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Alpha Alpha CD90S and 115S system (CD90S, CD115S)

System boiler (commercial, over 70 kW), natural gas and LPG

Combustion figures

Figure	Natural gas (G20)	LPG (G31)
CO₂ CO₂ at high rate More infoHide info MI section 2.8 Performance data, CH Max column. The table gives the tolerance as ± 0.2% for all figures.	CD90S 9.30% ± 0.2 CD115S 9.45% ± 0.2	10.7% ± 0.2
CO₂ CO₂ at low rate More infoHide info MI section 2.8 Performance data, Min column.	CD90S 9.10% ± 0.2 CD115S 8.95% ± 0.2	CD90S 10.2% ± 0.2 CD115S 10.3% ± 0.2
CO Maximum CO	Not given in MI	Not given in MI
Ratio CO/CO₂ ratio More infoHide info From the routine servicing notes (section 6): if the ratio measured before servicing is greater than 0.003 the heat exchanger needs cleaning, and after reassembly the ratio must be less than 0.003. Measured at the flue sampling point.	Less than 0.003	Less than 0.003
O₂ O₂	Not given in MI	Not given in MI
mbar Working inlet pressure More infoHide info Measurement point not stated in MI. Section 3.1 says to ensure the inlet supply pressure is at least 20 mbar for natural gas or 37 mbar for propane. The gas valve has an inlet gas pressure test point (Fig. 21).	At least 20 mbar	At least 37 mbar
Rate Gas rate at maximum More infoHide info Section 2.1. Section 3.1 also gives the LPG gas rate as 7.17 kg/h (14 litres/h of liquid gas) for the CD90S and 8.76 kg/h (17.2 litres/h) for the CD115S.	CD90S 8.9 m³/h CD115S 10.6 m³/h	CD90S 3.5 m³/h CD115S 4.2 m³/h

From 03/10/D243 (© Alpha Therm Limited 2010)

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

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.