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Glow-worm Checked against MI

Glow-worm Ultracom cxi combi (24cxi, 30cxi, 38cxi)

Combi, natural gas (LPG by conversion)

Combustion figures

FigureNatural gas (G20)LPG (G31)
CO₂ at high rate
More infoHide infoCHECK column, case on. The MI uses one table for both maximum and minimum rate. If adjusting, set to the SETTING column, case off: NG 24cxi, 30cxi 9.1% +0.2/−0.5, 38cxi 8.8% +0.2/−0.5; LPG 24cxi 10.0% +0.0/−0.9, 30cxi 10.5% +0.3/−0.7, 38cxi 9.8% +0.2/−0.8. The Boiler Specification table (section 1) gives NG nominal CO₂ case on 9.3% (24cxi, 30cxi), 9.0% (38cxi), and case off 9.1% (24cxi, 30cxi), 8.8% (38cxi).
24cxi, 30cxi
8.5 to 9.6%
38cxi
8.5 to 9.3%
24cxi, 38cxi
9.2 to 10.2%
30cxi
10.0 to 11.0%
CO₂ at low rate
More infoHide infoCHECK column, case on. Same table as maximum rate: the MI gives no separate minimum rate figures. SETTING column (case off) as for high rate.
24cxi, 30cxi
8.5 to 9.6%
38cxi
8.5 to 9.3%
24cxi, 38cxi
9.2 to 10.2%
30cxi
10.0 to 11.0%
Maximum CO
Not given in MINot given in MI
CO/CO₂ ratio
More infoHide infoMust not exceed this value. If it does, a full service is needed (MI section 13).
0.0040.004
O₂
Not given in MINot given in MI
Working inlet pressure
More infoHide infoOperational supply pressure at the gas service isolation valve test point, with all other gas appliances working. The MI says the safe nominal maximum heat input can be achieved at an inlet pressure down to 15 mbar.
Appliance inlet
20 mbar (nominal)
Appliance inlet
37 mbar (nominal)
Gas rate at maximum
More infoHide infoApproximate, after 10 minutes from cold (commissioning table, MI section 12.5). The Boiler Specification table (section 1) gives a lower approximate CH maximum gas rate for NG: 24cxi 1.94 m³/h, 30cxi 2.45 m³/h, 38cxi 3.19 m³/h.
24cxi
2.24 m³/h
30cxi
2.80 m³/h
38cxi
4.06 m³/h
24cxi
1.88 kg/hr
30cxi
2.34 kg/hr
38cxi
2.98 kg/hr

From 0020020820-04 09.09

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
Ultracom 24cxi47-019-01NG
Ultracom 30cxi47-019-02NG
Ultracom 38cxi47-019-03NG

Source: Glow-worm Ultracom cxi Installation and Servicing, 0020020820-04 09.09.

Sections: 1 Boiler Specification; 12.4 Initial Lighting; 12.5 Check the Gas Inlet Pressure and Gas Rate; 12.9 LPG Conversion; 13 Servicing: Combustion check and setting the air/gas ratio valve (1. Maximum rate, 2. Minimum rate, 3. Re-check CO2 and CO/CO2 ratio).

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.