Hi Yes you can alter the flue. i had the same problem. i put a conservatory on the back of my house and either had to move the boiler which was going to cost £700 or alter the flue. I got onto potterton who sent me a brochure with all of the flue options for that boiler. i then ordered the flue kit through jewsons which cost £150
Fitted it myself
Result
John, May 2007
you cant extent the flue no. you wont be able to get the flue parts now as the boiler is obsolete. boiler will have to be moved somewhere else... loft or air cupboard maybe?