Author – Todd Woofenden
All fireplaces are not created equal. In fact, other than factory-built fireplaces, no two fireplaces are the same. Even if your fireplace seems identical to your neighbor’s (suppose, for instance, that you both bought the same model of factory built fireplace) they can behave very differently depending on how you use them.
Traditional masonry fireplaces fall into two general categories:
A normal brick fireplace, most of which have an opening about 36″ wide, about 28″ high, and are 16″ to 20″ deep. The inner walls of the fireplace angle inward, and the back sometimes slopes forward a bit, but is sometimes nearly vertical.
Count Rumford (Sir Benjamin Thompson), an 18th century philosopher and scientist, wrote a book on fireplace design that stands in stark contrast to the “standard” design. Designed to increase heat transfer to the room (and thus reduce heat loss up the flue), Rumford fireplaces incorporate a shallower firebox and a higher opening, with the sides and back quite slanted. These fireplaces often look as if they would certainly spill smoke into the room. But a properly constructed Rumford fireplace does, in fact, deliver what Count Rumford promises. If you are designing a new home, talk to an experienced mason about it.
The art of building Rumford fireplaces was almost lost; but modern masons are starting to look once more at his design, and Rumford fireplaces are finding their way more frequently into new homes.
Some newer types of fireplaces include
Fireplaces built in a factory, of steel, cast iron, firebrick, and other manufactured materials, and installed on site, generally with factory-built chimneys.
Masonry fireplaces with metal liners. Standard brick or stone fireplaces incorporating a cast-iron or steel lining inside the fireplace.
Sometimes the metal liner incorporates an air space between two layers of metal. Ducts connected to this air space (usually you will see a grate on either side of the fireplace opening near the floor) draw cool air in at the base and vent warm air out higher (usually through another pair of grates above the mantel).
A relatively new addition to the lineup, modular masonry fireplaces are built of pre-fabricated masonry sections, which are assembled on-site. Some systems are designed for retro-fitting to existing chimneys, as a replacement system for a damaged or non-functional fireplace.
~ Todd Woofenden