Gas Fireplace Insert

Fireplace Inserts (The Ultimate In-Depth Guide With Types Explained)

In Gas Fireplaces, Indoor Fireplaces, Wood Burning Fireplaces by James O'KellyLeave a Comment

Fireplace inserts are a common way to get more out of an existing fireplace in terms of both functionality and heat output.

Traditional open fireplaces are typically not very efficient, and much of the heat produced by an open fire may not heat the room but be lost up the chimney. Open fireplaces can also lead to cold drafts between fires.

Fireplaces inserts are therefore not only a way to help improve on the downsides of having open fires, but also provide the opportunity to use a type of fireplace other than wood burning, including gas and electric.

We’ve recently removed a non-working gas fireplace insert from our kitchen fireplace, and we’re looking to possibly have a new electric fireplace insert installed within this fireplace and have done a ton of research so far on inserts.

We’ve therefore put together this guide to fireplace inserts as a complete overview to inserts to explain:

  • What a fireplace insert is, what is means and why buy an insert.
  • What the main types of fireplace insert are available to choose from.
  • How to determine what size of insert is required and whether they’re worth it.
  • And much more on everything regarding fireplace inserts.

What Is A Fireplace Insert?

A fireplace insert is a form of fireplace that can be inserted into the opening of an existing masonry fireplace to improve the functionality, heat output and aesthetics of that fireplace. A fireplace insert can be removed in the same way it was installed.

A fireplace insert is a type of fireplace that is installed to provide more features and improve the experience of using a fireplace in a home compared to using a traditional wood burning masonry fireplace.

As the name suggests, a fireplace insert is inserted into the firebox of an existing masonry fireplace through the fireplace opening.

A fireplace insert does not replace the masonry fireplace that it’s inserted into but does remove the ability to use that fireplace for open fires.

There are three main types of fireplace insert:

  • Wood burning inserts
  • Gas inserts
  • Electric inserts

Wood burning inserts help to increase the heat output from using the original wood burning fireplace, while gas fireplaces burn natural gas from a gas supply in your home and electric inserts can be plugged into a nearby standard home electrical outlet, or wired into your home electrics, to produce heat from electricity.

Wood burning and gas inserts both use a real flame to generate heat but electric fireplaces don’t have a real flame and so must produce heat using an additional built-in space heater.

We’ve discussed these main types of fireplace inserts further in this article.

We used to have a gas fireplace insert that was already installed in our kitchen fireplace when we bought the house, but we’ve since removed this gas insert when renovating our kitchen.

Gas Fireplace Insert
Our old gas fireplace insert

This gas insert wasn’t connected up to the main gas line and so we couldn’t use it, and it also made removing it easier as nothing had to be disconnected.

The insert also had a wooden surround with cast iron back panel to plug the gap between the gas fireplace and the combustible wood material (more about fireplace surrounds and clearance distances here).

Here’s how our fireplace looked once we have removed the gas insert and surround:

Gas Fireplace Insert Removed
What the original masonry fireplace looked like once we had removed our old gas fireplace insert while renovating

What Does A Fireplace Insert Do? (Why Do I Need)

A fireplace insert helps to transform an existing open wood burning fireplace into either a more efficient wood burning fireplace, or into another type of fireplace such as gas or electric.

A fireplace insert isn’t for everyone and an insert isn’t required.

We’ve left our own living room fireplace as open and don’t intend on installing an insert at this current time even through it’s a very inefficient heat source.

However, there are a number of benefits to installing and using an insert for an existing fireplace.

The benefits of a fireplace insert include:

  • Provides the opportunity to convert and use an existing wood burning fireplace into either gas or electric.
  • Provides the ability to burn wood more efficiently and effectively with potentially greater heat output when using a wood burning insert. Open masonry fireplaces are traditionally very inefficient sources of heat for a room.
  • Can help to transform an old and maybe run-down masonry fireplace into something nicer looking.
  • Help hide a disused masonry fireplace.
  • Potentially increase the value of the home.
  • Help prevent cold drafts through the fireplace from the chimney and help keep warmer air within a home for longer.

