Glow-worm Checked against MI

Glow-worm Ultracom sxi system (18sxi, 30sxi)

System boiler, natural gas (LPG by conversion)

Combustion figures

Figure	Natural gas (G20)	LPG (G31)
CO₂ at high rate More infoHide info Same table for maximum and minimum rate. Wait until the CO₂ is stable. Section 1 also gives NG burner CO₂ as 9.3 nominal case on, 9.1 nominal case off. LPG 18sxi setting: the section 13 table gives 10.1%, the 12.9 LPG conversion table gives 10.0%; both are shown.	Check (case on) 8.5 to 9.6% Setting (case off) 9.1% +0.2 −0.5	18sxi check (case on) 9.2 to 10.2%, setting (case off) 10.1% +0.0 −1.0 (12.9 table: 10.0% +0.0 −1.0) 30sxi check (case on) 10.0 to 11.0%, setting (case off) 10.5% +0.3 −0.8
CO₂ at low rate More infoHide info Same table for maximum and minimum rate. Adjustment at minimum is very coarse: no more than 1/8 of a turn at a time, then wait 1 minute. LPG 18sxi setting differs between the two tables (10.1% in section 13, 10.0% in 12.9).	Check (case on) 8.5 to 9.6% Setting (case off) 9.1% +0.2 −0.5	18sxi check (case on) 9.2 to 10.2%, setting (case off) 10.1% +0.0 −1.0 (12.9 table: 10.0% +0.0 −1.0) 30sxi check (case on) 10.0 to 11.0%, setting (case off) 10.5% +0.3 −0.8
Maximum CO	Not given in MI	Not given in MI
CO/CO₂ ratio More infoHide info Must not exceed this value. If it does, a full service is needed; if still too high after servicing, the boiler must be disconnected.	0.004	0.004
O₂	Not given in MI	Not given in MI
Working inlet pressure More infoHide info Nominal supply pressure, checked at the gas service isolation valve test point with all other gas appliances operating and the boiler forced to maximum. The MI says the maximum heat input can still be reached at an inlet pressure down to 15 mbar (MI 12.5; it doesn’t say which gas).	Appliance inlet 20 mbar	Appliance inlet 37 mbar
Gas rate at maximum More infoHide info Approximate, after 10 minutes from cold. 30sxi NG: section 1 gives 3.0 m³/h but the gas rate table in 12.5 gives 2.0 m³/h; both are shown.	18sxi 2.0 m³/h 30sxi 3.0 m³/h (12.5 gas rate table: 2.0 m³/h)	18sxi 1.47 kg/hr 30sxi 2.22 kg/hr

From 0020020821-04 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

Model	GC number	Gas
Ultracom 18sxi	41-019-07	NG
Ultracom 30sxi	41-019-08	NG

Source: Glow-worm Ultracom 18sxi, 30sxi Installation and Servicing, 0020020821-04 09.09.

Sections: 1 Boiler Specification; 12.3 Gas Supply; 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, Maximum rate check and adjustment, Minimum rate check and adjustment, Re-check CO2 and check the CO/CO2 combustion ratio.

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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.