On Nov 12, 2:51*pm, Big Les Wade wrote:
Dave Liquorice posted

On Sat, 10 Nov 2012 18:18:44 -0000, Lawrence wrote:

Can you not fit the largest flue and them put a spigot plate at the
bottom to match your stove?

You can as in physically but I don't think the BCO would like it as it is
probably against the installation instructions of the stove.

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.

A large flue will slow down the flow of gases, the longer they take the
cooler they get and more chance of tar/soot deposition in the flue.

It will also affect the draw. I can't decide if it won't draw enough,
large column of air that will be hard to get moving, or draw too much,
wind over chimeny pot sucking a 7" column of air due to the venturi
effect being rather more than a 5" flued stove would want. Or a
combination of both depending on conditions...

--
Les

That is unusually small. 8" is normal.