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Vaillant Checked against MI

Vaillant ecoTEC plus 937 combi (937)

Combi with 15 l stratified store, natural gas and LPG

Combustion figures

FigureNatural gas (G20)LPG (G31)
CO₂ at high rate
More infoHide infoAfter 5 minutes at full load (test program P.1), measured at the flue gas analysis point. When adjusting, set to the front casing removed figure (MI 8.1.4). LPG figures are for the boiler converted with Vaillant kit 0020010641.
Front casing closed
9.2% ± 1.0
Front casing removed
9.0% ± 1.0
Front casing closed
10.2% ± 0.5
Front casing removed
10.0% ± 0.5
CO₂ at low rate
Not given in MINot given in MI
Maximum CO
More infoHide infoAt full load.
< 250 ppm< 250 ppm
CO/CO₂ ratio
< 0.0031< 0.0026
O₂
Not given in MINot given in MI
Working inlet pressure
More infoHide infoMinimum and maximum at the reference test point marked in on the gas valve, boiler at full load in test program P.1. MI 5.11 says the supply pipework must give 20 mbar at the boiler inlet at maximum output (gas type not stated). Technical data gives required gas flow pressure: NG 20 mbar, LPG 37 mbar (point not stated).
Gas valve test point
15–23 mbar
Gas valve test point
23–43 mbar
Gas rate at maximum
More infoHide infoNominal net heat input 37.8 kW (BS EN 483). Measure at the gas meter with the front casing fitted, after at least 5 minutes in test program P.1, with all other gas appliances off.
4.00 m³/h (+5% 4.20, −10% 3.60)2.94 kg/h (+5% 3.09, −10% 2.65)
Flue integrity
More infoHide infoCheck with the flue gas analyser at the air measure point (MI Fig. 6.6). Strongly recommended if the flue is longer than 2 m. If any CO or CO₂ is found in the fresh air, find and correct the leak or recirculation; if it can’t be corrected, don’t start the boiler.
No CO or CO₂ at the air measure pointNo CO or CO₂ at the air measure point

From 0020031552_06 GBIE 102010

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 plus 93747-044-39NG

Source: Vaillant ecoTEC plus 937 installation and maintenance instructions, 0020031552_06 GBIE 102010.

Sections: 1.8 Gas Council Number; 2.2 Technical data; 2.5 Functional description; 5.11 Gas connection; 6.9 Checking the gas setting; 6.9.1 Checking for tightness of the flue gas installation and flue gas recirculation; 6.9.2 Checking the gas flow rate; 6.9.3 Checking the gas inlet working pressure; 6.12 Converting the gas type; 8.1.3 Checking the CO₂ concentration; 8.1.4 Adjusting the CO₂ concentration (or the air ratio); 9.2 Test programmes.

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.