Worcester Bosch Greenstar i System (12i, 15i, 18i, 24i)
System boiler, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFrom Table 24 CO/CO₂ settings (MI 6.6.1, page 47), CO₂ max., boiler at maximum output in service mode. Table 24 says CO/CO₂ should be measured after 10 minutes, and heads the natural gas rows Natural gas 12i System and Natural gas 15,18 & 24i System. MI 6.5 says to connect the analyser to the flue gas sampling point (Fig. 74), run the boiler at maximum output for at least 10 minutes and check the readings against Table 24. The MI doesn’t say whether the case should be on or off. Table 24 note: when checking an existing appliance the tolerance is ± 0.5; if checking after cleaning or component replacement, or for adjustment when the reading obtained is outside the tolerances given, the tolerance is ± 0.2. The technical data (MI 2.2, Table 6) gives the same figures without a tolerance, but says after 30 min. MI 5.5 says the combustion settings are checked, adjusted and preset at the factory, no measurement of the combustion values is necessary provided there is a meter installed allowing the gas rate to be checked, and not to adjust the air/gas ratio valve; MI 6.6.1 gives the steps for setting it. |
| 11.0% ± 0.5 |
CO₂ at low rate More infoHide infoFrom Table 24 (MI 6.6.1, page 47), CO₂ min., central heating control set to minimum while in service mode. Same 10 minute timing and tolerance note as at high rate. The technical data (MI 2.2, Table 6) gives the same figures without a tolerance, at min. rated heat output, after 30 min. |
| 10.5% ± 0.5 |
Maximum CO More infoHide infoFrom Table 24 (MI 6.6.1, page 47): CO - less than 200 ppm (0.002 ratio). The steps in MI 6.6.1 say to check CO is less than 200ppm at maximum, and again after setting the minimum. | less than 200 ppm | less than 200 ppm |
CO/CO₂ ratio More infoHide infoPrinted in Table 24 (MI 6.6.1, page 47) in brackets after the CO limit: CO - less than 200 ppm (0.002 ratio). The MI gives no other ratio figure. | 0.002 | 0.002 |
O₂ | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoFrom Figs. 62 and 63 (MI 5.5.1, page 40) and the gas pressure table in MI 6.2 (page 44), which give the same figures (boiler inlet and gas control valve). Measured at the inlet pressure test point on the gas valve (Fig. 61) with the boiler running at maximum in service mode, with all other gas appliances working (MI 5.5.1). At the meter: NG 19–23 mbar. At the regulator: LPG 32–45 mbar. Allowed drop across the pipework: 1 mbar (NG), 2.5 mbar (LPG); across the boiler: 1.5 mbar (NG and LPG). The MI 5.5.1 text says the pressure at the boiler must not be less than the pressure read at the meter minus 1 mbar, and the drop from the meter to the gas valve must not be more than 2.5 mbar; the text names only the meter, and for LPG Fig. 63 shows 2.5 mbar to the boiler inlet plus 1.5 mbar across the boiler. |
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Gas rate at maximum More infoHide infoGas flow rate, max. 10 minutes from lighting (MI 2.2, Table 6), natural gas figures for G20, LPG figures for propane. MI 5.5.2 says to measure the gas rate at the gas meter after 10 minutes operation at maximum; where a gas meter is not available (e.g. L.P.G.), the CO/CO₂ must be checked as in Setting the air/gas ratio (MI 6.6) instead. Table 6 gives a maximum rated heat input (net) of 12.32 kW (12i), 15.40 kW (15i), 18.48 kW (18i) and 24.62 kW (24i), the same for both gases. |
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Flue integrity More infoHide infoAt the air inlet sample point on the flue turret (Tab. 23 and Fig. 68; the steps call it the air intake test point), boiler case on, boiler running at maximum, readings allowed to stabilise (MI 6.3, page 44). The MI words it as O₂ is equal to, or greater than 20.6% and CO₂ is less than 0.2%. Readings outside these limits indicate a problem with the flue system or combustion circuit. | O₂ ≥ 20.6% CO₂ < 0.2% | O₂ ≥ 20.6% CO₂ < 0.2% |
From 6 720 644 743a (2010/10)
Enter service mode for high and low rate
High rate
- Hold the service button (spanner symbol) for more than 10 seconds until it lights up.
- Turn the central heating control to max. It goes to maximum and the blue power light pulses 5 times.
Low rate
- Turn the central heating control to minimum. The blue power light pulses 2 times.
- Turn the central heating control back to max to return to maximum.
Ending the test
- Press the service button for more than a second. It 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 12i System | 41-311-67 | NG |
| Greenstar 15i System | 41-311-84 | NG |
| Greenstar 18i System | 41-311-86 | NG |
| Greenstar 24i System | 41-311-68 | NG |
| Greenstar 12i System LPG | 41-311-69 | LPG |
| Greenstar 15i System LPG | 41-311-85 | LPG |
| Greenstar 18i System LPG | 41-311-87 | LPG |
| Greenstar 24i System LPG | 41-311-70 | LPG |
Source: Greenstar i System wall hung RSF gas fired condensing boiler installation, commissioning and servicing instructions, 6 720 644 743a (2010/10).
Sections: Cover (GC numbers); 2.2 Technical data (Table 6); 5.5 Commissioning; 5.5.1 Checking the gas inlet pressure (Figs. 61 to 63); 5.5.2 Checking the gas rate; 6.2 Check the gas inlet pressure; 6.3 Checking flue integrity; 6.4 Setting the boiler to maximum; 6.5 Flue gas analysis; 6.6 Setting the air/gas ratio; 6.6.1 Setting the CO/CO₂ (Table 24).
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.