TGD J 2014 – 3.9.5 – Rigid or flexible flue liners:

3.9.5 Rigid or flexible flue liners: Stainless steel rigid or flexible flue liners complying with the appropriate designation of IS EN 1856- 2:2009 and meeting the performance level specified in sub-section 3.7.1 and Table 6 may be used in an existing chimney. Flexible metal flue liners should be installed in one complete length without joints within the chimney. When being installed for a gas appliance in a flue lined chimney it should be sealed at the top and bottom, the space between the chimney and the liner should be left empty unless this is contrary to the manufacturer’s instructions. Flexible flue liners may not be appropriate for large non-lined chimneys without specialist advice.

C:BCARTGDtgd jTGD%20J%202014TGD%20J%202014%20-%20SECTION%203.9.5.pdf