Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 76·5.23
Installation requirements for flexible metal flue liners
Flexible metal flue liners must be installed as one complete length without joints, with space between chimney and liner left empty unless the manufacturer instructs otherwise. Double-skin liners and BS 715 liners must follow manufacturer or BS standards instructions.
A flexible metal flue liner should be installed in one complete length without joints within the chimney. Other than for sealing at the top and the bottom, the space between the chimney and the liner should be left empty unless this is contrary to the manufacturer's instructions. Double skin flexible flue liners should be installed in accordance with manufacturer's installation instructions. BS 715 liners should be installed in accordance with BS 5440: Part 1.
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