Difference Between A Fireplace & A Fireplace Insert

A fireplace typically denotes all of the main components that make up an open fireplace, including the firebox, surround and hearth. A fireplace insert is typically inserted into an open fireplace to enhance the functionality of that fireplace.

The word ‘fireplace’ can mean a lot of things but for the purpose of this article we’ll be referring to a fireplace as a traditional open wood burning fireplace, with an open firebox, hearth and surround, in which fires are built and maintained either on the floor of the firebox or within a fireplace grate.

Fireplace screens are often placed within or in front of the fireplace opening for safety purposes, and our own living room open fireplace is shown below as an example.

Fireplace Screen
An example of a traditional open fireplace, in which a fireplace insert would be installed

A fireplace insert is typically inserted into an open fireplace (like the one shown above).

The main types of fireplace inserts include wood burning, gas and electric. The insert may or may not take up the whole of the space within the fireplace firebox and an extra surround can be used to plug the gap between the insert and the opening of the fireplace.

Our old gas fireplace insert is shown below as an example of what an insert can look like.

Gas Fireplace Insert Removed
An example of a gas insert that can be put into a masonry fireplace (this is the old insert we removed)

Types Of Fireplace Insert

There are three main types of fireplace inserts available to install with open masonry fireplaces. These include:

  • Wood burning inserts
  • Gas inserts
  • Electric inserts

Wood burning fireplace inserts still allow you to burn firewood as the source of fuel as you would with a traditional open fireplace, but the efficiency of the burn and the heat output can be increased dramatically. Wood burning inserts can include both log-burning wood inserts and wood pellet inserts.

Gas fireplace inserts allow you to use your existing fireplace to burn natural gas instead of wood. A gas line will need to be installed to the fireplace for a gas insert to work.

Gas Fireplace
An example of a gas insert

Electric fireplace inserts allow you to use your standard home electrical supply to generate heat and realistic looking flames. Electric inserts must be plugged into a standard electrical outlet located within the firebox of the existing fireplace or wired directly into the home electrics.

Electric Fireplace Insert Flames
An example of an electric fireplace insert

We’ve discussed each type of fireplace insert in more detail below.

What Is A Wood Burning Fireplace Insert?

Wood burning inserts are appliances in which wood can be burnt to produce heat. A wood burning insert must be installed within a firebox and connected to the chimney flue in line with local codes and regulations.

Wood burning inserts are essentially metal boxes, typically black in color, that fit into the firebox of an existing open fireplace. The front surround of the insert lines up with the existing fireplace, and further surround can be added to close off the gap between the insert and the fireplace opening to provide a flush built-in look.

Wood Fireplace Insert
An example of a wood burning fireplace insert

Wood inserts are much like wood burning stoves but take up the whole opening of the existing fireplace rather than just sitting inside of the firebox.

While a wood insert will be placed into the firebox of an existing fireplace, a wood insert will have its own firebox where a fire is started and maintained.

They also typically have glass doors that can be closed, and controllable air vents to help regulate air flow into the insert and help increase efficiency and heat output as a result.

The Environmental Protection Agency states that traditional open fireplaces can be a low as 10% efficient, where much of the heat produced by an open fire is lost of up the chimney. Wood inserts can be much more efficient at generating heat for a home compared to open wood burning fireplaces.

Wood burning inserts can be broken down into 2 further types of inserts:

  • Wood burning inserts
  • Pellet stove inserts

Wood burning inserts are the standard type of wood insert where the traditional burning of logs occurs to produce heat.

Pellet stove inserts burn pellet fuel rather than logs and kindling, but the pellets can be made from compressed and dry bits of wood and can provide a cleaner burn with fewer emissions.

What Is A Gas Fireplace Insert?

A gas insert is a type of fireplace insert that can be installed within existing masonry fireplaces in order to generate heat and the look of a real flame in a home. A gas insert requires a supply of natural gas to burn and so a gas insert must be connected up to the household gas line when installed in order to work.

Gas inserts work much like other types of fireplace inserts in that they need to be placed within the firebox of an existing open fireplace, and the front of the insert is typically lined up with the fireplace opening.

A trim can then provided between the sides of the insert and the surrounding opening of the existing fireplace so that it looks flush and built in.

