Glow-worm MicraCom combi (24c-AS/1, 28c-AS/1)
Combi, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoAt full load, from the setting table in MI 12.2. The commissioning check in MI 9.6.5 (case on, check programme P.01, after at least five minutes, sensor in the centre of the flue pipe) gives a wider tolerance: NG 9.2 ±1 %, LPG 10.6 ±0.5 %. The MI gives both; it doesn’t explain the difference. |
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CO₂ at low rate | Not given in MI | Not given in MI |
Maximum CO More infoHide infoAt full load, case on or off (MI 12.2). The Benchmark commissioning flow chart in the MI (Appendix H) uses the general limits of less than 350 ppm CO and a CO/CO₂ ratio less than 0.004 at maximum and minimum rate (one box says 335 ppm). | ≤ 250 ppm | ≤ 250 ppm |
CO/CO₂ ratio More infoHide infoAt full load, case on or off (MI 12.2). The Benchmark flow chart (Appendix H) gives the general limit of less than 0.004. | ≤ 0.0027 | ≤ 0.0024 |
O₂ at high rate More infoHide infoAt full load (MI 12.2). |
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O₂ at low rate | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoMeasured at the test nipple on the gas valve, with check programme P.01 at maximum output. The MI says that because it is measured at the gas valve, the minimum may be 1 mbar lower than shown. Technical data gives a gas connection pressure of 20.0 mbar (NG) and 37.0 mbar (LPG), without saying where. |
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Gas rate at maximum More infoHide infoNominal figures from the gas flow rate table (MI 9.6.3), at 18.8 / 24 kW (24c) and 24.5 / 28 kW (28c) heat input. Measured at the gas meter, case on, check programme P.01, after at least five minutes, other gas appliances off. The table also gives +5% and −10% limits for each figure. Technical data (MI 3) gives slightly different figures: NG heating 1.99 m³/h (24c) and 2.59 m³/h (28c), NG hot water 2.54 m³/h (24c) and 2.96 m³/h (28c); LPG in kg/h only, heating 1.47 and 1.91 kg/h, hot water 1.86 and 2.18 kg/h. |
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Flue integrity More infoHide infoFrom the Benchmark commissioning flow chart (Appendix H), at the air inlet test point, boiler at maximum. MI 9.6.2 says to use the air analysis point on extended flues and gives no figures of its own. | O₂ ≥ 20.6% CO₂ < 0.2% | O₂ ≥ 20.6% CO₂ < 0.2% |
From 0020289288_03 – 14.10.2020
Enter service mode for high and low rate
High rate
Low rate
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| MicraCom 24c-AS/1 (H-GB) | 47-019-58 | NG |
| MicraCom 28c-AS/1 (H-GB) | 47-019-59 | NG |
Source: Glow-worm MicraCom 24c-AS/1, 28c-AS/1 installation and maintenance instructions, 0020289288_03 – 14.10.2020.
Sections: 3 Technical data; 4 Notes on the documentation (product article number); 9.6.2 Checking the air/flue pipe/flue gas recirculation; 9.6.3 Checking the gas flow rate; 9.6.4 Checking the gas connection pressure/gas flow pressure; 9.6.5 Checking the CO₂ content; 9.6.6 Performing a gas conversion; 12.2 Checking and setting the CO₂ content; E Check programmes; H Commissioning Flow Chart.
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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.