Worcester Bosch Greenstar CDi Classic ErP combi (29CDi, 34CDi, 38CDi, 42CDi)
Combi, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFrom Table 13 (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 5) 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). |
| 11.5% ±0.4 |
CO₂ at low rate More infoHide infoFrom Table 13 (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 5) gives the same figures without a tolerance. |
| 10.5% ±0.4 |
Maximum CO More infoHide infoThe manual gives two limits. The combustion check flow chart (MI 5.6, Fig. 56) says CO < 350ppm at maximum and minimum rate. Table 13 and the air/gas ratio steps (MI 6.2) say less than 200 ppm. The MI doesn’t say which takes priority. |
|
|
CO/CO₂ ratio More infoHide infoThe manual gives two limits. The combustion check flow chart (MI 5.6, Fig. 56) says CO/CO₂ ratio < 0.004 at maximum and minimum rate. Table 13 (MI 6.2) gives 0.002 in brackets after the CO limit: CO - less than 200 ppm (0.002 ratio). |
|
|
O₂ | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoFrom Figs. 54 and 55 (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 or regulator to the gas valve must be no more than 2.5 mbar (NG) or 4 mbar (LPG). |
|
|
Gas rate at maximum More infoHide infoMax. 10 minutes from lighting, NG figures for G20 (MI 2.3, Table 5). Measure at the gas meter after 10 minutes at maximum in performance test mode (MI 5.5.2). Where there’s no gas meter (e.g. LPG), check CO/CO₂ against Table 13 instead (MI 6.2). Performance test mode runs the central heating circuit only (MI 5.5), and Table 5 gives a central heating max. rated heat input of 30.9 kW for every size (hot water: 30.9, 35.0, 40.0 and 42.0 kW). |
|
|
Flue integrity More infoHide infoAt the air intake 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. | O₂ ≥ 20.6% CO₂ < 0.2% | O₂ ≥ 20.6% CO₂ < 0.2% |
From 6 720 815 725 (2015/05)
Enter service mode for high and low rate
High rate
- Hold the Performance test button (chimney sweep symbol) for 10 seconds until it lights and stays lit.
- Turn the central heating control (radiator symbol) to max. Boiler goes to maximum.
- Display alternates between three bars on each digit and the flow temperature.
Low rate
- Turn the central heating control to minimum. Boiler goes to minimum.
- Turn it back to max to return to maximum.
Ending the test
- Press and hold the Performance test button for 2 seconds; its light goes out. MI 5.5.1 just says press it again.
- It also ends by itself after 15 minutes.
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| 29CDi Classic ErP | 47-406-65 | NG |
| 34CDi Classic ErP | 47-406-67 | NG |
| 38CDi Classic ErP | 47-406-69 | NG |
| 42CDi Classic ErP | 47-406-71 | NG |
| 29CDi Classic ErP LPG | 47-406-66 | LPG |
| 34CDi Classic ErP LPG | 47-406-68 | LPG |
| 38CDi Classic ErP LPG | 47-406-70 | LPG |
| 42CDi Classic ErP LPG | 47-406-72 | LPG |
Source: Greenstar CDi Classic ErP wall hung RSF gas fired condensing combination boiler installation, commissioning and servicing instructions, 6 720 815 725 (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.