[Closed] wood burner: 150mm flue outlet but my chimney is unlikely to support 6 inches!

Please ensure that no euphemisms are hurt during the production of this thread...

I have chosen a stove. mistakenly thinking it was a 125mm outlet. Not bought yet but I WANT THAT ONE.

Now a previous fitter suggested not to bother lining the chimney - nothing to do with flue size particularly, he just thought that it was unnecessary. I've had a couple more out to do surveys and they seem to think that the liner would be a much better option. Reading around, I tend to agree.

What are my options? The chimney is 7" square at the base but there are constrictions further up that would require a flexible flue liner to get around. 5" liner seems feasible but not 6". Is there any advantage to putting a 6" liner up "as far as possible" and leaving the remainder unlined, are there any ultra flexible liners that might be suitable?

I know that I can't use a 5" liner with an adaptor for legal reasons. What is the worst that could happen if I leave it unlined? Pics below.[url= http://farm8.staticflickr.com/7370/10290947306_cfa893a54f.jp g" target="_blank">http://farm8.staticflickr.com/7370/10290947306_cfa893a54f.jp g"/> [/img][/url]
[url= http://www.flickr.com/photos/58244036@N02/10290947306/ ]P1020462[/url] by [url= http://www.flickr.com/people/58244036@N02/ ]craigbart[/url], on Flickr
[url= http://farm8.staticflickr.com/7335/10290843564_9f6715a370.jp g" target="_blank">http://farm8.staticflickr.com/7335/10290843564_9f6715a370.jp g"/> [/img][/url]
[url= http://www.flickr.com/photos/58244036@N02/10290843564/ ]P1020459[/url] by [url= http://www.flickr.com/people/58244036@N02/ ]craigbart[/url], on Flickr