lights turned off (MI 7.4.1 Tab.23, same in Tab.8). Gas rate at minimum (Tab.8): NG 0.52 m³/h, LPG 0.38 kg/h, all sizes. |
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Flue integrity More infoHide infoAt the air inlet test point, boiler at maximum rate (Fig.52, section 10.1). | O₂ ≥ 20.6% CO₂ < 0.2% | O₂ ≥ 20.6% CO₂ < 0.2% |
From 7821598 - 03 (4/23)
Enter service mode for high and low rate
High rate
Low rate
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| 800 System 2 18 (818-2) | 41-470-99 | Not stated |
| 800 System 2 24 (824-2) | 41-884-09 | Not stated |
| 800 System 2 30 (830-2) | 41-884-08 | Not stated |
Source: Baxi 800 System 2 Installation and Service Manual & Boiler Fiche, 7821598 - 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 and chimney sweep function; Fig.52 Combustion procedure; 7.4.3 LPG conversion procedure; 7.4.3 Service settings (p. 49); 7.4.4 Adjusting the gas valve (p. 50); 10.1 Maintenance, 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.