On Mon, 12 Nov 2012 14:51:20 +0000, Big Les Wade
wrote:

Also the existing chimney (into which the flue pipe will be inserted) is
quite narrow. The builder thinks it will only take a 5in pipe.

Then it will not comply with part J unless burning smokeless fuel,
even the exempt devices under the clean air act only allow for coal
and not wood.

There appears to be no exception when burning wood pellets even though
smaller than 150mm and balanced flues are allowed in other countries.

AJH