I just installed a wood stove...

I wanted to use my existing chimney, but was told by several people and also
read several different places... That new wood stoves heat more efficiently
and therefore do not send as much heat up the chimney.

Therefore it is important to have the same size chimney as the wood stove to
get proper draft. Also I heard all sorts of nasty stuff about old existing
chimneys and that in every case, they should be lined.

The building inspector and insurance guy went strictly by my wood stove
manufacturers specs for chimney and installation requirements.

It was less expensive and better for me to install a new chimney in another
location than to have my existing chimney relined.

I don't know if all this applies to a wood furnace or not? The important
part is to get your insurance company to cover it, and do what is necessary
to get them to cover it. That was my main concern.