On Apr 9, 8:15*am, Nyal Williams wrote:
What have you heard? *Anyone have any comments to offer?

I was going to guess that it referred to the dampers on steam engine
boilers but this reference
http://www.answers.com/topic/all-out states the term has been in use
since 1300. That obviously predates the steam engine, but perhaps not
other flue dampers.

Dampers can be rotary valves or sliding plates. Pulling a sliding
plate flue damper "all out" gives maximum flue draw and the hottest
fire.


Andy