Gas Fireplace
Our gas fireplace insert

A fireplace insert must be smaller than the height, depth and width of a traditional wood burning fireplace in which it sits, otherwise it won’t fit. A smaller insert would either need to be chosen or the fireplace would need to be opening up more to provide sufficient space for an insert.

A gas insert will change your existing fireplace from wood burning to gas.

This means that a natural gas supply will now be the sole source of fuel for a gas fireplace insert. A gas fireplace cannot burn wood or use an electrical supply to generate heat.

If you’re looking to install a gas insert in your existing fireplace then you’ll need to consider how the new fireplace will be supplied with gas. A certified professional will need to install a gas line to the new gas insert.

Venting requirements will also need to be considered. Direct vent gas inserts can be the most common and the most reliable (which intake and exhaust air directly from outside), but natural vent and ventless gas insert models can also be chosen depending on the situation and personal preference.

We used to have a gas fireplace insert on our kitchen fireplace before we renovated the room and removed it.

The insert was there when we bought the house but was never connected up to our gas main (confirmed by a certified professional) and so it never worked.

This gas insert sat on the floor our granite kitchen fireplace hearth and was smaller than the opening of the existing fireplace allowing it to sit within the firebox. A cast iron back panel was used enclose the insert within the wider fireplace opening, and the whole insert and back panel was surrounded by a wooden surround and mantel.

Gas Insert With Surround
The gas fireplace insert, back panel and surround removed from our kitchen fireplace

We’re yet to decide what to replace this old gas fireplace with but we’re considering installing an electric fireplace insert, which leads us on to the final main type of fireplace insert.

What Is An Electric Fireplace Insert?

An electric insert is a type of fireplace insert that can be placed within a traditional open fireplace and uses a standard home electrical supply to generate heat and the look of flames. An electric fireplace does not burn wood or gas and the flames on an electric insert aren’t real.

Another choice of fireplace insert along with wood burning and gas inserts is electric fireplace inserts.

However, electric inserts differ from wood burning or gas inserts in that they don’t have a real flame and so the heat must be generated artificially using a form of space heater.

A downside to electric fireplace inserts is therefore that, although realistic, you don’t get real flames. On the upside there is less mess created and electric fireplaces can be easier to use as a result. See our guide on the full pros and cons of electric fireplaces for more information.

Now that we’ve removed our old gas insert from our kitchen fireplace we’re considering installing an electric fireplace insert.

Electric Fireplace Insert Installed
The electric insert we’re looking to install

As electric fireplace runs on electricity, an electrical supply will need to be installed within the firebox of the existing fireplace.

As many electric fireplace inserts come with a standard electrical plug, installing a standard home electrical outlet within the firebox of the masonry fireplace can be the best option. However, some larger more powerful electric inserts may require direct wiring the unit into the home electrics rather than plugging it in.

An electrical supply will still need to be provided to the insert, whichever method is used, as when we use our electric stove the trailing wires to the nearby outlet don’t look so good.

Electric Fireplace Power Cable
An electric insert will require an electrical fireplace to the firebox otherwise you may have wires sticking out to nearby outlets

Can I Put An Insert In My Fireplace?

The large majority of existing open fireplaces should be able to accept a wood burning, gas or electric insert. An insert is more viable for masonry fireplaces compared to pre-cast factory-built fireplaces.

There are a range of different types and sizes of fireplace inserts available to choose from to fit a whole host of differently sized fireplace fireboxes and openings.

Fireplace inserts are designed to be inserted into the traditional masonry open fireplace found in many homes. Inserts simply fit into the firebox of these existing fireplaces and where a gap is still apparent between the insert and the fireplace opening a surround can be used to make the insert look built-in. A chimney liner may also need to be installed depending on the type of insert and what has been installed already.

On the other hand, some existing open fireplaces come as pre-built units that are installed into the home as one package.

Not all factory-built fireplaces will be able to have an insert installed within them, and so you’ll need to consult the instruction manual or contact the manufacturer if you have one of these types of fireplaces.

