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    Parts of a Fireplace: Gas Fireplace Parts You Should Know

    Shopping and searching for the right gas fireplace is not easy. There are countless variations with too many styles to name. And then there are brands, a ton of brands. There are so many options it can be paralyzing. But for now, today, let's talk about gas fireplaces. Let's breakdown the very basics when shopping for or learning about a gas fireplace.

    3-sided fireplace frame

    Gas fireplaces are exceptional heating appliances. They run on propane or natural gas, rather than wood. We know all too well that wood burning fireplaces require a lot of work: sourcing or gathering wood, seasoning the wood, and storing it! With gas, all you have to do is turn a valve and press a button. It's really that simple, which explains their growing popularity among consumers.

    To remain competitive and compliant with industry regulations, many fireplace manufacturers equip gas models with top-quality components. There's nothing to argue with here; except, many people don't know what these parts are called or how to use them.

    Considering that most fireplace parts are essential to the safe operation and functioning of these units, it's equally important that people with a gas fireplace know what these parts are and how to use them properly.

    No matter how complex fireplace parts may seem, most gas fireplace models share similar parts and accessory options. In this article, we will show you each of those parts and explain what they do. By the time you're done, you'll have a basic understanding of the most common gas fireplace components and accessories.

    To make it even easier, this article contains a neat interactive guide at the end to help you see where each of the main parts is located. But, first thing's first. We'll start with the exterior parts of your fireplace and work our way to the interior components and accessories.

    The Hearth

    When most people first look at a fireplace, their eyes naturally gravitate toward the box that houses the flames. This cavernous area is called the firebox. Yet, the firebox works in tandem with an important base made from fireproof material called a hearth. Gas fireplaces, like traditional wood burning fireplaces, are constructed with a protective hearth.

    4-sided stainless steel frame

    In prefabricated fireplace models, the hearth is usually metal and features a decorative overlay. This overlay can be a cement fireplace liner with a brick pattern, a porcelain-coated liner, or another decorative material.

    For masonry fireplaces, the hearth is typically built from bricks and extends outward from the firebox with two configuration options — raised or flat.

    Raised hearths sit on a platform a few inches above the floor. A raised hearth is perfect to sit on or place decorations. Flat hearths are flush with the floor. These give you more room for furniture and are less costly to build than a raised hearth.

    In gas-burning built-in models, the hearth is less functional. However, any sufficiently sized masonry wood burning fireplace can be converted to gas. Take a fireplace insert or a gas burner, for instance.

    In either of these cases, the hearth encloses the base of the firebox and serves as an attachment point for a gas fireplace burnerfaux log grate, and other components a gas fireplace may use.

    Gas fireplace burner

    Direct vent and vent free gas burning fireplaces will use the hearth as a sort of raised platform. On the surface, the gas tube, pan, or ribbon burner will be mounted to support brackets. A gas fireplace burner will have a gas supply tube or line that routes into the base of the burner.

    Affixed to the end of the supply tube is where you'll find a part called a venturi or air mixer. This part is responsible for drawing combustion air for the burner. It usually overlaps what is known as a burner orifice, which is a small fitting with an appropriately sized hole to support the flow of natural gas or propane fuels.

    In gas burning applications, the burner orifice is usually just above the hearth, with the fireplace gas valve control, module controls, and transformer mounted below the hearth for protection from the heat.

    A peek inside a gas fireplace

    As you can see, the hearth serves as a protective heat shield for many components within and near the fireplace. To disguise the bland exterior appearance of the hearth for a gas fireplace, many people add some type of decorative fireplace front.

    Fireplace Fronts

    While the fire is the star of the show, it's the outside of the fireplace that ties the room together. That's why many modern prefabricated fireplaces have many decorative front options.

    Gas fireplaces offer a wealth of different options to help them fit in with the room décor. Decorative fireplace fronts, surrounds, and overlays are metal frames that flank the fireplace opening. These accessories cover any gaps in the wall from installation and look great.

    Prefabricated fireplaces have a metal weldment or front that can be directly covered (excluding any louvers or grilles), by tile, stone, brick, or metal.

