"Stu" wrote:

I'm about to install a woodburning stove. It will need an external twin
wall stainless steel flue on an outside wall. I have a few questions
and would be grateful if any experts can answer them.

No expert but I've been researching coz I'm planning to fit a
second (woodburning) boiler working in tandem with my gas-fired
one.

My stove has an 8" outlet. Can I use 12" flue outside rather than 8" ?
( I can get some 12" cheap !)

Will this increase or effect the 'draw' in any way ?

I plan on slightly less than 1 metre of stove pipe above the stove
going into the 12" Flue pipe. Does this sound reasonable ?

From what I've read 9ins is considered the limit for domestic
flues. The reason is that above 9ins the wider part of the flue
won't get warm enough to "draw" the smoke effectively, probably
resulting in some smokiness within the room.

riccip