I have opened up to form a recess in an existing chimney breast for a range cooker (in a new kitchen installation) and this will have a flush fitting extractor hood set into a (new plasterboard and skimmed) soffit, with the existing brick flue above this soffit extending approx 6.5m to the top of the chimney pot.
The existing brickwork flue measures 235 x 235mm square. I thought of using the insulated (ie glass fibre wrapped aluminium hose 127mm dia which measures 177mm dia overall) but would assume the insulation will snag and get ripped off when pulling the liner down (or up?) the flue.
Therefore, depending on any feedback, I will fit a normal 125mm flexible 316 liner. I would be keen to know how to insulate such a flue to avoid risk of condensation from the warm steamy air being extracted through to the top of the flue. (The unheated loft is located directly above the above new kitchen).
Any reason why the flexible flue liner can't be pulled up from below with the person below feeding it in and man on roof pulling it up? I thought this might be easier as I intend to use a suspending cowl because the chimney pot needs to be preserved (tall Victorian louvred design) and feeding a 7m "snake" into such a chimney pot does not seem ideal.
Any helpful advice would be welcome.