    Fireplace facing

    If finished with brick, the fireplace facade or facing can make it difficult to tell the difference between a masonry fireplace and a prefabricated model. Only a closer investigation of the firebox will tell the difference.

    As far as safety is concerned, you'll find a tempered or ceramic glass door assembly seals off most gas fireplaces from the room. The door is usually fixed to a mounting rail and closed by a glass latch assembly.

    Real Fyre 4-sided fireplace surround

    Direct vent gas fireplaces offer several safety features. A removable fireplace barrier screen covers the glass door to guard against contact with the hot glass. They also use pressure relief baffles that help mitigate damage to the glass if the unit suffers a delayed ignition. If you have a B-vent fireplace, however, you will have an open-faced firebox similar to the look of a traditional wood burning fireplace.

    Firebox

    Let's move inside the fireplace now to where the action happens - the firebox. For both wood burning and gas burning fireplaces, remember the term firebox applies to the enclosed area where the fire burns. So to review, the hearth is what the firebox sits on, typically the fireproof base underneath the fireplace box.

    Breckenridge Vent Free Gas Firebox

    The firebox of a gas fireplace is simply a combustion chamber where the fire ignites. It includes a floor, sides, and a top lined with firebrick or ceramic liner to encase the flames. The term firebox more readily applies to vent-free gas appliances that do not come with a gas burner as standard, meaning they are "just a box" instead of a fireplace.

    The beauty of gas fireplaces stems from the range of available styles and the customization options you have to make them your own.

    Gas Fireplace Media

    The outside of a fireplace is customizable and the inside is too! Direct vent fireplaces can use many different media options to get your desired look. It is common to see a ceramic or refractory gas fireplace log set, fire glass, and decorative fire media or art.

    Assorted gas fireplace media

    It's worth noting that some direct vent fireplaces come designed for one type of media while other fireplaces can be adapted to accommodate a fireplace grate or purpose-built media tray or pan. But, customization doesn't stop here.

    Fireplace Liners

    The walls of your firebox should look good as well. This decorative part is called a liner. Both prefabricated wood-burning and gas models use liners. Gas or ethanol models use lightweight ceramic liners or porcelain-coated reflective liners. Gas fireplace liners make the fire look incredible! They also protect the firebox from the flames and help radiate heat back into the home.

    Gas firebox liner

    Where masonry fireplaces rely on the firebrick to provide structural integrity to the fireplace, prefabricated fireplaces rely on an inner wrapper. The inner wrapper is often hidden from view behind the liners in a prefabricated wood burning fireplace. The wrapper is a heavy gauge sheet metal or plate steel assembly that ties the firebox together and gives it both shape and strength.

    The inner and outer prefabricated fireplace wrapper

    For prefabricated fireplaces of all fuel types, there is some sort of air space that is designed to surround the backside of the inner wrapper. This serves as a cooling zone to dissipate heat, allowing the outer surface of most prefabricated models to touch adjacent wood framing. This is where the term zero clearance fireplace originates from.

    For prefabricated fireplaces, there is also a gas line conduit that bridges the gap between the inner and outer wrapper, protecting the gas line and guiding it to purpose-built gas line knockouts made into the brick liners or panels.

    Gas firebox knockout wall

    Since gas fireplaces emit lower temperatures, the inner wrapper consists of the back and sidewalls of the firebox. These interior walls are often painted matte black. But, you can add ceramic or porcelain liners to cover the walls for a more upscale appearance.

    Gas Fireplace Venting

    If you were to look up inside the firebox, you will see your venting system. Venting systems are not a one-size-fits-all solution. The heating appliance you have will determine the type of venting system you need. Since we are talking about gas fireplaces, let's go over a couple of the different systems you'll encounter online.

    Direct Vent Fireplaces

    Direct vent fireplaces use some unique technology not associated with other gas fireplaces. For starters, they don't use any combustion air from the home to operate. Instead, they use a coaxial venting system with an inner and outer collar. This venting system resembles a double-walled chimney system used for a wood burning fireplace, which also has two pipes.