Therefore, things to consider when seeing if you can put an insert in your own fireplace include:

  • Whether you have an open masonry fireplace or factory-built fireplace installed as one unit (the latter being less common).
  • The size of the existing fireplace opening and therefore the space available for an insert.
  • The type of insert to be installed, whether it’s wood burning, gas or electric.
  • How gas will be supplied if a gas insert it chosen, or how electricity will be supplied if an electric insert is chosen.
  • How the insert will be vented.
  • How an insert will be connected to the chimney whether a new flue liner is required.
  • What model of insert will produce the required amount of heat for the room.

Do Fireplace Inserts Produce Heat?

All wood burning and gas fireplace inserts produce heat, while the majority of electric fireplace inserts will produce heat. Certain models of electric inserts may lose the ability to generate heat in favor of more realistic flame effects.

Both wood burning and gas fireplace inserts will produce heat because fuel is being burnt using a real flame to produce heat and a visual fire experience.

Electric fireplaces do not produce any real flames. The flame effects are instead created through rotating mirrors and light to mimic the illusion of flicking flames (see more about how electric fireplaces work here).

Underneath Electric Fireplace
Electric fireplaces can’t produce heat from the flames because they’re not real and so produce heat through a form of space heater

As a result, electric fireplaces typically have an integrated form of space heater (either fan-forced or infrared) in order to generate supplementary heat. A small number of models may not have a heater and will just display the flame effects.

More efficient and larger wood burning inserts will typically be able to produce more heat (referenced in kW or BTUs) compared to smaller ones with lower efficiency ratings. Similarly, electric fireplaces with higher heat outputs can produce more heat than lower heat output ones (in Watts).

Are Fireplace Inserts More Efficient?

Fireplace inserts are typically far more efficient than the open fireplace they are replacing. Traditional masonry wood burning fireplaces are typically very inefficient sources of heat and modern inserts need to be efficient in order to meet more stringent emissions regulations.

The Environmental Protection Agency (EPA) explains that much of the heat produced by an open fire inside a home will be lost up the chimney rather than being used to heat a room, and therefore traditional open fireplace should be used primarily for aesthetic purposes rather than heating.

We’ve explained more about why open fireplaces are so inefficient here, but due to stringent emissions regulations modern inserts are designed to be as efficient as possible and can be much more efficient than an existing masonry fireplace.

Wood burning inserts are typically more efficient than open fireplaces because:

  • The air flowing to the fire can be controlled using adjustable air vents, which allows fires to burn more efficiently and produce more heat while reducing the amount of fuel used.
  • Processes such as secondary combustion can occur where more heat is extracted from every piece of wood by burning off waste gases from the initial combustion to produce even more heat.

The efficiency of wood burning fireplaces inserts will differ between each make and model. You can view the list of approved wood heaters and their official efficiency ratings on the EPA website database here.

Gas fireplace inserts can typically be far more efficient than open wood fires because there can be fewer issues with combustion of the fuel, such as the issues caused by wet wood for when burning firewood.

Electric fireplace inserts are 100% efficient because the heat is generated artificially with a space heater. Our own electric fireplace can warm up a room in our home very quickly, but the downside is that it’s not producing any real flames to enjoy.

Electric Fireplace Heater Blower
Electric fireplaces used fan heaters (shown) or infrared heaters which are far more efficient than open fires

Can You Use A Fireplace Insert Without A Fireplace?

Fireplace inserts cannot be used without an approved masonry fireplace in which to use it in. An approved masonry fireplace can be installed within in a home at a high cost to accommodate a form of insert, but better choices for fireplaces are available when an existing open fireplace is not available.

Fireplace inserts are designed to fit within the environment of an open masonry fireplace (and certain pre-fab units) where there is a sufficient firebox constructed of non-combustible materials and a sufficient chimney where a flue can be installed.

Unfortunately, without an existing open fireplace a fireplace insert isn’t much use.

However, there can be better options when it comes to choosing a fireplace when there isn’t a masonry fireplace available, and these include:

  • Wood burning stoves
  • Multi fuel stoves
  • Pellet stoves
  • Electric fireplaces

Although we’ve installed our wood burning and multi fuel stoves inside our existing open fireplaces, they can be installed in many locations around a home where suitable. A wood stove doesn’t need to be always be installed within a fireplace.

