Manufactured Fireplaces

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Manufactured fireplaces are prefabricated steel boxes.  Fires inside of dwellings have been around since early man built a fire on the floor for heat and cooking.  In these early dwellings, smoke would escape by whatever route it could, or be blown back into the space.  Chimneys were invented much later, and aided a great deal in correcting the ventilation problem.

The fireplace has had a great number of designs and modifications throughout the centuries.  Prince Rupert in 1678 raised the grate for better air flow and venting.  The 1700’s saw important developments by Benjamin Franklin and Count Rumford.  Franklin developed a convection chamber that increased efficiency and improved air flow and venting.  Rumford designed a tall shallow firebox that was better at drawing smoke up and out of the building.  This design also improved radiant heat projection into the room.  Rumford’s design is the foundation of modern fireplaces.

Fireplaces in the home traditionally served as both a heat source and a location for cooking. Today those functions are performed by modern heating systems and well equipped kitchens, and the role of the fireplace is to provide a soothing ambiance, a design focal point, a social gathering place and a secondary heat source.  There are many fireplace options for the homeowner when building a new home or an addition, such as conventional masonry or high efficiency wood or gas manufactured fireplaces.  Manufactured fireplaces have increased in popularity during the past 20 to 30 years.  This increase is due to a number of reasons, including initial cost, design flexibility and style choices.

Manufactured fireplaces are also known as prefabricated or zero clearance fireplaces.  These are factory built and can be installed very close to flammable building materials such as wood wall framing or floors.  A decorative frame is installed around the outside of the firebox, and these frames are available in a variety of styles that can fit with any interior decor or style. The fireboxes and chimneys of manufactured fireplaces are designed with insulated double wall steel construction or lined with heat resistant ceramic tile.  Like all fireplaces, manufactured fireplaces require ventilation directly to the exterior, unless it is a vent free fireplace.  Wood burning fireplaces require a metal flue and vertical chimney assemblies. Gas fireplaces, if not a vent free type, can be vented through the rear or side of the unit and do not require a chimney.  All chimneys and flues must pass very strict requirements and be certified by Underwriters Laboratories with the UL label.  Manufactured fireplaces are typically sold as kits, complete systems designed by the manufacturer to be installed together. Installation should be in accordance with the manufacturer’s installation instructions and any local building codes.

When selecting a unit to purchase, the size of the firebox is an important issue.  The size of the firebox is a ratio of opening to room size.  The rule of thumb is one inch of a firebox opening width for every foot of room size.  For example, a 12'-0" x 18'-0" room has 30 ft. (12+18=30), so the firebox opening would be 30" wide.  If the firebox opening is too large, the heat in the room will go up the chimney, and if it is too small the fireplace will not adequately heat the room.

In the last few years, several innovations have been made which increase the efficiency of manufactured fireplaces.  These include glass doors, heat exchanger systems, fans, and duct work that can be connected to the housing.  Heat exchangers use vents to use outside air for combustion, thereby eliminating the use of air from inside the house.  These innovations create a fireplace that is up to 70% efficient, as compared to that of an average open masonry fireplace at 15%.

When looking at the advantages of the manufactured fireplace over conventional masonry, it is less expensive, is easier and quicker to install, has improved heat and fuel efficiency, and has flexible design capabilities. It is easy to see why this product has increased in popularity over the years.

Last modified on Tue, Sep 14, 2010
Buildipedia Staff

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