jlacd, heat rises so any heat generated by any fire will rise. A flue is only a posh name for a tube to exhaust the hot gases.
There are safety regulations in place for distance and height of exhaust stack or chimney from your property (call it what you will).
Take a look at www.trustcorgi.com/ for these safety gas rules and installations.
Thanks Rich... I'm not interested in gas again, but if I could put another wood-burner into the existing space, with minimal disruption I'd be a happy bunny!
No, I meant that the waste gas from the log burner which is potentially dangerous so the positioning of the flue is very important and the details are shown on the trustcorgi website.
I quite agree with you over wanting a simple installation process though I think it's actually simpler to install a log burner on an external wall than using an existing chimney.
By the looks of things a dual-fuel burner may be the best option for me.