On Fri, 07 Dec 2012 20:33:44 -0500, Perry Salazar
wrote:

My uncle was given a wood burning stove, Soffolk County in NY.He
checked
with a local installer and the price he quoted, my uncle felt it was
way too high. Anyway I'm looking for a mail order warehouse, and can
somebody tell me what I need.
Here is what he wants to do. The back of the stove has an 8" opening
and he wants to go thru the ceiling. That will be roughly 12 feet.Can
he reduce the pipe to 6" from the 8", will that work?

First off, you should not reduce the outlet size. If 8" is needed at
the bottom, it is needed at the top for proper draft.

Before you even start, get some professional advice either from an
installer or a proper book. Wrong installation can result in a burned
down house, even death from a fire.

I'm not up on the latest codes but triple wall tubing is generally
what is used in the US and there is a double wall Class A for Canada.

Find out what is needed to support the pipe, do a proper layout for
cleanouts, drip leg, flashing, and the proper height above the roof.
There are codes for that also.

Some towns require permits and inspections, as do some insurance
companies. There are also codes to stove placement to walls, etc.