Vaillant ecoTEC exclusive system (627 VU 256/5-7 H-GB)
System boiler, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoThe manual says to measure the CO/CO₂ content at maximum and minimum load after calibration (sections 7.13.4 and 7.13.5) but gives no CO₂ figure. It also says that, as the product monitors the combustion continuously, you do not need to check the combustion. | Not given in MI | Not given in MI |
CO₂ at low rate | Not given in MI | Not given in MI |
Maximum CO More infoHide infoBenchmark flowchart (Appendix G), at maximum and minimum rate. The same flowchart’s re-check box (after checking the burner, internal flue, door and case seals) says less than 335 ppm instead. The manual doesn’t explain the difference. | Less than 350 ppm | Less than 350 ppm |
CO/CO₂ ratio More infoHide infoBenchmark flowchart (Appendix G), at maximum and minimum rate. | Less than 0.004 | Less than 0.004 |
O₂ | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoSection 7.13.3: at the measuring nipple on the gas valve, boiler at full load in check programme P.01, measured against atmospheric pressure. Nominal gas connection pressure (technical data): NG 20.0 mbar, LPG (G31 propane) 37.0 mbar. Diagnostics code D.087 also has a Propane 50 mbar setting; the manual gives no working pressure range for it. |
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Gas rate at maximum More infoHide infoTechnical data: at 15 °C and 1013 mbar, based on hot water generation. Section 7.13.2: measure at the gas meter, front casing fitted, after at least 5 minutes in check programme P.01. That section also has a natural gas rate table listed by Qnw from the data plate (nominal, +5%, −10%), but the manual doesn’t say which row is the 627. | 3.2 m³/h | 2.35 kg/h |
Flue integrity More infoHide infoBenchmark flowchart (Appendix G): at the air inlet test point, boiler at maximum rate. Section 9.1 (troubleshooting) gives different figures as signs of recirculation at the air test point: O₂ in the intake air < 20 vol.% or intake air CO ≥ 100 ppm. The manual doesn’t explain the difference. | O₂ ≥ 20.6% CO₂ < 0.2% | O₂ ≥ 20.6% CO₂ < 0.2% |
From 0020193966_02 (20.10.2017)
Enter service mode for high and low rate
High rate
Low rate
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| ecoTEC exclusive 627 (VU 256/5-7 (H-GB)) | 41-694-02 | Not stated |
Source: ecoTEC exclusive 627 (VU 256/5-7 (H-GB)) installation and maintenance instructions, 0020193966_02 (20.10.2017).
Sections: 2.3 Validity of the instructions; 3.2 Information on the identification plate; 5.1.1 Information on liquefied petroleum gas operation; 7.3.9 Gas type; 7.6 Using check programmes; 7.13.1 Checking the leak-tightness of the flue gas installation and flue gas recirculation; 7.13.2 Checking the gas flow rate; 7.13.3 Checking the gas flow pressure; 7.13.4 Calibrating the heat generator and measuring the CO/CO₂ content and gas flow in heating mode; 7.13.5 Calibrating the heat generator and measuring the CO/CO₂ content and gas flow in cylinder charging mode; 9.1 Comfort protection mode for the heat cell; Appendix B Overview of diagnostics codes (D.087); Appendix G Commissioning checklist (Benchmark CO and combustion ratio check); Appendix J Technical data.
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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.