Rumford Fireplace - Principle of Action

Principle of Action

The Rumford fireplace created a sensation in London when he introduced the idea of restricting the chimney opening to increase the updraught. He and his workers changed fireplaces by inserting bricks into the hearth to make the side walls angled and added a choke to the chimney to increase the speed of air going up the flue. It effectively produced a streamlined air flow, reducing turbulence so the smoke would go up into the chimney rather than lingering and often choking the residents. Many fashionable London houses were modified to his instructions, and became smoke-free as well as more efficient. Thompson became a celebrity when news of his success became widespread. In an age when fires were the principal source of heat, this simple alteration in the design of fireplaces was copied everywhere .

Rumford fireplaces were common from 1796, when Count Rumford first wrote about them, until about 1850. Jefferson had them built at Monticello, and Thoreau listed them among the modern conveniences that everyone took for granted. There are still many original Rumford fireplaces, often buried behind newer renovations. He also invented a cast iron stove which competed successfully with the famous Benjamin Franklin stove. Both devices gave much more control over the air flow into the fire, and were both much more efficient users of fuel. Such stoves were expensive, but saved so much fuel as to justify the cost of installation very quickly.