Worcester Bosch Checked against MI

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

Floor-standing regular boiler, natural gas and LPG

Combustion figures

Figure	Natural gas (G20)	LPG (G31)
CO₂ at high rate More infoHide info Measured 10 minutes after firing, with the combustion chamber cover on (MI 6.8, Table 13). Table 4 (MI 2.2) gives the same figures without a tolerance.	9.4 ±0.2%	10.8 ±0.2%
CO₂ at low rate More infoHide info Allow about 10 minutes at minimum to settle, with the combustion chamber cover on (MI 6.6, 6.8). Table 4 (MI 2.2) gives the same figures without a tolerance.	30CDi 8.6 ±0.2% 42CDi 9.0 ±0.2%	10.4 ±0.2%
Maximum CO More infoHide info The manual gives two limits. The commissioning flow chart (MI 5.6, Fig. 38) says CO < 350ppm at maximum and minimum rate. Table 13 and the air/gas ratio steps (MI 6.8) say less than 200 ppm, and the flue gas analysis (MI 6.6) says to check readings against Table 13. Both shown as printed.	Commissioning check < 350ppm Air/gas ratio table less than 200 ppm	Commissioning check < 350ppm Air/gas ratio table less than 200 ppm
CO/CO₂ ratio More infoHide info The manual gives two limits. The commissioning flow chart (MI 5.6, Fig. 38) says CO/CO₂ ratio < 0.004. Table 13 (MI 6.8) gives 0.002. Both shown as printed.	Commissioning check < 0.004 Air/gas ratio table 0.002	Commissioning check < 0.004 Air/gas ratio table 0.002
O₂	Not given in MI	Not given in MI
Working inlet pressure More infoHide info At the meter or regulator: NG 19–23, LPG 32–45 mbar. Measure with the boiler at maximum and all other gas appliances working. The drop from meter to gas valve must not be more than 2.5 mbar (NG) or 4 mbar (LPG).	Appliance inlet 18–22 mbar Gas valve test point 16.5–20.5 mbar	Appliance inlet 29.5–42.5 mbar Gas valve test point 28–41 mbar
Gas rate at maximum More infoHide info Measured at the gas meter after 10 minutes at maximum. NG figures assume a CV of 1040 Btu/ft³ (38.76 MJ/m³). At test gas G20 (37.78 MJ/m³): 30CDi 3.27, 42CDi 4.4 m³/h. Where there’s no gas meter (e.g. LPG), check CO/CO₂ instead (MI 5.5.2).	30CDi 3.19 m³/h 42CDi 4.29 m³/h	30CDi 2.3 kg/h 42CDi 3.3 kg/h
Flue integrity More infoHide info At the air inlet sample point, combustion cover on, boiler at maximum.	O₂ ≥ 20.6% CO₂ < 0.2%	O₂ ≥ 20.6% CO₂ < 0.2%

From 6 720 818 079 (2016/04)

Enter service mode for high and low rate

High rate

Hold the Service engineer button (chimney sweep symbol) for 10 seconds. It lights up steady and the blue power light pulses five times.
Turn the temperature control to maximum. The boiler goes to maximum.

Low rate

Turn the temperature control to minimum. The boiler goes to minimum.
Turn the temperature control back to maximum to return to maximum.

Ending the test

Press the Service engineer button again to come out. MI 6.8 says hold it over 1 second in one place and 2 seconds in another.
The blue power light goes back to steady. It also ends by itself after 15 minutes.

Models and GC numbers

Model	GC number	Gas
FS 30CDi ErP Regular	41-406-62	NG
FS 42CDi ErP Regular	41-406-64	NG
FS 30CDi ErP Regular LPG	41-406-63	LPG
FS 42CDi ErP Regular LPG	41-406-65	LPG

Source: Worcester Greenstar FS 30CDi ErP & 42CDi ErP Regular installation, commissioning and servicing instructions, 6 720 818 079 (2016/04).

Sections: Cover (GC numbers); 2.2 Technical data; 5.5 Checking gas inlet pressure; 5.6 CO and combustion check; 6.5 Checking the flue integrity; 6.6 Flue gas analysis; 6.8 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.