On Apr 9, 9:31*am, Andy wrote:
*Pulling a sliding
plate flue damper "all out" gives maximum flue draw and the hottest
fire.

On further reflection the term could have come from pipe organs where
"stops" are pulled out to control airflow and hence sound volume.
Pipe organs predate 1300. ref http://en.wikipedia.org/wiki/Pipe_organ

There must be a reference to the origin somewhere on the internet but
I didn't find it yet.

Andy