Parts of a Fireplace: Gas Fireplace Parts You Should Know
Shopping and searching for the right gas fireplace can
be challenging. 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, let's break down the basics when shopping for or
learning about a gas fireplace.
Gas fireplaces and gas fireplace inserts 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 it, and storing it! All you have to do with gas is turn a valve and press a button. It's that simple, which explains their growing popularity among consumers.
Many fireplace manufacturers equip gas models with top-quality components to remain competitive and compliant with industry regulations. 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 these units' safe operation and functioning, 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. You'll understand the most common gas fireplace components and accessories by the end.
This article contains a neat interactive guide to help you locate each main part. We'll start with the exterior parts of your fireplace and work our way to the interior components and accessories.
When most people first look at a fireplace, their eyes naturally gravitate toward the box that houses the flames. This hollow area is called the firebox. The firebox works with an important base made from fireproof material called a hearth. Like traditional wood-burning fireplaces, gas fireplaces are constructed with a protective hearth.
- 4-sided stainless steel frame
The hearth is usually metal in prefabricated fireplace models 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.
The hearth for masonry fireplaces 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, you can convert any sufficiently sized masonry wood-burning fireplace to gas. Take a propane gas fireplace insert or a gas burner, for instance.
- Gas fireplace burner
Direct vent and vent-free gas-burning fireplaces will use the hearth as a raised platform. The gas tube, pan, or ribbon burner will be mounted on the surface 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. Many people add some decorative fireplace front to disguise the bland exterior appearance of the hearth for a gas fireplace.
While the fire is the star of the show, the outside of the fireplace ties the room together. That's why many modern prefabricated fireplaces have many decorative front options.
Gas fireplaces offer many 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 louvers or grilles) by tile, stone, brick, or metal. If finished with brick, the fireplace façade or facing can make distinguishing between a masonry fireplace and a prefabricated model difficult. Only a closer investigation of the firebox will tell the difference.
- 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.
Regarding safety, 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
Let's move inside the fireplace 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. The firebox sits on the hearth, 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 without 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 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 are designed for one type of media while others can be adapted to accommodate a fireplace grate or purpose-built media tray or pan. But customization doesn't stop here.
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 while also protecting 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 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 shape and strength
- The inner and outer prefabricated fireplace wrapper
Prefabricated fireplaces of all fuel types are designed to leave some air space to surround the backside of the inner wrapper. The air space 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.
A gas line conduit bridges the gap between the inner and outer wrapper for prefabricated fireplaces. It protects and guides the gas line to purpose-built knockouts made into 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 would see your venting system. Venting systems are not a one-size-fits-all solution. Your heating appliance will determine the type of venting system you need. Since we are talking about gas fireplaces, we'll review several 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 with two pipes.
- Vented gas fireplace
A direct vent fireplace has 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 have a glass front to prevent room air interference. Most models even have a protective barrier screen to install against the glass front, protecting 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 but emit more heat than a wood-burning high-efficiency fireplace. They can limit their BTU output and use a unique high-efficiency burner system. Available in both standing 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 too low.
- Oxygen depletion sensor
Because vent-free fireplaces rely on room air for combustion, they are open to the room and 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, from traditional fireplaces to double-sided gas fireplace inserts. 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 help prevent this. Even an outdoor gas fireplace insert with blowers can benefit from the improved circulation.
- Fireplace blower
Masonry fireplaces with blowers are rare, but you can still find some models built with fans. Older versions 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 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 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 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. Masonry fireplaces do this via clay flue tiles (individual fire clay tiles stacked, mortared together, and then encased in brick or stone) or 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 systems feature a chimney cap 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 frame chimney structure known as a chase. A metal chase pan or shroud can cover the area between the chimney pipe and the outer structure of the chase. Masonry fireplace chimneys are finished with a masonry wash, 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 time to discuss 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 and B-vent systems use a millivolt or standing pilot, direct ignition, or intermittent pilot systems.
We provide more in-depth information about the way each ignition system operates below:
- Millivolt Ignition System: A millivolt or standing pilot system uses a pilot assembly consisting of a pilot supply tube to carry gas for the pilot flame, a thermocouple, thermopile, or both. The thermocouple and thermopiles are small thermal generators. The pilot flame engulfs them, and the thermal expansion 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 using a push-button ignitor to ignite the pilot flame.
- Gas fireplace push-button ignition
- Direct Ignition System: Though rare in more modern gas fireplaces, direct ignition systems 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 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 to the control module to tell it that the 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 the middle ground between the millivolt and direct ignition systems. The system has a pilot light but 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 and 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, the pilot flame and the main burner will shut down. The lack of a standing pilot saves on fuel costs.
- Blue flame on gas pilot
While these ignition systems work differently, they all give you the same result: a warm and inviting fire. But if you want to make your fireplace special, we recommend adding some optional fireplace accessories.
Optional accessories give your fireplace that little extra something, making it more convenient and aesthetically appealing than ever. While decorative media is a common way to customize your unit, adding special controls or light kits can do wonders for your unit.
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 manually or by using an electric stepper motor. Some units will come with the electric motor as standard, while others can add it as an option.
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. Thick lenses or housings shield these light kits against heat.
Those are just a couple of the fireplace accessories available to you. Many more are out there, like fireplace doors, screens, and tools, to name a few. Click here for other accessories to 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.