Worcester Bosch Greenstar CDi Compact ErP combi (28CDi, 32CDi, 36CDi)
Combi, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFrom Tables 27 (NG) and 28 (LPG) (MI 7.6), maximum setting, measured after 10 minutes in chimney sweep mode. The tables print the maximum figures without a % sign. The technical data (MI 3.3, Table 5) gives 9.1% (NG) and 10.6% (LPG) at maximum, after 10 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). If CO₂ is still out of tolerance after all the checks in MI 7.6, the gas valve must be replaced. | Between 8.5 and 10.1% | Between 9.8 and 11.1% |
CO₂ at low rate More infoHide infoFrom Tables 27 and 28 (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 27 only asks for above 7.5%. Both shown as printed. The technical data (MI 3.3, Table 5) gives 8.5% (NG) and 9.6% (LPG) at minimum, after 10 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 different limits. The combustion check flow chart (MI 6.7, Fig. 61) says CO < 350ppm at maximum and minimum rate. Tables 27 and 28 (MI 7.6) give less than 200ppm at maximum and less than 50ppm at minimum. All shown as printed. |
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CO/CO₂ ratio More infoHide infoFrom the combustion check flow chart (MI 6.7, Fig. 61), at maximum and minimum rate. MI 6.5.2 says the technical data gives CO/CO₂ ratios, but Table 5 doesn’t list one, and Tables 27 and 28 (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. 58 and 59 (MI 6.5.1) and the table in MI 7.4, 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 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 3.3, Table 5, where the sizes are headed 28kW, 32kW and 36kW). 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. In service mode the boiler runs both the heating and hot water circuits (MI 6.5). Table 5 gives a central heating max. rated heat input of 24.34 kW for every size (hot water: 28.57, 32.65 and 36.7 kW). |
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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 7.2). 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 6 720 813 276 (2015/07)
Enter service mode for high and low rate
High rate
- With the control panel in the operating position, hold eco and the spanner/return button together for at least 5 seconds.
- Chimney sweep symbol shows at the top and Max flashes. It ramps up to maximum by itself.
Low rate
- Press ▼ for minimum. Min flashes.
- Press ▲ to go back to maximum. Max flashes.
Ending the test
- Press ok to come out (MI 6.5). MI 7.6 says press the spanner/return button instead.
- It ends by itself after 15 minutes.
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| 28CDi Compact ErP | 47-406-77 | NG |
| 32CDi Compact ErP | 47-406-79 | NG |
| 36CDi Compact ErP | 47-406-81 | NG |
| 28CDi Compact ErP LPG | 47-406-78 | LPG |
| 32CDi Compact ErP LPG | 47-406-80 | LPG |
| 36CDi Compact ErP LPG | 47-406-82 | LPG |
Source: Greenstar CDi Compact ErP wall hung RSF gas fired condensing combination boiler installation, commissioning and servicing instructions, 6 720 813 276 (2015/07).
Sections: Cover (GC numbers); 3.3 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 flue integrity; 7.4 Checking the gas inlet pressure; 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.