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Worcester Bosch Checked against MI

Worcester Bosch Greenstar FS CDi Regular (FS 30CDi, FS 42CDi)

Floor-standing regular boiler, natural gas and LPG

Combustion figures

FigureNatural gas (G20)LPG (G31)
CO₂ at high rate
More infoHide infoFrom the CO₂ setting tables in Setting the air/gas ratio (MI page 42), boiler at maximum output (boost button held for 10 seconds, temperature control at maximum). CO₂ should be measured 10 minutes after firing the boiler. Same for both sizes. The technical data (MI page 4) 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 page 30).
9.4 ±0.5%10.8 ±0.5%
CO₂ at low rate
More infoHide infoFrom the CO₂ setting tables (MI page 42), temperature control turned to minimum. The technical data gives the same figures without a tolerance.
FS 30CDi
8.6 ±0.5%
FS 42CDi
9.0 ±0.5%
10.4 ±0.5%
Maximum CO
More infoHide infoFrom Setting the air/gas ratio (MI page 42), checked at maximum and at minimum.
less than 200ppmless than 200ppm
CO/CO₂ ratio
Not given in MINot given in MI
O₂
Not given in MINot given in MI
Working inlet pressure
More infoHide infoMeasured at the gas valve inlet point with the boiler running at maximum, with all other gas appliances working (MI Starting the appliance, page 30). Setting the air/gas ratio (MI page 42) gives the same ranges. The technical data (MI page 4) gives a gas supply pressure of 20 mb (NG) and 37 mb (LPG) without saying where it’s measured.
Gas valve test point
17–19 mbar (18 mbar nominal)
Gas valve test point
35–39 mbar (37 mbar nominal)
Gas rate at maximum
More infoHide infoMax. 10 minutes from lighting, natural gas figures for G20 (MI Technical data, page 4). Measure at the gas meter after 10 minutes at maximum (MI Starting the appliance, page 30). On LPG, where there’s no gas meter, the MI says to check the CO/CO₂ to the figures in Setting the air/gas ratio instead. The technical data gives a max. rated heat input of 30.9 kW (FS 30CDi) and 42 kW (FS 42CDi).
FS 30CDi
3.27 m³/h
FS 42CDi
4.4 m³/h
FS 30CDi
2.3 kg/h
FS 42CDi
3.3 kg/h

From 8 716 115 216b (09.2008)

Enter service mode for high and low rate

High rate

  1. Hold the boost button (chimney sweep symbol, below the spanner button) for 10 seconds. The boost button lights and stays lit.
  2. Turn the temperature control to maximum. The boiler goes to maximum.

Low rate

  1. Turn the temperature control to minimum. The boiler goes to minimum.
  2. Turn it back to maximum to return to maximum.
Ending the test
  • Hold the boost button for 2 seconds. Blue power light stays on steady when back to normal. It also ends by itself after 15 minutes.

Models and GC numbers

ModelGC numberGas
Greenstar FS 30CDi Regular41-406-03NG
Greenstar FS 42CDi Regular41-406-04NG
Greenstar FS 30CDi Regular LPG41-406-05LPG
Greenstar FS 42CDi Regular LPG41-406-06LPG

Source: Worcester Greenstar FS 30CDi & FS 42CDi Regular floor standing RSF gas-fired condensing regular boiler installation, commissioning and servicing instructions, 8 716 115 216b (09.2008).

Sections: Cover (GC numbers); Technical data (page 4); Starting the appliance (page 30); Setting the air/gas ratio (page 42).

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.