New flue inside old flue?

[Jackie]

We are having a woodburning stove installed having taken out the old stove. The flexible liner diameter, double skin, might be less than the existing rigid tube 200mm liner though I don't know what the outside diameter of a 155mm double skinned liner would be. The artisan says the existing liner is too large and the smaller one would be better with the stove we are buying, a Supra Orlando Ollaire which takes a 155mm liner, inside diameter I assume. I have managed to get the old stove out and the liner sections that were between it and the bottom of the chimney but those sections in the chimney appear to be trapped in concrete at the base. I cannot get far enough up from the fireplace to chip out this concrete and to remove the old liner would mean demolishing part of a bedroom wall upstairs to get at it which I am not keen on doing. My question is this, is there any reason why the new liner could not be pulled up inside the old one to the top of the chimney assuming that it would fit, or is there some regulation against this?...............................J

[UlsterRugby1999]

Morning Jackie - (now I'm no expert but I have installed 1/2 dozen plus stoves) from what you have written there would nothing to stop you doing as you describe. In fact there would even be benefits from it too. Possibly less potential for condensation would be one. You say double skinned flexi flu liner, do you mean insulated flu liner. If yes, is it really required especially if its going to go inside the original 200mm flexi (Inox I'm assuming) flu. The insulated is very expensive. Just a thought.

[Jackie]

Yes I thought that it would only add to the safety of the system. I don't really know what double skinned means but the artisan, in his devis, wrote  " Tubage de conduit avec flexible inox double peau, homologué bois et charbon, diamètre 155 mm. Fournitures et main d'oeuvre  68 Euros each 8 units 544 Euros"  I think this 155 mm must be the inside diameter as the stove info specifies this but I don't know the outside diameter. Someone in another place has suggested a 30 mm air gap between the skins which would mean it would not fit inside the existing 200 mm conduit. I think I must contact the bloke and see what he says as I really don't want to take down part of the bedroom wall though he was negative when I suggested putting it inside the existing conduit when he first came round.............................................J 

 

[Jackie]

OK all installed now and the liner he fitted inside the old 200mm one was double skinned but not insulated. All seems to work but I have put on a post about the risks of using résine d'accrochage in the concrete skim I am putting over the old surrounding block work and another, in Pets, about problems we had with our cat and fumes from the stove paint on the first lighting, cheers......................................J