Worcester Bosch Greenstar i System Compact ErP (27i, 30i)
System boiler, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFrom Tables 28 and 29 (MI 7.6), maximum setting, measured after 10 minutes in chimney sweep mode. The technical data (MI 3.2, Table 4) gives 9.1% (NG) and 10.6% (LPG) at maximum, after 30 minutes. The MI says the gas valve is factory set and must not be adjusted during commissioning if found out of tolerance: call the Worcester help line (MI 6.7). | Between 8.5 and 10.1% | Between 9.8 and 11.1% |
CO₂ at low rate More infoHide infoFrom Tables 28 and 29 (MI 7.6), minimum setting, measured after 10 minutes. The manual contradicts itself: its worked example for NG says that with a maximum reading of 9.5% the minimum must be between 8.0% and 9.3%, but Table 28 only asks for above 7.5%. Both shown as printed. The technical data (MI 3.2, Table 4) gives 8.5% (NG) and 9.6% (LPG) at minimum, after 30 minutes. | A minimum 0.2 lower than the maximum reading taken but above 7.5% | A minimum 0.2 lower than the maximum reading taken but above 8.5% |
Maximum CO More infoHide infoThe manual gives several limits. The combustion check flow chart (MI 6.7, Fig. 57) says CO < 350ppm at maximum and minimum rate. Tables 28 and 29 (MI 7.6) give less than 200ppm at maximum and less than 50ppm at minimum, but the steps beside them in MI 7.6 say to check CO is less than 200ppm at both maximum and minimum. All shown as printed. |
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CO/CO₂ ratio More infoHide infoFrom the combustion check flow chart (MI 6.7, Fig. 57), at maximum and minimum rate. MI 6.5.2 says the technical data gives CO/CO₂ ratios, but Table 4 doesn’t list one, and Tables 28 and 29 (MI 7.6) don’t give one either. | < 0.004 | < 0.004 |
O₂ | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoFrom Figs. 54 and 55 (MI 6.5.1) and the table and Figs. 61 and 62 (MI 7.2), boiler running at maximum in chimney sweep mode. At the meter: NG 19–23 mbar. At the regulator: LPG 32–45 mbar. Allowed drop across the pipework: 1 mbar (NG), 2.5 mbar (LPG); across the boiler: 1.5 mbar. The drop from the meter or regulator to the gas valve must be no more than 2.5 mbar (NG) or 4 mbar (LPG). |
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Gas rate at maximum More infoHide infoMax. 10 minutes from lighting, NG figures for G20 (MI 3.2, Table 4, where the sizes are headed 27kW and 30kW). Measure at the gas meter after at least 10 minutes at maximum output (MI 6.5.2). Where there’s no gas meter (e.g. LPG), check CO/CO₂ instead. |
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Flue integrity More infoHide infoAt the air intake sample point on the flue turret, boiler case on, boiler running at maximum output, readings allowed to stabilise (MI 7.3). Readings outside these limits mean a problem with the flue system or combustion circuit, e.g. missing or dislodged seals. | O₂ ≥ 20.6% CO₂ < 0.2% | O₂ ≥ 20.6% CO₂ < 0.2% |
From 6 720 813 280 (2015/07)
Enter service mode for high and low rate
High rate
- With the control panel in its operating position (not hinged down), hold eco and the spanner/return button together for at least 5 seconds.
- It goes to maximum by itself. Display shows the chimney sweep symbol and Max flashing.
Low rate
- Press ▼ for minimum. Min flashes at the bottom left of the display.
- Press ▲ to go back to maximum. Max flashes.
Ending the test
- Press the spanner/return button to return to normal operation. It also ends by itself after 15 minutes.
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| 27i System Compact ErP | 41-406-58 | NG |
| 30i System Compact ErP | 41-406-60 | NG |
| 27i System Compact ErP LPG | 41-406-59 | LPG |
| 30i System Compact ErP LPG | 41-406-61 | LPG |
Source: Greenstar i System Compact ErP wall hung RSF gas fired condensing system boiler installation, commissioning and servicing instructions, 6 720 813 280 (2015/07).
Sections: Cover (GC numbers); 3.2 Technical data; 6.5 Commissioning; 6.5.1 Checking the gas inlet pressure; 6.5.2 Checking the gas rate; 6.5.3 Gas rating test; 6.7 CO and combustion checks; 7.2 Checking the gas inlet pressure; 7.3 Checking flue integrity; 7.5.1 Setting the boiler to maximum; 7.6 Flue gas analysis.
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.