Our wood burning stove. Wood stoves can be used outside of an open fireplace if required

Similarly, pellet stoves (which use pellet fuel rather than logs) can also be installed outside of an open fireplace subject to the right conditions.

Electric fireplaces, which can come in variety of forms including wall-mounted and stoves, are perfect for use outside of an existing fireplace because there’s no real flames involved.

Electric Fireplace In Existing Fireplace
Electric fireplaces can be used wherever there is an electrical supply nearby

Does A Fireplace Insert Need A Chimney Liner?

Wood burning fireplace inserts will typically require the installation and use of a chimney liner in order for the insert to work as effectively, safely and efficient as designed. The size of chimney liner will be determined by the requirements of the particular wood burning insert.

Wood burning inserts are typically required to be connected to a flue liner of sufficient size when being installed.

The space within an existing masonry chimney will be too great for a wood burning insert and a poor draft will lead to poor burning experiences and unsafe conditions for the insert to operate. Using a wood insert without a flue can also lead to increased creosote build-up.

Although we don’t have a wood burning insert, our own wood burning stoves required the installation of stainless steel flue liner when installed within our existing open fireplaces.

A flue liner was dropped down from the top of the chimney and connected up to the stove at the bottom via the closure/register plate and the stovepipe.

A wood burning insert will need to be connected up to a flue liner just like wood stoves need to be

Expect to have to take into account the cost of a flue liner and installation when considering a wood burning fireplace insert.

Many gas fireplace inserts are direct vent, meaning that both the air required for combustion and waste air is directly vented and exhausted outside respectively. Gas fireplace therefore may not need a chimney liner.

Electric fireplaces don’t have real flames and so a chimney liner won’t be required for electric inserts because no smoke or harmful emissions are produced.

Do Fireplace Inserts Need Electricity?

Wood burning and gas inserts won’t typically require electricity in order to function but many models, particularly for wood burning inserts, will have blowers that will require an electrical supply. Electric inserts will always require a source of electricity.

Many wood burning inserts require a source of electricity in order for any integrated blowers to work, but an electrical supply will not be required to be able to start and maintain the fire itself.

Some gas fireplace inserts may need an electrical supply in order for a blower to function.

All electric inserts will require electricity in order to work.

Electric Fireplace Cable
Electric fireplace inserts will always need an electrical supply to work

Many wood burning inserts and some gas inserts will therefore require an electrical supply, while all electric inserts will need electricity to work.

Power can be provided by a nearby standard home electrical outlet, either on a nearby wall of within the firebox of the existing masonry fireplace itself (if building regulations allow). Direct wiring into the home electrics is also possible for certain models of electric fireplace.

Are Fireplace Inserts Worth It?

Fireplace inserts can be worth it when used over a long period of time. Although the initial cost of purchase and installation of an insert and any required accessories such as flue liners can be high, a fireplace insert can help to increase heat output and reduce heating and fuel costs over time.

Fireplace inserts should be considered as long-term investments for you and your home.

The cost of inserts can be quite high depending on the type of insert, size required and installation requirements.

However, open masonry fireplaces are traditionally very inefficient sources of heat and an insert can dramatically increase the amount of heat produced when burning firewood. Gas and electric inserts can also generate a lot more heat compared to open fires.

The initial costs of installing a fireplace insert should be weighed up against the long term benefits.

Initial costs can include:

  • Purchase and delivery of the fireplace insert.
  • Professional installation of the insert.
  • Purchase and installation of any flue liners or vents required.
  • Installation of an electrical supply to the insert, if required.
  • Installation of a gas supply to the insert, if required.

These costs should be compared to the longer term benefits and cost savings, which can include:

  • A typically large and noticeable difference in the efficiency and heat output from the new insert compared to the original open fireplace.
  • Potentially reduced fuel usage, such as burning through fewer logs.
  • A more pleasant fireplace experience.
  • Less mess and maintenance of fires compared to open fires.
  • Potentially increased home value.

