Worcester Bosch Greenstar i System (12i, 24i)
System boiler, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFrom the CO₂ settings table in Setting the gas/air ratio (MI page 52 for the Prettl CE427 valve, page 53 for the SIT valve, page 54 for the Dungs valve; the three tables are the same), boiler at maximum in service mode. The tables say CO₂ should be measured after 10 minutes. The technical data (MI page 5) gives the same figures without a tolerance, for both sizes, but says after 30 mins. The MI says combustion is factory set and no adjustment is needed if the gas inlet pressure is correct (MI page 33). | 9.8% ± 0.2% | 11.0% ± 0.2% |
CO₂ at low rate More infoHide infoFrom the CO₂ settings table (MI pages 52 to 54), central heating control set to minimum while in service mode. The technical data gives the same figures without a tolerance, after 30 mins. | 9.2% ± 0.2% | 10.5% ± 0.2% |
Maximum CO More infoHide infoFrom Setting the gas/air ratio (MI pages 52 to 54), checked at maximum. | less than 200ppm | less than 200ppm |
CO/CO₂ ratio More infoHide infoPrinted under the CO₂ settings tables (MI pages 52 to 54) with the CO limit: CO - less than 200ppm (0.002 ratio). | 0.002 | 0.002 |
O₂ | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoMeasured at the gas valve inlet point (inlet test nipple) with the boiler running at maximum in service mode, with all other gas appliances working (MI Commissioning, page 33). Setting the gas/air ratio (MI pages 52 to 54) says no less than 18.5mb NG or 37mb for LPG. The general checks on the back cover ask whether the incoming gas pressure is at least 18mbar with the boiler at maximum output, without saying where it’s measured; that’s lower than the 18.5 mbar natural gas minimum above. The MI gives no appliance inlet or meter figure. |
|
|
Gas rate at maximum More infoHide infoMax. 10 minutes from lighting, natural gas figures for G20 (MI Technical data, page 5). Measure at the gas meter after 10 minutes at maximum (MI Commissioning, page 33). The technical data gives a central heating max. rated heat input of 12.32 kW (12i System) and 24.62 kW (24i System), for both gases. The 12i System LPG figure of 0.46 kg/h is shown as printed. |
|
|
From 8 716 112 055a (04/06)
Enter service mode for high and low rate
High rate
- Hold the service button (spanner symbol) for 10 seconds. It lights up and the blue power light flashes quickly.
- Turn the central heating temperature control to max. The boiler goes to maximum (blue light gives 5 pulses).
Low rate
- Turn the central heating temperature control to minimum (blue light gives 2 pulses).
- Turn it back to max to go back to maximum.
Ending the test
- Hold the service button for 2 seconds. Its light goes out and the blue light stays on.
- It also ends by itself after 15 minutes.
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| Greenstar 12i System | 41-311-67 | NG |
| Greenstar 24i System | 41-311-68 | NG |
| Greenstar 12i System LPG | 41-311-69 | LPG |
| Greenstar 24i System LPG | 41-311-70 | LPG |
Source: Worcester Greenstar 12i System/24i System wall hung RSF gas-fired condensing boiler installation, commissioning and servicing instructions, 8 716 112 055a (04/06).
Sections: Cover (GC numbers); Technical data (page 5); Commissioning (page 33); Setting the gas/air ratio, 29. and 33. Setting the CO₂ (pages 52, 53 and 54); General checks (back cover).
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.