Vaillant Checked against MI

Vaillant ecoTEC plus VU system (612, 615, 618, 624, 630, 637)

System boiler, natural gas and LPG

Combustion figures

Figure	Natural gas (G20)	LPG (G31)
CO₂ at high rate More infoHide info Table 12.1 (Factory gas setting): after 5 minutes at full load (test program P.01), at the flue gas analysis point. The MI’s check (12.1.3) has the front casing removed, and when adjusting you set the case-off figure (MI 12.1.4). The MI says combustion is factory set and no combustion measurement is needed to set up the boiler (MI 10.11.1); check or adjust CO₂ after replacing the gas valve, after a gas conversion, or if incorrect combustion is suspected (MI 12.1.3).	Case on 7.8–10.2% Case off 7.6–10.0%	Case on 9.7–10.7% Case off 9.5–10.5%
CO₂ at low rate	Not given in MI	Not given in MI
Maximum CO More infoHide info The MI disagrees with itself. Its own table 12.1 gives < 250 ppm at full load. The Benchmark flowchart at the back of the MI (PDF p. 85) gives < 350 ppm at maximum and minimum rate, and < 335 ppm in its re-check box after the seals have been checked. The MI doesn’t say which to use.	Full load (table 12.1) < 250 ppm Max and min rate (Benchmark flowchart) < 350 ppm	Full load (table 12.1) < 250 ppm Max and min rate (Benchmark flowchart) < 350 ppm
CO/CO₂ ratio More infoHide info The MI disagrees with itself. Table 12.1 gives the ratio without stating the rate. The Benchmark flowchart at the back of the MI (PDF p. 85) gives < 0.004 at maximum and minimum rate. The MI doesn’t say which to use.	Table 12.1 < 0.0031 Max and min rate (Benchmark flowchart) < 0.004	Table 12.1 < 0.0026 Max and min rate (Benchmark flowchart) < 0.004
O₂	Not given in MI	Not given in MI
Working inlet pressure More infoHide info Table 10.3: minimum and maximum at the reference test point (the lower measuring nipple on the gas valve), boiler at full load (test program P.01), front casing off. The MI gives NG 1.3–2.3 kPa (13–23 mbar) and LPG 2.3–4.3 kPa (23–43 mbar). Technical data (table 17.1) gives the gas connection pressure as 20 mbar NG and 37 mbar LPG, without saying where it’s measured.	Gas valve test point 13–23 mbar	Gas valve test point 23–43 mbar
Gas rate at maximum More infoHide info Table 10.2 (as per BS EN 483): nominal rate, with the MI’s −10% and +5% limits in brackets. Measure at the gas meter with the front casing on, at least 5 minutes into test program P.01, with all other gas appliances off. Table 10.2 lists rates by nominal output (12–37 kW) rather than by model. Technical data (table 17.1) gives the same rates rounded. The 612 and 615 are approved for natural gas only (table 1.2), but table 10.2 still prints propane rates for 12 and 15 kW.	612 1.31 m³/h (1.18–1.38) 615 1.64 m³/h (1.48–1.72) 618 1.97 m³/h (1.77–2.07) 624 2.61 m³/h (2.35–2.74) 630 3.27 m³/h (2.94–3.43) 637 4.03 m³/h (3.63–4.23)	612 0.96 kg/h (0.86–1.01) 615 1.20 kg/h (1.08–1.26) 618 1.44 kg/h (1.30–1.51) 624 1.92 kg/h (1.73–2.02) 630 2.40 kg/h (2.16–2.52) 637 2.96 kg/h (2.66–3.11)
Flue integrity More infoHide info From the Benchmark flowchart (PDF p. 85): at the air inlet test point, boiler at maximum rate. MI 10.11.2 says to check at the air measure point with the analyser and, if you find any CO or CO₂ in the fresh air, look for a flue gas leak or recirculation; it strongly recommends this check where the flue is longer than 2 m.	O₂ ≥ 20.6% CO₂ < 0.2%	O₂ ≥ 20.6% CO₂ < 0.2%

From 0020116700_06 GBIE 012014

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

Model	GC number	Gas
ecoTEC plus 612 (VU GB 126/5-5)	41-044-60	NG
ecoTEC plus 615 (VU GB 156/5-5)	41-044-61	NG
ecoTEC plus 618 (VU GB 186/5-5)	41-044-62	NG
ecoTEC plus 618 (VU GB 186/5-5) LPG	41-044-66	LPG
ecoTEC plus 624 (VU GB 246/5-5)	41-044-63	NG
ecoTEC plus 630 (VU GB 306/5-5)	41-044-64	NG
ecoTEC plus 630 (VU GB 306/5-5) LPG	41-044-67	LPG
ecoTEC plus 637 (VU GB 376/5-5)	41-044-65	NG

Source: Vaillant ecoTEC plus VU, VUW installation and maintenance instructions, 0020116700_06 GBIE 012014.

Sections: 1.3 Applicability of the instructions; 1.7 Type overview; 3 Description of the appliance; 10.4 Using test programs; 10.11 Checking the gas setting; 10.11.2 Checking for tightness of the flue gas installation and flue gas recirculation; 10.11.3 Checking the gas flow rate; 10.11.4 Checking the gas inlet working pressure; 12.1.3 Checking the CO/CO₂ ratio and the CO₂ concentration; 12.1.4 Adjusting the CO₂ concentration (or the air ratio); 17 Technical data; Benchmark CO and combustion ratio flowchart (PDF p. 85).

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.