Worcester Bosch Greenstar CDi Classic ErP system (30CDi, 35CDi)
System boiler, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFrom Table 33 (MI 6.2), measured 10 minutes after firing, boiler at maximum in performance test mode. The ±0.4% tolerance is for checking an existing appliance. After cleaning or replacing parts, or when adjusting because the reading is outside ±0.4%, the tolerance is ±0.2%. The technical data (MI 2.3, Table 8) gives the same figures without a tolerance. The MI says combustion is factory set and no adjustment is needed if the gas inlet pressure is correct (MI 5.5), and the air/gas ratio valve must not be adjusted during commissioning unless the Worcester help line recommends it (MI 5.6). | 9.6% ±0.4 | 11.5% ±0.4 |
CO₂ at low rate More infoHide infoFrom Table 33 (MI 6.2), with the central heating control turned to minimum while in performance test mode. Same tolerance rules as at high rate. The technical data (MI 2.3, Table 8) gives the same figures without a tolerance. | 9.0% ±0.4 | 10.5% ±0.4 |
Maximum CO More infoHide infoThe manual gives two limits. The combustion check flow chart (MI 5.6, Fig. 53) says CO < 350ppm at maximum and minimum rate. Table 33 (MI 6.2) says less than 200 ppm. The MI doesn’t say which takes priority. |
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CO/CO₂ ratio More infoHide infoThe manual gives two limits. The combustion check flow chart (MI 5.6, Fig. 53) says CO/CO₂ ratio < 0.004 at maximum and minimum rate. Table 33 (MI 6.2) gives 0.002 in brackets after the CO limit: CO - less than 200 ppm (0.002 ratio). |
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O₂ | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoFrom Figs. 51 and 52 (MI 5.5.1), boiler running at maximum in performance test mode, with all other gas appliances working. At the meter: NG 19–23 mbar. At the regulator: LPG 32–45 mbar. The pressure at the boiler must not be less than the meter pressure minus 1 mbar (NG) or minus 2.5 mbar (LPG), and the drop from the meter to the gas valve must be no more than 2.5 mbar (NG) or 4 mbar (LPG). MI 6.2 repeats the 2.5 and 4 mbar limits. |
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Gas rate at maximum More infoHide infoMax. 10 minutes from lighting, NG figures for G20 (MI 2.3, Table 8). Measure at the gas meter after 10 minutes at maximum (MI 5.5.2). Where there’s no gas meter (e.g. LPG), check CO/CO₂ against Table 33 instead (MI 6.2). Table 8 gives a max. rated heat input of 30.9 kW (30CDi) and 35.0 kW (35CDi). With the optional diverter valve fitted, performance test mode runs the central heating circuits only (MI 5.5). |
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Flue integrity More infoHide infoAt the air inlet sample point on the flue turret, boiler case on, boiler running at maximum, readings allowed to stabilise (MI 6.1.1). Readings outside these limits mean a problem with the flue system or combustion circuit, e.g. missing or dislodged seals. The combustion check flow chart (MI 5.6, Fig. 53) gives the same limits. | O₂ ≥ 20.6% CO₂ < 0.2% | O₂ ≥ 20.6% CO₂ < 0.2% |
From 6 720 815 724 (2015/05)
Enter service mode for high and low rate
High rate
- Hold the performance test button (chimney sweep symbol) for 10 seconds or more until it lights up.
- Turn the central heating temperature control to maximum. Display shows = = and the flow temperature in turn.
Low rate
- Turn the central heating temperature control to minimum for minimum.
- Turn it back to maximum to go back to maximum.
Ending the test
- Hold the performance test button for 2 seconds (MI 6.2 note says over 1 second). Its light goes out and the blue indicator stays on.
- MI 5.5.2 says press the service button (spanner) instead; the MI differs. It ends by itself after 15 minutes.
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| 30CDi Classic System ErP | 41-406-37 | NG |
| 35CDi Classic System ErP | 41-406-39 | NG |
| 30CDi Classic System ErP LPG | 41-406-38 | LPG |
| 35CDi Classic System ErP LPG | 41-406-40 | LPG |
Source: Greenstar CDi Classic System ErP wall hung RSF gas fired condensing system boiler installation, commissioning and servicing instructions, 6 720 815 724 (2015/05).
Sections: Cover (GC numbers); 2.3 Technical data; 5.5 Commissioning; 5.5.1 Checking the gas inlet pressure; 5.5.2 Checking the gas rate; 5.6 CO and combustion checks; 6.1.1 Checking flue integrity; 6.1.3, Set the boiler to maximum paragraph; 6.2 Setting the air/gas ratio.
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.