    Vented gas fireplace

    In a direct vent fireplace, there's a small inner pipe that carries exhaust gases to the outdoors, while a larger outer pipe draws in combustion air for the unit to operate. Direct-vent units are much more efficient than B-vent fireplaces, as they come with a glass front to prevent room air interference. Most models even come with a protective barrier screen to install against the glass front, which protects against unwanted burns.

    B-Vent Gas Fireplaces

    B-vent gas fireplaces are the middle ground between direct vent and vent free. They vent like a direct vent fireplace but open to the room like a vent free fireplace. They offer a realistic flame appearance and are simple to use. B-vent fireplaces use type-B vent pipe and vent vertically like a wood burning fireplace.

    B-vent gas fireplace

    Because of this verticality, they use a downdraft baffle to prevent blowout of the pilot if there's a downdraft from the chimney. They will also include mesh screens like vent-free or wood-burning models. One thing to keep in mind with this venting system is heat loss. B-vent fireplaces tend to lose a lot of heat through the chimney, so we highly recommend using a blower with these models to increase heating performance.

    Vent Free Gas Fireplaces

    Vent free gas fireplaces do not use a venting system at all, but they emit more heat than a wood burning high-efficiency fireplace. They are able to do this by limiting their BTU output and by using a unique high-efficiency burner system. Available in both standing pilot and intermittent pilot (IPI) versions, their pilot assembly uses a special oxygen depletion sensor to ensure the fireplace shuts down if oxygen levels in the room get to low.

    Oxygen depletion sensor

    Because vent-free fireplaces rely on room air for combustion, they are open to the room. They will often include a screen for safety. If you're looking for ways to extend the heating capability of your fireplace, it's always a wise decision to look for compatible fireplace blowers.

    Fireplace Blower and Fan

    Virtually every style or model of fireplace offers the use of a blower. Fireplace blowers circulate the heated air from your fireplace throughout your living space. A lot of heat from the fireplace can escape into the vents. Blowers prevent this.

    Fireplace blower

    Masonry fireplaces are rarely built with blowers, but there are still some models built with fans. Older versions would usually feature ductwork embedded within the brick or stone with intake ducts near the floor and outputs near the ceiling. Inline fans are installed at the input or output of the ducts. Other versions would use a complete metal box with built-in heat exchanger tubes that are heated directly by the fire.

    Prefabricated wood burning fireplaces, direct vent gas fireplaces, vent free gas fireplaces, and electric fireplaces will often use a rotary style blower, also called a squirrel cage blower. This blower fits at the very bottom of the fireplace. It pulls room air through the base of the fireplace, forcing it around the back of the heater and to the top of the unit.

    It's difficult to discuss venting components without discussing some pretty important parts of your chimney as well.

    Chimney Parts

    Chimney systems for both masonry and prefabricated gas fireplaces serve the same purpose. They take the rising smoke and heat from the fire and act as a conduit to exhaust these byproducts to the outdoors. For masonry fireplaces, this is commonly done either via clay flue tiles (individual fire clay tiles that are stacked, mortared together, and then encased in brick or stone) or via a metal liner consisting of overlapping sections.

    Prefabricated fireplaces instead use a double or triple walled metal chimney. The chimney sections usually snap or twist together one by one until reaching the required height.

    Masonry chimneys are their own support structure, with the brick or stone encasement doing the work. Prefabricated chimney systems offer a wealth of support components and insulative parts to keep the chimney a minimum distance from insulation or combustible framing. Both types of systems feature a chimney cap that is designed to contain sparks, keep out pests, cut down on wind-related downdrafts, and limit the amount of rain or snow that can enter the chimney.

    Chimney cap

    Prefabricated fireplaces may have their chimney pipe enclosed within a framed “false” chimney structure known as a chase. To keep out rain and seal the chase, a metal chase pan or shroud is used to cover the area between the chimney pipe and the outer structure of the chase. Masonry fireplace chimneys are instead finished out with a masonry wash, which is a sloped cement surface that tapers away from the flue tiles and toward the outside of the chimney, allowing rain or snow to drain away.

