Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 38·3.3
Size of flues
Flues should be sized to suit the intended appliance to ensure adequate discharge velocity and prevent flow reversal problems without imposing excessive flow resistance.
A flue should be sized to suit the intended appliance to ensure an adequate discharge velocity of the flue gas that will prevent flow reversal problems but will not impose excessive flow resistance.
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