Your Fireplace – A Top Down List of Components and Their Function

Chase – Our first fireplace component is the chase. Chase is a a construction term meaning a framed space through which a flue, duct or conduit passes. The chimney chase includes the extension of the chimney above the roof line. It’s purpose is to direct heat and smoke away from the roof.
Chimney Chase Cover – Stainless or galvanized steel or aluminum cover for the chimney crown. With chimney cap, prevents rain, animal and debris intrusion.
Chimney Cap – Basically a cowled top attached to the chase cover or directly to the chimney crown or the flue if it protrudes from the chimney crown. In addition to preventing rain, animal and debris intrusion, the cap usually has an inner mesh that acts as a spark guard or arrestor. Early chimneys had no liners or flue creating the necessity for chimney sweeps. The chimney was capped with a chimney pot, usually a ceramic extension of the chimney. Today, chimney caps and pots act as extensions of the chimney and help to increase draft. A modern cap can have a turbine or electric fan, also to increase draft. A shroud can be installed over the cover and cap for aesthetic enhancement.
Chimney Crown – The top termination point of the chimney chase. A brick chimney is crowned with the mortar used to build the chimney. If the chimney chase is wood, the crown is the chase cover.
Chimney – The vertical channel that contains the flue and directs fumes and smoke up and out of your home.
Chimney Liner – A traditional brick chimney is built either without any lining or parged, which means that a layer of mortar gets troweled and smoothed onto the inside of the chimney. Clay liners come pre-cast in many sizes and shapes. One common clay liner size is 8x8x24 inches, with 24 inches the height of the liner section. Metal liners come in many sizes and shapes as well. A flexible metal liner may come in a coil which is straightened, then inserted down the flue to be fitted with the damper at the bottom and trimmed at the top, either flush or extended to accept the chimney cap. Metal liners should be insulated. Also, a liner can be poured (or cast) with liquid mortar around a bladder or movable cylinder to form a flue.
Flue – Wikipedia says that “Historically the term flue meant the chimney itself”. Also, from Dictionary.com, “smoke channel in a chimney,” 1580s, perhaps related to 15c. word meaning “mouthpiece of a hunting horn,” or perhaps from Old English flowan “to flow,” and/or Old French fluie “stream.” Confusing in today’s terminology, however, it is safe to say that a flue is the vertical shaft inside the chimney that directs heat and smoke out and away from you home. A metal chimney liner, when inserted down the chimney as a repair measure, becomes the flue. Each state and most municipalities have building codes and the size of the flue is tied to the area of the firebox opening itself.
Damper – The damper is located above the firebox and throat. It is a metal or ceramic moveable plate(s) operated by a lever or handle. Open the damper when there is a fire in the firebox to allow sufficient airflow and a cleaner burning fire. Close the damper when there is no fire in use to prevent a backflow of outside air.
Smoke Chamber – The smoke chamber is above the damper and gently reduces in size from bottom to top ending at the same size as the flue. This compresses hot air and gases from the fire, speeding up vertical flow.
Smoke Shelf – A flat or concave surface just behind the damper and toward the outside wall. It serves the dual purpose of catching ash and rain water, as well as re-curving outside air flowing down the flue, mixing it with heated air, gases and smoke from the firebox then forming a convection current that carries air, gases and smoke out the top of the flue.
The Count – Count Rumford was an American born loyalist who returned to England in 1776. In 1796 and 1798 he wrote two papers detailing his improvements to the fireplace. The Count created a shallower and taller firebox that radiated more heat into the home. The side walls tapered inward toward the back and the throat was curved, like seeing, from the outside, a ski slope from the base up, with the throat sides following the line of the firebox side walls. His design is in use today, we call it the Rumford Fireplace
Firebox – The firebox is the opening seen when viewing the fireplace from the front. This is where the fire takes place.
Throat – The throat is just above the firebox, it is behind the finishing tiles or rock and is generally unseen from the front. It’s taper, as described above, directs smoke inward and up through the smoke chamber.
Fireback – A fireback is a cast iron slab set on the back wall of the firebox. Its purpose is to protect the back wall from deterioration from extreme heat, reflect more heat into the home and retain more heat after the fire dies down. Firebacks come generally in three thicknesses, 1/2, 3/4 and one inch, for light, medium and heavy duty firebox usage. Even with the use of todays firebrick, heat from an intense fire can weaken the masonry in the firebox. The fireback should be the height and width of the firebox back wall. If the fireback is to be set on a stand or boot(s) allow about three inches in height. Firebacks are cast iron so many designs are available and can greatly enhance the ambiance of your firepace. A recent addition to the traditional fireback is the stainless steel version. These are highly heat and light reflective and are not recommended for use with gas or gas logs.
Fireplace Floor – Dictionary.com defines Hearth as “the floor of a fireplace, usually of stone, brick, etc., often extending a short distance into a room.” Therefore, fireplace floor and hearth are one in the same. Early firepits evolved into brick or stone sided fireplaces. Eventually, a hearthstone was added as the floor of the fireplace. Later, an iron plate was added under the hearthstone for better and longer lasting heat. A hearth can be level with the floor of the room or it can be raised, these can have a retainer or fender.
Hearth Extension – The part of the firebox floor that extends into the room it is in. It is usually decorative, utilizing tile, stone, brick or a non-combustible material. State and local building codes determine the minimum hearth extension size, how far out and to the sides of the fireplace face, according the the square footage of the fireplace opening.
Fireplace Screen – A metal or glass, single or three part panel placed in front of the firebox. Metal mesh can be used on either as a spark guard. Both metal and glass screens can be plain or highly decorative and prices vary widely.
Fireplace – A fireplace describes the whole structure in which a fire is utilized, from the fire box to the chimney cap, the hearth extension and face and mantle.
Fireplace Face – Finish, Surround, and Cladding are other ways to say fireplace face. I think I like “finish” best. Finish suggests completeness, including the mantle. Tile and stone are two common finishes, they can end below the mantle or extend to the ceiling. Tile or stone extended to the ceiling create a dramatic effect and can be the focal point of your home.
Mantel – Wikipedia – “The fireplace mantel or mantelpiece, also known as a chimneypiece, originated in medieval times as a hood that projected over a fire grate to catch the smoke” Look at me now! From a simple shelf to an ornate masterpiece, todays mantels can be anything that suits us individually. On top of that (no pun intended) mantel decoration and bling make for unlimited choices.
Ash Dump – We now bottom out with ash. Some fireboxes have a built in ash dump on the firebox floor. The ash dump is a door or grate that when opened allows the ash to fall into the ash pit directly below. The ash pit has a clean out door that opens in the basement or an accessible location. This is where the ash is collected and disposed of. Ash dumps seem to be very convenient, however, one drawback is in the case of a finished basement. Carpet or tile can be soiled easily if extreme care is not taken during ash removal.
Terminology – Terminology varies widely and many terms are interchangeable. Further, the above component descriptions are simple and concise and refer mostly to wood burning fireplaces. There are so many more fascinating histories and explanations out there that I recommend you do your own research, especially if you are building, renovating or re-decorating.
For further reference go to  Pa. Guild of Pro. Chimney Sweeps