Rumford fireplaces hold lots of paradoxes, not the least of which is the generally accepted superiority of its advanced design relative to modern ones. The unusual and highly efficient dimensions and curves of these revolutionary fireplaces were conceived by an American loyal to Britain in 1796. This and other ‘oddities’ make these fireplaces as intriguing as the ‘Bavarian Circle of the Holy Roman Empire’.
That is the circle within which a then-British physicist who was born and grew up in Woburn, Massachusetts, as Benjamin Thompson became the paradoxical Count Rumford. ‘The nature of heat’ is what attracted his interest as a pure scientist. His fireplace design curved what was straight and straightened what was sloped.
The Paradoxical Rumford Effect
To comply with safety standards, today’s fireplaces have deep fireboxes with vertically short walls, creating something like a harbor entrance or partial dam for smoke. They have straight edged throats that require fireplace smoke to turn their corners before leaving the house. Traditional fireplaces — which is to say modern fireplaces — have back walls that slope towards the front. Their design presents very little surface area for heat to ascend up the fireback before it rolls out of the house.
The fireplace Rumford designed more than 200 years ago is as ‘peculiar’ now as it was then. Relative to our fireplaces, the opening presents a much wider angle because the firebox is much shallower; the side framing does not have to be as steep. The back wall is tall and straight, which creates radiant heat for longer as fireplace heat climbs a bigger fireback surface. The throat is sloped so smoke can pass smoothly through it; it doesn’t race in and choke up the way it does in ‘modern’ fireplaces.
Paradoxically, the fireplace that looks like it should leave more smoke in the room actually takes more out of it. The ‘tiny’ flue and ‘huge’ opening combine through the laws of physics to achieve the opposite of what modern thinking concludes. As interesting as the ‘odd’ man who designed it, the Rumford fireplace has the potential to again be revolutionary.
If you have any questions regarding your Rumford fireplace, please don’t hesitate to call. We’ll come out, and perform an expert inspection of your entire chimney system.