Important Parts of a Fireplace That You Should Know
Family, warmth, survival, security, and safety - these are all what traditional fireplaces symbolize. From ancient fire pits to today's manufactured electric and gas fireplaces, technology has come a long way. But what makes a traditional fireplace function? We are going to look at the various parts of a fireplace and learn how they work together to form a more complex structure than you might think.
One of the first major improvements to fireplace technology was in 1678, when Prince Rupert, nephew of Charles I, raised the grate of the fireplace, improving the airflow and venting system. Later, in the 18th century, Benjamin Franklin developed a convection chamber for the fireplace that improved the efficiency of fireplaces and wood stoves. He also improved the airflow by pulling air from a basement and venting out a longer area at the top.
A Smoky Past
Before traditional fireplaces became commonplace, ancient fire pits attempted the same heating effect and were sometimes built in the ground, within caves, or in the center of a hut or dwelling. The disadvantage of early indoor fire pits was that they produced toxic and/or irritating smoke inside the dwelling. Evidence of prehistoric, man-made fires exists on all five inhabited continents.
Fire pits developed into raised hearths in buildings, but venting smoke depended on open windows or holes in roofs. The medieval great hall typically had a centrally located hearth, where an open fire burned with the smoke rising to the vent in the roof. Louvers were developed during the Middle Ages to allow the roof vents to be covered so rain and snow would not enter.
Also during the Middle Ages, smoke canopies were invented to prevent smoke from spreading through a room and vent it out through a wall or roof. These could be placed against stone walls, instead of taking up the middle of the room, and this allowed smaller rooms to be heated.
A traditional fireplace is a structure made of brick, stone, or metal, designed to contain a fire. Historically, traditional fireplaces were used to heat a dwelling to cook and to heat water (for both laundry and domestic uses).
The Parts of a Fireplace
The Chimney Passage
Parts of a Fireplace
For any fireplace owner, or those thinking of adding a traditional fireplace to their home, it is important to understand the anatomy of a fireplace, how it functions, and the upkeep it might require. There are over twenty parts of a fireplace which work together to heat and ventilate. We will review in more detail below the parts of a fireplace and the parts of a chimney.
Made of heavy-duty brick or cinder block, the foundation provides the structural support for the chimney's walls. It should be made to withstand high levels of heat.
Typically made of concrete, the footing is the surface under the ash pit or the firebox (if the home does not have an ash pit).
The Outer Hearth
The outer hearth, or hearth extension, is the area in front of the inner hearth that extends into the room. The outer hearth is specially designed with fire-resistant materials (like brick or tile) to reduce the risk of a fire.
The Inner Hearth
Aptly named, the inner hearth is the inner portion of the outer hearth. Tucked just inside the opening, it is the actual floor of the fireplace. Also known as the firebox, it is lined with firebrick, a special brick made from fire clay that can withstand a fire's high temperatures.
Firebrick can crack or weaken after years of use, so fireboxes should be inspected about every five years. Common issues that arise within the firebox or inner hearth usually are related to heat damage, water damage, or incorrect dimensions.
History Behind the Firebox
In the later 18th century, Count Rumford designed a fireplace with a tall, shallow firebox that was better at drawing the smoke up and out of the building. The shallow design also improved the amount of radiant heat projected into the room. Rumford's design is the foundation for modern fireplaces.
The fireplace face (or “surround”) is the part of the fireplace surrounding the firebox that can be seen in the room. It's made of brick, stone, concrete, or other noncombustible materials. Its purpose is to ensure the area outside the inner hearth doesn't catch fire.
Some fireplaces have doors made of glass or metal that prevent air from transferring between the flue and room. They shut off the air flow when the fire has died down or the fireplace is not in use.
This is the decorative shelf above the fireplace. Originally, it helped redirect the smoke and keep it from entering the room.
Beneath the smoke shelf is the damper, a movable covering that separates the firebox from the space above. There may also be a chimney damper, which is operated by a cable and closes the chimney at the top to eliminate downdrafts.
Every time a fireplace is in use, the damper should be open. It can be closed when the fireplace is not in use to prevent water, animals, or a draft from entering the house.
The throat damper is located in the fireplace's throat, above the inner hearth. New requirements state that the throat should be 8-inches or more above the fireplace opening; previous requirements were only 6-inches.
The smoke chamber connects the fireplace and the flue. At the bottom of the smoke chamber is the smoke shelf, which deflects downdrafts and prevents any rain or soot from dropping directly into the fireplace.
The smoke chamber has sloping walls to help compress the byproducts of combustion as they move up the flue, without causing a backdraft.
This is an opening in the firebox that enables the ash to fall into the ash pit. The ash dump may have an ash dump door which can open to dump the ash.
Generally located in the basement or under the firebox, the ash pit is an area where the ash collects. Some fireplaces may not have an ash pit, in which case, the ash would be cleaned directly from the firebox.
The ash pit may also have a cleanout door, located in the basement or outside at the base of the chimney, allowing the homeowner to gain access to the enclosed ash pit.
Parts of the Chimney Passage
Now that you know the parts of a fireplace, let's look at the parts of the chimney passage.
A chimney is a masonry structure that passes through a house and encloses the flue. Chimneys were invented in northern Europe in the 11th or 12th century and largely fixed the problem of fumes, more reliably venting smoke outside.
Chimneys made it possible to give the fireplace a draft and also made it possible to put fireplaces in multiple rooms in buildings conveniently. They did not come into general use immediately, however, as they were expensive to build and maintain.
The chimney crown is the concrete or mortar top that seals the top edge of the masonry chimney. It helps keep water out of the bricks and mortar of the chimney, protecting them from damage.
The chimney cap (also known as a rain cover) is similar to the chimney crown.
Since the chimney crown is located on the top of the chimney, it is common for it to break or become dysfunctional without a homeowner's knowledge.
A chimney cap is the cheapest way to protect the fireplace; otherwise, water, snow, debris, and other elements can enter the chimney interior freely.
The spark arrester is a metal mesh that fits over the top of the flue and prevents the escaping gases from carrying burning materials onto the roof. A chimney cap prevents moisture and animals from entering the flue. It may rotate to block wind gusts.
It is important to make sure the parts of a fireplace are all working properly. The first few times you ignite your fireplace every winter are when there is the greatest risk for issues. Have your chimney inspected and cleaned before the start of winter.
After ages of using the same method of heating technology (the ancient fire pit), in a few short centuries, our heating technology greatly improved, and soon lead to the making of the traditional fireplace. As a structure that has long been integral in representing comfort, warmth, family, and so much more, the traditional fireplace has always felt deceivingly simple in design.
However, we have learned that there are several parts of a fireplace that work together to create the comfortable crackling fire that we have all come to enjoy.