In the majority of cases, it can be worth it to install a fireplace insert. Fireplace inserts are a very popular form of fireplace and can help to transform your old, inefficient masonry fireplaces into something that will bring plenty of warmth and joy to your home.

How Do Fireplace Inserts Work?

Fireplace inserts work by fitting into the firebox of an existing fireplace and using the existing setup to be able to generate heat more efficiently compared to what is possible with open masonry fireplaces.

Wood burning, gas and electric fireplace inserts all work differently from each other. We’ve explained more about how each works below.

How Wood Burning Inserts Work

Wood burning inserts work by creating a more sealed environment with better control over air flow to the fire to help generate more heat compared to an open fire.

Wood inserts sit within the firebox of an open fireplace and require a connection to the top of the existing chimney using a flue liner of the correct length and size.

Air flows into the insert firebox through the air vents, which can be controllable and allow the user to help manage the fire inside more effectively. Reducing the airflow to the wood burning insert will help to slow the fire down and allow it to burn the logs more efficiently to produce more heat than what is possible with an open fire.

Many wood fireplace inserts also have blowers which help to spread the heat around the room or home.

How Gas Inserts Work

Gas fireplace inserts work by taking air either from within the room or outside, depending on the model and venting setup, and burn through a supply of gas that is connected up to the main gas line for the house.

Fumes can be exhausted out through the wall or up the chimney, again depending on the setup.

How Electric Inserts Work

Electric fireplace inserts work by using the standard home electrical supply to generate the look of flames and produce heat through a form of integrated space heater, such as fan forced or infrared.

Electric fireplaces don’t have real flames and so the flame effects need to be produced by reflecting light off rotating mirrors.

For more information we’ve explained exactly how an electric fireplace works here.

How Long Do Fireplace Inserts Last?

Fireplace inserts can last for many years or decades depending how often and how well they are used.

Wood burning and gas inserts will typically last longer than electric inserts because there’s fewer moving parts and electrical components (less that can go wrong), but on the other hand are typically more expensive to buy and install.

You might also find that there are longer warranties on wood burning or gas inserts compared to electric inserts. Electric fireplaces typically carry a 1 or 2 year warranty period, while wood burning appliances can have 5 or even 10 year warranties.

Can Fireplace Inserts Be Removed Or Replaced?

All fireplace inserts can typically be removed and replaced in the same way that they were first installed. Converting a fireplace insert back to an open wood burning fireplaces may require the removal of any electrical of gas supply to the insert.

Fireplace inserts can typically be removed in the reverse order process in which they were originally installed.

Fireplace insert appliances can last for a long period of time but won’t last forever. An insert may need to be replaced if no longer working, or may need to be removed altogether to open the original masonry fireplace back up again.

Certain elements may need to have been originally provided to the fireplace to allow the insert to function. These could include:

  • A flue liner for a wood burning insert.
  • A gas line to serve a gas fireplace insert.
  • An electrical supply to serve an electric fireplace insert.

With the surrounding infrastructure already set up it can be easier to replace an insert.

It’s still possible to remove a fireplace insert altogether, but the above may also need to be considered for removal if you’re planning on returning an insert back to the original open wood burning fireplace.

How Much Do Fireplace Inserts Cost?

Wood burning inserts and gas fireplace inserts typically cost around $2,000 with costs ranging from $1,000 to $3,000 on average. Electric fireplace inserts can range from a few hundred dollars to $2,000+ but expect to pay around $1,000.

The cost of a fireplace insert will vary depending on:

  • The type of insert; wood burning gas or electric
  • The brand and model of insert
  • Size of unit
  • Heat output required to heat room adequately

These factors affect the cost of the unit itself. Further costs can come with both installation and additional components required to make the insert work.

Additional costs can be:

  • Flue liner installation and connection for wood burning inserts.
  • Gas line to the fireplace for gas fireplace inserts.
  • Electrical supply to the fireplace for electric inserts, but also for any wood burning inserts that require a source of electricity for any integrate blower to work.

Further Reading

A Complete Guide To Electric Fireplace Inserts

Parts Of A Fireplace & Chimney Explained

A Complete Guide To Fireplace Fireboxes

A Complete Guide To Fireplace Hearths

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