Baxi Bermuda BBU 15 HE condensing back boiler (BBU 15 HE)
Condensing back boiler unit, natural gas
Combustion figures
| Figure | Natural gas (G20) |
|---|---|
CO₂ at high rate More infoHide infoChecked in Calibration Mode at maximum rate, after running the boiler for several minutes, at the flue sampling point (MI 10.1). Section 7.2 says combustion is factory set and the air/gas ratio valve should not be adjusted at commissioning. | 9.3% ± 0.2 |
CO₂ at low rate More infoHide infoChecked in Calibration Mode at minimum rate (MI 10.1). | 8.2% ± 0.2 |
Maximum CO More infoHide infoFrom the Checking Combustion chart (MI 7.4), at the flue gas test point. |
|
CO/CO₂ ratio More infoHide infoFrom the Checking Combustion chart (MI 7.4). Sections 8.1 and 10.1 also say the ratio must be less than 0.004. |
|
O₂ | Not given in MI |
Working inlet pressure More infoHide infoAt the inlet gas pressure test point on the gas cock, boiler at maximum rate (MI 7.3, Fig. 47). Technical data gives inlet pressure 20 mbar, and fault finding (11.1) gives a preferred minimum gas pressure of 20 mbar. Fault finding chart H gives the natural gas supply pressure as greater than 10–11 mbar. |
|
Gas rate at maximum More infoHide infoTechnical data figure is after 10 minutes (MI 3.1). The commissioning range is measured with all other appliances and pilot lights off (MI 7.3). Technical data also gives 0.54 m³/h at minimum. |
|
Flue integrity More infoHide infoAt the air inlet test point, boiler at maximum rate (MI 7.4). | O₂ ≥ 20.6% CO₂ < 0.2% |
From Comp No 7101615 - 04 (2/14)
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 |
|---|---|---|
| Bermuda BBU 15 HE | 44-075-09 | NG |
Source: Baxi Bermuda BBU 15 HE Condensing Back Boiler Unit Installation & Servicing Instructions, Comp No 7101615 - 04 (2/14).
Sections: 1.1 Description; 3.1 Technical Data; 7.2 Commissioning the Boiler; 7.3 Check the Operational Gas Inlet Pressure; 7.4 Checking Combustion; 8.1 Annual Servicing; 10.1 Setting the Gas Valve (CO2 check); 11.1 Initial Fault Finding Checks; 11.0 Fault Finding chart 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.