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Vaillant Checked against MI

Vaillant ecoTEC pro combi (30 H combi A, VUW 306/5-3)

Combi, natural gas (LPG figures given)

Combustion figures

FigureNatural gas (G20)LPG (G31)
CO₂ at high rate
More infoHide infoAfter 5 minutes in full load mode (check programme P.01), measured at the flue gas analysis point. If adjustment is needed, set CO₂ to the case-off value.
Case on
9.2% ± 1.0
Case off
9.0% ± 1.0
Case on
10.4% ± 0.5
Case off
10.2% ± 0.5
CO₂ at low rate
Not given in MINot given in MI
Maximum CO
More infoHide infoAt full load. The Benchmark commissioning flow chart in the appendix uses a different check: CO less than 350 ppm at maximum and minimum rate (one box says 335 ppm).
≤ 250 ppm≤ 250 ppm
CO/CO₂ ratio
More infoHide infoThe Benchmark commissioning flow chart in the appendix uses a ratio less than 0.004 at maximum and minimum rate.
≤ 0.0031≤ 0.0026
O₂ at high rate
More infoHide infoAfter 5 minutes in full load mode with the front casing closed.
4.5% ± 1.85.1% ± 0.8
O₂ at low rate
Not given in MINot given in MI
Working inlet pressure
More infoHide infoMeasured at the test nipple (lower screw) on the gas valve, at full load (check programme P.01). Technical data gives the gas flow pressure as NG 20.0 mbar, LPG 37.0 mbar.
Gas valve test point
13.0–23.0 mbar
Gas valve test point
23.0–43.0 mbar
Gas rate at maximum
More infoHide infoFrom the technical data (at 15 °C and 1013 mbar, based on hot water). The gas flow rate check table in section 9.11.3 lists outputs of 18.5 to 27.2 kW only, with no row matching this model’s 30.0 kW hot water output.
3.2 m³/h2.4 kg/h
Flue integrity
More infoHide infoAt the air inlet test point, boiler at maximum rate (Benchmark commissioning flow chart).
O₂ ≥ 20.6%
CO₂ < 0.2%
O₂ ≥ 20.6%
CO₂ < 0.2%

From 0020209589_04 (29.07.2020)

Enter service mode for high and low rate

High rate

Steps not added yet. Follow the MI.

Low rate

Steps not added yet. Follow the MI.
Ending the test: follow the MI.

Models and GC numbers

ModelGC numberGas
ecoTEC pro 30 H combi A VUW 306/5-347-044-52NG

Source: Vaillant ecoTEC pro VUW ..6/5-3 installation and maintenance instructions, 0020209589_04 (29.07.2020).

Sections: 3 Technical data; 4 Notes on the documentation (Gas Council number); 9.11.1 Checking the factory-set gas setting; 9.11.3 Checking the gas flow rate; 9.11.4 Checking the gas flow pressure; 9.11.5 Checking the CO₂ content and adjusting it (air index setting); 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.