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Glow-worm Checked against MI

Glow-worm Ultracom 2 cxi combi (24cxi, 30cxi, 35cxi)

Combi, natural gas, convertible to LPG

Combustion figures

FigureNatural gas (G20)LPG (G31)
CO₂ at high rate
More infoHide infoSame for all sizes. Check at maximum in test mode P.01 set to 100, waiting about 5 minutes for a stable reading (MI 18.3.3). The technical data (MI 5) gives the same figures as CO₂ at Qmax DHW. The manual contradicts itself: the gas conversion table (MI 16.1.2) gives case on and case off the other way round, G20 case ON 9 ± 0.2% and case OFF 9.2 ± 0.3%, G31 case ON 10.1 ± 0.2% and case OFF 10.3 ± 0.3%.
Case on (check)
9.2 ± 0.3%
Case off (setting)
9 ± 0.2%
Case on (check)
10.3 ± 0.3%
Case off (setting)
10.1 ± 0.2%
CO₂ at low rate
More infoHide infoSame for all sizes. Given only in the technical data (MI 5), as CO₂ at Qmin.
Case on
8.9 ± 0.3%
Case off
8.7 ± 0.2%
Case on
9.8 ± 0.3%
Case off
9.6 ± 0.2%
Maximum CO
Not given in MINot given in MI
CO/CO₂ ratio
More infoHide infoFrom the maximum rate check table (MI 18.3.3). The MI says the CO/CO₂ ratio must not exceed this value.
0.0040.004
O₂
Not given in MINot given in MI
Working inlet pressure
More infoHide infoNominal supply pressure, checked at the gas service isolation valve test point with all other gas appliances working (MI 12.6.1). No range is given. The technical data also lists inlet pressure as 20 mbar (NG) and 37 mbar (LPG). The MI adds that the safe nominal maximum heat input can be reached at an inlet pressure down to 15 mbar (gas type not stated).
Appliance inlet
20 mbar
Appliance inlet
37 mbar
Gas rate at maximum
More infoHide infoApproximate, at the gas meter, 10 minutes after lighting from cold, boiler forced to maximum with test mode P.01 at 100 (MI 12.6.2). The technical data gives the same figures as Maximum DHW gas flow rate; Maximum heating gas flow rate is lower (NG 1.96, 2.65, 3.24 m³/h; LPG 1.44, 1.94, 2.37 kg/h).
24cxi
2.70 m³/h
30cxi
3.24 m³/h
35cxi
3.77 m³/h
24cxi
1.98 kg/h
30cxi
2.38 kg/h
35cxi
2.77 kg/h

From 0020085231_02 - 05/10

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
24cxi47-019-10NG
30cxi47-019-11NG
35cxi47-019-12NG

Source: Glow-worm Ultracom2 cxi Installation and Servicing, 0020085231_02 - 05/10.

Sections: 5 Technical data; 12.6 Gas rates (12.6.1 Operational gas inlet pressure, 12.6.2 Gas rate); 13.3 CO2 measurement; 16.1.2 Adjusting the maximum power setting; 18.3 Combustion check and setting the air/gas ratio valve (18.3.3 Maximum rate check and adjustment).

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.