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Alpha Alpha CD50S and 70S system (CD50S, CD70S)

System boiler, natural gas and LPG

Combustion figures

Figure	Natural gas (G20)	LPG (G31)
CO₂ CO₂ at high rate More infoHide info MI section 2.7 Performance data, CH Max column. The MI gives no conditions for the reading (case on or off, time after firing).	CD50S 9.30% ± 0.2% CD70S 9.25% ± 0.2%	CD50S 10.6% ± 0.2% CD70S 10.5% ± 0.2%
CO₂ CO₂ at low rate More infoHide info MI section 2.7 Performance data, Min column.	CD50S 9.25% ± 0.2% CD70S 9.00% ± 0.2%	CD50S 10.1% ± 0.2% CD70S 9.7% ± 0.2%
CO Maximum CO	Not given in MI	Not given in MI
Ratio CO/CO₂ ratio More infoHide info From the notes at the start of MI section 6 Routine servicing: if the ratio is greater than 0.003, clean the heat exchanger and recheck after reassembly. The MI does not split this by gas type.	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 MI section 3.1 Gas supply gives this as the minimum inlet supply pressure. Measurement point not stated in MI.	At least 20 mbar	At least 37 mbar
Rate Gas rate at maximum More infoHide info MI section 2.1 Performance. MI section 3.1 also gives LPG as CD50S 3.94 kg/h (7.6 litres/h of liquid gas) and CD70S 5.42 kg/h (10.4 litres/h of liquid gas).	CD50S 5.37 m³/h CD70S 7.4 m³/h	CD50S 2.15 m³/h CD70S 2.96 m³/h

From Part No. 1.027175 (06/08/D222)

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.