Worcester Bosch R29 & R40 HE conventional (ZB 7-28 R29 HE, ZB 11-40 R40 HE)
Conventional (heat only) boiler, natural gas, or LPG with a conversion kit
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFrom Table 14 (MI 7.1), CO₂ reading at max. rated heat output, at the flue gas testing point (234) with the probe about 135 mm in. No tolerance given. Table 14 labels the gases Natural gas type G20 and LPG G31 (propane), with one row for both sizes. The technical data (MI 1.9, Table 2) gives the same figures for both sizes. MI 7 says the setting is factory sealed at maximum and adjusting the rated and min. heat input isn’t necessary. | 9.2 % | 10.8 % |
CO₂ at low rate More infoHide infoThe manual contradicts itself for the R40. Table 14 (MI 7.1), which the gas/air ratio steps use, gives one figure for both sizes: 8.8 % (NG) and 10.5 % (LPG) at min. rated heat output. The technical data (MI 1.9, Table 2) agrees for the R 29 HE but gives 9.2 % (NG) and 10.8 % (LPG) for the R 40 HE, the same as its maximum. The MI doesn’t say which is right. No tolerance given. |
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Maximum CO | Not given in MI | Not given in MI |
CO/CO₂ ratio | Not given in MI | Not given in MI |
O₂ | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoMI 7 says natural gas appliances must not be operated if the gas supply pressure is below 18 mbar or above 24 mbar, and LPG appliances must not be operated if the supply pressure is below or above 37 mbar (printed like that). MI 5.1 gives the same limits, wording the LPG one as not 37 mbar at the inlet to the appliance. Both say to check at the gas supply pressure test point (7), which Fig. 3 (MI 1.7) shows on the gas valve. The MI doesn’t say whether the boiler should be running. Nominal gas supply pressure (MI 1.9, Table 2): NG G20 20 mbar, LPG 37 mbar. NG G20 appliances are factory set to Wobbe-Index 15 kWh/m³ and 20 mbar supply pressure and sealed (MI 7). |
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Gas rate at maximum More infoHide infoMaximum gas flow rate after 10 minutes from lighting (MI 1.9, Table 2), for NG G20 at CVnet 34.02 MJ/m³ and LPG at CVnet 88 MJ/m³ (as printed). Table 2 heads the sizes R 29 HE and R 40 HE, and gives a max. rated heat input of 27.7 kW and 40 kW. Table 18 (MI 9.3) gives a NG gas volume flow rate of 48.5 l/min at display code 100 (27.7 kW heat input), and the MI has no separate table for the R 40 HE. |
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Flue integrity More infoHide infoAt the testing point for combustion air (234.1) with the probe about 80 mm in, boiler in chimney sweep mode (MI 7.2.1). The MI words it as O₂ must not be less than 20,6 % and CO₂ must not exceed 0,2 %, and says this checks the gas tightness of a type C13 or C33 flue system. | O₂ ≥ 20.6% CO₂ ≤ 0.2% | O₂ ≥ 20.6% CO₂ ≤ 0.2% |
From 6 720 611 445 GB (05.04)
Enter service mode for high and low rate
High rate
- Hold the service button (spanner) until the display shows – – and the button lights.
- Turn the temperature control (radiator symbol, left knob) until the display shows 2.0. After a moment it shows 0.
- Turn the function control (right knob) until the display shows 2. for maximum. The display and service button flash.
- Or: hold the chimney sweep button until – – shows. Runs at maximum, or at the set heating output if it’s been limited.
Low rate
- Turn the function control anti-clockwise until the display shows 1. for minimum.
- Turn it back to 2. for maximum.
Ending the test
- Turn the function control anti-clockwise to the stop (0.), hold the service button until [ ] shows, then set both knobs back.
- Chimney sweep: hold the chimney sweep button until – – shows. It also ends by itself after 15 minutes.
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| ZB 7-28 R29 HE | 41-311-60 | NG |
| ZB 11-40 R40 HE | 41-311-61 | NG |
Source: Worcester R29 & R40 HE conventional wall mounted condensing boiler for central heating installation and servicing instructions, 6 720 611 445 GB (05.04).
Sections: Cover (GC numbers); 1.7 Function; 1.9 Technical data; 5.1 Commissioning; 7 Converting the appliance to different gas types (checking the gas supply pressure, Table 13 conversion kits); 7.1 Setting the gas/air ratio; 7.2.1 Testing the O₂ or CO₂ level in the combustion air; 7.2.2 Testing CO and CO₂; 9.3 Heating/hot water output settings (N.G).
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.