Isar with a 5 meter flue run

[Toxic Ted]

Chaps, i have an Isar to look at with a twin pipe 5m flue run which needs axing. Really badly designed apartments and going to be a nightmare to get a new flue in as the ceilings were put up after the boiler and flue went in. Walking away isn't an option and i'm thinking i'll have to wreck the ceiling to get a concentric in. Who's had a crap sandwich like this one and what did you throw in?

 

[newcastle phill]

....The towel

 

[gassed up]

Keston combi with the 50mm solvent weld flue. Basically an ideal logic/independent. Flue install gives more flexibility, but the boilers are a bit pricey.