by John Carter

Created on: October 22, 2008

How to build a Rumford Chimney

No one has designed a better chimney or a more energy efficient chimney in over 200 years then the Rumford Chimney. This was named after Lord Rumford the inventor. He was a physicist and inventor born in Woburn, Massachusetts in 1753 as Benjamin Thompson. He was also a Tory who evacuated from Boston with the British in 1776 and moved to England. This was after he was accused of informing on the Minutemen.

When he moved to London he experimented with gunpowder, signaling at sea, and published a paper on how to build a fireplace that heated but didn't smoke. King George III was so impressed with him that he knighted him. He assumed the name "Rumford" from his wife's birthplace now Concord, New Hampshire. To this day the Rumford Chimney is one of the best and most efficient you can build.

Later Sir Benjamin moved to Bavaria where he spent the next 11 years serving in various posts including minister of war. For his services to the Holy Roman Empire he was made a count, hence "Count Rumford."

The Rumford Fireplace was first introduced in the late 1790s as a means of improving the heating capabilities of the fireplace. Prior to its invention the traditional fireplace was deep. What he did was to move the firewall further forward in the fireplace making his fireplace quite shallow. This was done so the fireplace would reflect more heat into the room. He also angled the sidewalls to that even more heat was radiated into the room.

Above the fireplace was a smokebox 2 feet x 3 inches high x 4 inches deep with slanted sides leading to the chimney throat. The smokebox was the width of the fireplace, and was built so that it was directly above the fire. The last thing he did was to round the throat of the fireplace so the smoke moved more freely up the chimney.

This was named the "Rumford Fireplace" resulting in more heat to be felt by the occupants of the room. This was because the fireplace was only about 15 inches deep. The Rumford Chimney was also quite massive so that it would absorb and retain heat. By lighting all the fireplaces and the Dutch oven it would make the interior of the house so warm it would be uncomfortable to stay in the house on even the coldest of winter days.

The Masonry Institute of America has recently redesigned the Rumford Fireplace calling it the "BIA Fireplace." In essence it makes use of less bricks then the traditional Rumford Fireplace and removes the rounded throat from the fireplace. The construction of this chimney is explained in, "The Third Edition of the Fireplace and Chimney Handbook," as published by the Masonry Institute of America.

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