Worcester Bosch Greenstar i junior combi (24i junior, 28i junior)
Combi, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFrom the CO/CO₂ settings table in Setting the gas/air ratio, 30. Setting the CO/CO₂ (MI page 54 for the SIT valve, page 55 for the Dungs valve; the two tables are the same), boiler at maximum in service mode. The tables say CO/CO₂ should be measured after 10 minutes. The technical data (MI page 6) 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 35). | 9.8% ± 0.5% | 11.0% ± 0.5% |
CO₂ at low rate More infoHide infoFrom the CO/CO₂ settings table (MI pages 54 and 55), 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% ± 0.5% | 10.5% ± 0.5% |
Maximum CO More infoHide infoFrom Setting the gas/air ratio (MI pages 54 and 55), checked at maximum and at minimum. | less than 200ppm | less than 200ppm |
CO/CO₂ ratio More infoHide infoPrinted under the CO/CO₂ settings tables (MI pages 54 and 55) 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 with the boiler running at maximum in service mode, with all other gas appliances working (MI Commissioning, page 35). The SIT valve page (MI page 54) gives the same minimums. The Dungs valve page (MI page 55) gives only the LPG minimum of 37mb. The general checks on the back cover (MI page 64) 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. |
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Gas rate at maximum More infoHide infoMax. 10 minutes from lighting, natural gas figures for G20 (MI Technical data, page 6). Measure at the gas meter after 10 minutes at maximum (MI Commissioning, page 35). In service mode the boiler runs both the central heating and hot water circuits. The technical data gives a central heating max. rated heat input of 24.62 kW for both sizes, and a hot water max. rated heat input of 24.49 kW (24i junior) and 28.57 kW (28i junior). |
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From 8 716 115 166a (06/2008)
Enter service mode for high and low rate
High rate
- Hold the service button for 10 seconds until it lights. The blue power indicator flashes quickly.
- Turn the central heating temperature control to maximum. The boiler goes to maximum and the blue light shows 5 pulses.
Low rate
- Turn the central heating temperature control to minimum. The boiler goes to minimum and the blue light shows 2 pulses.
- Turn it back to maximum to return to maximum.
Ending the test
- Hold the service button for 2 seconds until it goes out and the blue power indicator stays on (MI 30.2 note says over a second).
- It returns to normal by itself after 15 minutes.
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| Greenstar 24i junior | 47-311-86 | NG |
| Greenstar 28i junior | 47-311-87 | NG |
| Greenstar 24i junior LPG | 47-311-90 | LPG |
| Greenstar 28i junior LPG | 47-311-91 | LPG |
Source: Worcester Greenstar 24i junior/28i junior wall hung RSF gas fired condensing combination boiler installation, commissioning and servicing instructions, 8 716 115 166a (06/2008).
Sections: Cover (GC numbers); Technical data (page 6); Commissioning (page 35); Setting the gas/air ratio, 30. Setting the CO/CO₂ (pages 54 and 55); General checks (back cover, page 64).
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.