Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 59·Table 4.2
Size of flues for gas-fired appliances
Table 4.2 specifies minimum flue sizes for different gas-fired appliance types, including radiant/convector fires, ILFE fires, and DFE fires, with different requirements for new and existing flues.
Table 4.2 Size of flues for gas-fired appliances
Intended installation | Minimum flue size
Radiant/convector gas fire (new flue) | Circular - 125 mm diameter; Rectangular - 16500 mm2 cross-sectional area with a minimum side dimension of 90 mm
Radiant/convector gas fire (existing flue) | Circular - 125 mm diameter; Rectangular - 12000 mm2 cross-sectional area with a minimum side dimension of 63 mm
ILFE fire or DFE fire within a fireplace opening up to 500 mm x 550 mm | Circular or rectangular - Minimum flue dimension of 175 mm (diameter and side)
DFE fire installed in a fireplace opening in excess of 500 mm x 550 mm | Calculate in accordance with Section 3, paragraph 3.7 to 3.8.
Note: Some ILFE and DFE appliances are suitable for use with a circular flue with a diameter not less than 125 mm or a rectangular flue with a cross-sectional area of not less than 16500 mm2 with a minimum side dimension of 90 mm.
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