As far back as 1624... Louis Savot invented the first heat-circulating fireplace. His unit was installed in the Louvre, Paris, and became the prototype for Ben Franklin's 1742 Pennsylvania stove. The 1624 French fireplace achieved 30 to 45 percent more efficiency than do most American tract home fireplaces of today! Savot surrounded the grate of his creation with a metal chamber, which had warm air outlets above the fire opening. He also supplied the fire with air from under the floor. Thus, room drafts were reduced and combustion efficiency was further improved. Few people are aware that practically all of the technical features of Franklin's Pennsylvania stove were copied from earlier inventors.

The Owner Built Home: A How-to-do-it Book (1972)