Worcester Bosch Greenstar CDi combi (25CDi, 30CDi, 37CDi, 42CDi)
Combi, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFrom the CO₂ setting maximum column of the table in Setting the gas/air ratio, step 5.3 (MI page 53), which says CO₂ should be measured 10 minutes after firing the appliance, with the boiler at maximum output in central heating boost mode. The MI doesn’t say whether the case is on or off or where the sample is taken. The technical data (MI page 6) gives the same figures without a tolerance, as CO₂ level at max. rated heat output. The MI says the combustion is factory set and no adjustment is required if the gas inlet pressure is correct (MI Commissioning, page 36, and Finishing commissioning, page 37). It refers to the page 53 procedure after re-assembling the burner (page 42), replacing the gas valve (page 44), reassembly after replacing parts (page 46) and LPG conversion (page 55). |
| 11.5% ± 0.2 |
CO₂ at low rate More infoHide infoFrom the CO₂ setting minimum column of the same table (MI page 53), with the central heating control turned to minimum while in central heating boost mode (steps 5.4 and 5.5). The technical data (MI page 6) gives the same figures without a tolerance, as CO₂ level at min. rated heat output. |
| 10.5% ± 0.2 |
Maximum CO More infoHide infoFrom Setting the gas/air ratio (MI page 53): Check CO is less than 200 ppm, the step straight after setting the CO₂ at maximum. The MI gives one figure for both gases and no separate CO check at minimum. | less than 200 ppm | less than 200 ppm |
CO/CO₂ ratio More infoHide infoThe MI gives no CO/CO₂ ratio, no O₂ figures and no flue integrity (combustion air) check. | Not given in MI | Not given in MI |
O₂ | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoFrom Commissioning, Checking gas inlet pressure (MI page 36): gas supply working pressure at the gas valve inlet point (inlet pressure test point, shown as the inlet test nipple on the gas valve), with the boiler running at maximum in central heating boost mode and all other gas appliances working. Page 36 gives N.G. minimum 18 mbar and L.P.G. 37 mbar. Setting the gas/air ratio (MI page 53) says the inlet pressure, at the inlet pressure point on the gas valve, should be a minimum of 18 mbar for natural gas and 37 mbar for LPG. The MI gives no upper limit and no appliance inlet or meter figure, and says not to continue commissioning until the correct gas inlet pressure is achieved. |
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Gas rate at maximum More infoHide infoGas flow rate, max. 10 minutes from lighting, natural gas figures for G20 and LPG for propane (MI Technical data, page 6). Measure at the gas meter after 10 minutes operation at maximum (MI Commissioning, page 36). The technical data gives a max. rated heat input of 25.8, 30.9, 37.0 and 42.0 kW for hot water and 25.8, 30.9, 30.9 and 30.9 kW for central heating (25CDi, 30CDi, 37CDi, 42CDi, both gases), and doesn’t say which the gas rates are for. |
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From 6 720 613 700a (2006/11)
Enter service mode for high and low rate
High rate
- Press and hold the central heating boost button for 10 seconds until it lights up and stays lit.
- Turn the central heating temperature control to maximum. The boiler goes to maximum.
Low rate
- Turn the central heating temperature control to minimum. The boiler goes to minimum.
- Turn it back to maximum to return to maximum.
- Press and hold the central heating boost button for 2 seconds. The button goes out and the blue power light stays on.
- It also returns to normal by itself after 15 minutes.
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| Greenstar 25CDi | 47-311-92 | NG |
| Greenstar 30CDi | 47-311-93 | NG |
| Greenstar 37CDi | 47-406-08 | NG |
| Greenstar 42CDi | 47-406-10 | NG |
| Greenstar 25CDi LPG | 47-311-96 | LPG |
| Greenstar 30CDi LPG | 47-311-97 | LPG |
| Greenstar 37CDi LPG | 47-406-09 | LPG |
| Greenstar 42CDi LPG | 47-406-11 | LPG |
Source: Worcester Greenstar CDi wall hung RSF gas-fired condensing combination boiler for sealed central heating systems and mains fed domestic hot water instruction manual: installation, commissioning & servicing, 6 720 613 700a (2006/11).
Sections: Cover (GC numbers); Technical data (page 6); Commissioning: Checking gas inlet pressure, Setting the boiler to maximum, Measuring the inlet pressure (page 36); Finishing commissioning (page 37); Inspection and service: Setting boiler to maximum (page 40), To clean the burner and To check the diaphragm in burner cover (page 42); Replacement of parts: 7. Gas valve (page 44), 12. Fan assembly (page 46); Setting the gas/air ratio: 5. Setting the CO₂ (page 53); L.P.G. conversion (page 55).
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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.