About 1980, in an effort to understand the function and efficiency of fireplaces better, I read several articles and books on the subject and soon realized that the open fireplaces that I had been servicing in my chimney sweeping business for the previous three years were modern fireplaces that somehow had gotten away from good design features. Based on writings of such experts as Count Rumford, it appears that over the past 80 or 100 years masons have seemed to unknowingly removed efficiency and function from fireplace construction in exchange for speed and simplicity of construction. The fireplaces I would see on a daily basis were deep rectangle boxes with squared off lintels and corbelled breasts leading back to throat dampers and a deep smoke shelf. Owners of these fireplaces often complained of smoking, odor, and drafting problems. Even bigger complaints were that their fireplace did not put any heat back into the room.
Frustrated, I wondered why efficient fireplace design had disappeared. My conclusion was, that with the arrival of oil, gas, electricity and central heating, the need for efficient fireplaces was no longer as important. Ease of building became more important. In fact, for a period of time many houses were built without fireplaces altogether. Soon fireplaces were being added back into houses, but more for the ambiance and romantic aspects they added. In recent years the efficiency of fireplaces has become important to consumers again as the awareness of the environment and cost of fuel has increased.
In an effort to build better fireplaces, I began to add Rumford fireplace design features to the fireplaces I was building for my clients. Sharper angled sidewalls, vertically straight back walls, no throat damper or smoke shelf, smooth curved throats, the absence of wide lintel supports, taller openings and the smooth transition all the way from the fireplace to the. Setting the sidewall angles and sizing the firebox was fairly easy. Building the throat lintel and smoke chamber proved to be much more difficult.
I realized that a poured throat and lintel would accomplish many things, smooth finish to the throat, strong lintel without squaring off with angle iron, speed in building. The first few I built were rather primitive and took a lot of time to construct, but the resulting throat worked perfectly. I built fireplaces with as low as 1:15 flue/fireplace ratios and they would draw beautifully. In fact one customer would later joke with me that they don’t let their kids walk too close to the fireplace opening when it’s burning as the great draft may suck them up the flue. The problem was I was spending days building forms to pour the throat on each fireplace.
Many masons I have spoken with are unfamiliar with Rumford fireplace design, and of those that are, most have never built the Rumford design and don’t know how to. In recent years, the very knowledgeable Jim Buckley and Superior Clay Corp. have developed excellent Rumford fireplace components that make proper construction by masons with no prior Rumford experience possible. But the cost of components and the performance history of clay tile (flue tiles cracking) in chimneys left me looking for a better way.
My desire was to develop a set of reusable steel forms and an instruction manual that would allow both masons and chimney service companies to successfully and correctly build uniform, efficient, cleaner burning Rumford fireplaces every time, quickly and easily at a low cost.
I have accomplished that goal and now manufacture the Hart-Rumford reusable forms that set up in minutes and can be reused hundreds of times. Cost of materials to pour the throat and lintel is about $125.00 saving you hundreds of dollars compared to prefabricated throat components. By following the step by step instructions and using the forms, you can’t go wrong and because you can reuse them over and over again, the cost of every fireplace you build goes way down.
You will also be thrilled with the beautiful throat/lintel when you pull the forms off and your customer will be thrilled with the great performance of their new Rumford Fireplace.