Glow-worm sxi system (18sxi, 30sxi)
System boiler, natural gas (30sxi LPG conversion)
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoTable 2 and 11.5 don’t say which rate. 12.6 gives these figures at maximum fan speed (service potentiometer fully clockwise: display 57 ±1 for 30sxi, 41 ±1 for 18sxi). The manual contradicts itself on the case-on figures: NG case on is 9.3% +0.3 −0.5 in Table 2 and 11.5 but 9.1% +0.3 −0.5 in 12.6; LPG case on is 10.7% +0.3 −0.8 in 11.5 but 10.7% +0.3 −0.7 in 12.6. 12.6 also says the final maximum rate recheck should be “9.1+0.2-0.5 ± 0.2%”. LPG is the 30sxi only, after conversion. The LPG conversion procedure (section 11) says that after setting combustion, with the service potentiometer turned fully anti-clockwise (normal running), CO₂ should stay between 9.8% and 10.8%. |
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CO₂ at low rate More infoHide infoService potentiometer at the mid-point (3 o’clock): fan 1200 ±100 rpm, display flashes ‘12’. Measured with the front and inner casing panels off; MI gives no case-on figure at low rate. NG from 12.6; LPG (30sxi only) from the LPG conversion procedure in section 11, step 9. | 9.1% +0.2 −0.5 | 10.5% ± 0.2% |
Maximum CO | Not given in MI | Not given in MI |
CO/CO₂ ratio | Not given in MI | Not given in MI |
O₂ | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoNG: 1.3 says 20 mbar at the boiler; 11.5 says 20 mb at the gas valve pressure test point with the boiler at full rate. No tolerance given. LPG: section 11 and 11.5 say the supply pressure should be 37 mb. Measurement point not stated in MI. |
| 37 mbar |
Gas rate at maximum More infoHide infoApproximate, after 10 minutes from cold (Table 2). At minimum: 0.53 m³/h for both sizes. Check with the gas meter test dial at least 10 minutes after the burner has lit, with all other gas appliances off (11.5). |
| Not given in MI |
From 0020008155A.02.05
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 |
|---|---|---|
| 18sxi | 41-047-72 | NG |
| 30sxi | 41-047-62 | NG |
| 30sxi converted to LPG | 41-047-62 | LPG |
Source: Glow-worm 18sxi, 30sxi High Efficiency Condensing System Boiler Instructions for Use, Installation and Servicing, 0020008155A.02.05.
Sections: 1.1 Important notice; 1.3 Gas supply; 1.4 Technical data (Diagram 1.2, Table 2); 11 Commissioning: LPG conversion (30sxi only); 11.5 Testing - Gas; 12.6 Combustion check.
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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.