    Fireplace Ignition Systems

    After exploring everything in and around the fireplace, it's now time to talk about what makes the fire — the ignition system.

    Gas fireplaces have a burner and various other components that come as standard. Some of those components sit right on the hearth of the fireplace. All gas fireplaces will use some ignition system to light their burners. Direct vent gas systems and B-vent systems use a millivolt or standing pilot, a direct ignition system, or an intermittent pilot system.

    We provide more in-depth information pertaining to the way each ignition system operates below:

    • Millivolt Ignition System: A millivolt or standing pilot system uses a pilot assembly that consists of a pilot supply tube to carry gas for the pilot flame, as well as a thermocouple or thermopile or both. The thermocouple and thermopiles are small thermal generators. The pilot flame engulfs them and the thermal expansion that results generates a small amount of electricity, which the gas valve then uses to operate. A millivolt pilot system is usually manually lit by depressing a control button on the gas valve while simultaneously using a push-button ignitor to ignite the pilot flame.
    Gas fireplace push-button ignition
    • Direct Ignition System: Direct ignition systems, though rare to find in more modern gas fireplaces, use a spark ignitor instead of a standing pilot. The spark ignitor is a simple electrode that generates a strong spark via voltage supplied by a control module. The spark lights the gas being released from the burner and once lit, the flames from the burner heat a flame rectifier that is part of the ignitor. The flame rectifier sends a signal back to the control module to tell it that flame is present. If the flame is lost, the signal will cease and the control module will close the gas valve.
    • Intermittent Pilot System: The intermittent pilot or IPI system is like a combination of the millivolt system and the direct ignition system. The system has a pilot light, but it only lights when the unit is preparing to activate. The control module in the unit detects an input via a wall switch or remote control to turn on, the control module in the unit sends a signal to the gas valve, and gas then flows to the pilot assembly while an ignitor begins to fire. Once the pilot flame lights and is stable, the main burner will light. A flame rectifier detects the flame while the unit operates. If the control module receives an “off” command, both the pilot flame and the main burner will shut down. The lack of standing pilot saves on fuel costs.
    Blue flame on gas pilot

    While each of these ignition systems works differently, they all give you the same result, a warm and inviting fire. But if you really want to make your fireplace special, we recommend you add some optional fireplace accessories.

    Fireplace Accessories

    Optional fireplace accessories give your fireplace that little extra something, making it more convenient and aesthetically appealing than ever. While decorative media serves as a common way to customize your unit, adding special controls or light kits can do wonders for your unit.

    Controls

    Gas fireplaces offer many flame control options. Wall switches, handheld remote controls, and even control via Bluetooth syncing. These are all possibilities.

    Fireplace handheld remote control

    Flame height is adjustable either manually or by the use of an electric stepper motor. Some units will come with the electric motor as standard, while others can have it added as an option.

    Light Kits

    Direct vent, B-vent, and vent free gas fireplaces may also offer an ambient light kit that fits within the firebox to accent the unit. These light kits are shielded against the heat via thick lenses or housings.

    Those are just a couple of the fireplace accessories available to you. There are many more out there like fireplace doors, fireplace screens, and toolsets that we did not mention in this article. Click here to see other fireplace accessories that will give your gas fireplace a personalized touch.

    How Well Do You Know Your Gas Fireplace Parts?

    Now that you know some of the most important parts of a gas fireplace, you're ready to explore the wide variety of gas fireplaces out there with new knowledge to guide you. If you have any questions or concerns, do not hesitate to call one of our NFI certified technicians at 1-800-203-1642.

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    About the Author

    Dr. Angela Martin

    With an extensive background in advanced technical writing and academic research, Angela is our Content Editor and Project Manager. She currently supervises article production for our eFireplacestore and eCanopy brands.

    Outside of work, she is actively involved in her sorority and engages in educational consulting, dissertation mentoring, and social advocacy. When she manages to get downtime, she enjoys vacationing at the beach and spending time with family and friends.

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