How to Install a Wood Stove in a Fireplace

Written by: Jamie

Updated on: March 14, 2022

If you're lucky enough to have an existing fireplace in your home then installing a wood stove is a much more heat efficient option that's open to you. We explain how it's done in our in-depth guide.

Wood stove installed in fireplace

Fireplaces may look great but the truth is they are a dated and very inefficient method of heating.

Studies have shown that fireplaces need 4-10 as much wood to generate the same amount of heat as a modern wood stove.

You can transform the fuel efficiency of your fireplace and improve the air quality of your front room dramatically by switching to a wood burning stove.

You can do this and all the while retain all of its character and charm too.

In this guide, we explain the steps you need to follow to achieve a safe and efficient installation. 


Checklist: Converting a Fireplace to a Wood Stove

There are a few boxes to tick before you even think about shopping for an efficient wood stove for your fireplace.

You're off to a good start if you already have a sizeable fireplace but there are some important details to check out before you go any further.

We go into each one in detail following the list.

  • Positioning is key  
  • Is your hearth suitable?
  • Clearances to combustibles
  • The type of chimney
  • Size and diameter of the flue
  • Ventilation of the room
  • The size of the wood burner
  • Check local regulations


Positioning is Key

A lot of the following points we make regarding installation include measurements taken from where your wood stove is positioned.

I think it's important to clarify the options you have as early on as possible. This will help make the rest of our installation guide as easy to understand as possible.

I know most people like their wood stoves to be positioned inside the fireplace and this is the ideal situation.

This allows a straight flue to extend from the top of the stove which removes exhaust gases more efficiently than a flue with bends. It's also a better use of space.

However, this isn't always possible and you may find you might need to rethink installation after going through our pre-installation checklist.

Having a fireplace that is too small to accommodate a big enough wood stove to heat your room is a common issue.

Your other option is to have the stove positioned in front of the fireplace on an extended hearth.

The flue pipe then extends from the top or the back of the wood stove.

The flue then enters the chimney through the existing opening (which is then sealed around the flue) or a new opening is made in the wall above the damper.


Is Your Hearth Suitable?

Safety regulations dictate that your hearth meets certain standards when being used for a wood stove installation.

These MUST be adhered to if you want a legal installation. Here's the basic checklist:

  1. The hearth must have a minimum of 30cm clearance to from the front of the stove. Do you need to extend your hearth?
  2. It also must extend by 15cm at each side.
  3. It should be made from a non-combustible material (this one shouldn't be a problem)
  4. Make sure there are no cracks or holes
  5. It needs to be at least 1.2cm thick (or at least 2.5cm for temperatures more than 212 Fahrenheit.


Clearances to Combustibles

Wood stoves come with specific clearance distances to walls and also to combustible materials.

These values vary from model to model and they should be clearly stated in the fact sheets before you buy. If your fireplace has been used in recent times then there won't be any legal restrictions on the distance a wood stove needs to be from the fireplace walls.

As long as the fireplace is made from stone or brick (or some other non combustible material) then it can handle the heat output that a wood burning stove is going to throw at it.

It's always best to stick to stated clearances if possible however (despite using a fireplace), as they allow for the most efficient circulation of heat and air. You also want enough room to be able to clean and maintain the stove as necessary.

You must make sure that there is adequate distance from any flammable materials. Materials like wallpaper are particularly dangerous when too close to a stove.

Be sure to check the stove manuals and leave a bit of slack in your measurements when planning.

Actions:

  1. Take measurements of your fireplace to make sure it can contain a wood stove and maintain minimum clearance distances too.
  2. Measure distances to the closest combustible materials (like the mantle) and take action if needed.


The Type of Chimney

There are 2 types of chimney found on residential properties. These are:

  • Type 1 chimney - a traditional chimney found on older properties that is usually made of brick or stone. A type 1 chimney was mainly designed for an open fireplace and will have an internal diameter of at least 7 inches. On older properties a type 1 chimney may require a flue liner as the chimney might not be sealed anymore.
brick chimney

Type 1 Chimney


  • Type 2 chimney - a type 2 chimney is a prefabricated flue. It is made of pieces of metal flue pipe joined together. Prefab flues are built for gas, electric, and gel fires. They can't handle a solid wood fire of the kind used in a wood burning stove.
metal chimney

Type 2 Chimney

In summary, you can only install a wood stove in your fireplace if it is served by a type 1 chimney.

This is likely to be the case if the fireplace burned a solid wood fire before.

If you're replacing a gas fireplace then your type 2 chimney isn't suitable for a wood stove replacement.

Actions:

  1. Check that you have a type 1 chimney.
  2. Check for air gaps in older chimneys. Cracks need to be repaired too. It's best to consult a professional to ensure your chimney is up to standard.


Size and Diameter of the Flue

The next essential check to make before you go ahead and purchase a wood stove for your fireplace is that the flue will fit comfortably.

We've checked that the chimney is the right type to accommodate a wood stove fire but we also need to ensure that the intended flue won't be restricted in any way.

Large wood stoves will generally need a 7 inch flue pipe. Smaller stoves might need just 5 inch flue diameters.

This is something that your wood stove dealer can confirm for you. This information should also be prominent in any manual or in the product specifications

Actions:

  1. Ensure the stove flue can fit comfortably inside the existing chimney.


Problems to Avoid

The flue size needs to be closely matched to the heat output of the stove or the gases inside may be cooled by the large surface area of the excessively large flue.

Excessive cooling of the exhaust gases can cause:

  1. Condensation build-up
  2. Creosote build-up
  3. Low flue gas velocity

These are potentially dangerous problems (and at the least, expensive problems) that you shouldn't be dealing with if a wood stove is installed in a fireplace correctly.

It's best to consult a professional if you're unsure about any aspect of the installation.



Ventilation of the Room

Proper ventilation is really important if you want a safe and efficient heating operation in your home.

Air is essential to combustion and a steady flow or light breeze circulating through your room will ensure that there are no problems like smoke not escaping up the chimney properly.

The air intake should ideally be as close to the stove as possible and should always remain free of obstruction. The point is to provide fresh air circulation to the stove.

The cross section of the ventilation should be equal to at least one quarter of the cross section of the flue pipe so it doesn't need to be huge.

The minimum size of ventilation is around 0.15 square feet and it basically works out at about 0.15 square feet of ventilation for every 1 kW of wood stove heat output.

That's roughly 0.15 square feet of ventilation area for every 3,400 BTU of heat output.

An air vent is usually installed as part of the wood stove kit (an added extra) or it can be installed as a brick with an air pipe through it.

Don't worry, proper air ventilation won't defeat the purpose of your stove and make the room cold!

Actions:

  1. Plan for proper ventilation.
Wood Stove Fire Burning

Size of the Wood Burning Stove

By this point you should know about clearances and flue sizes. If not, we encourage you to read the last few sections.

The next key point to remember is that the size of your fireplace should not dictate the size of the wood stove that you're installing in it.

The size of your room should.

If you get a stove that's too large or too small then you will have difficulties heating your home efficiently.

You might have needed a large fire burning in your fireplace before to heat up your room but wood stoves are a much more efficient beast!

It's tempting to fill a large fireplace with a large stove but it might not be necessary. 

Essential Tip: The heat output of a wood stove needs to closely match the size of the room it heats.

Actions:

  1. Match the wood stove to the size of your room and don't be tempted to fill your fireplace with a large stove purely for aesthetic reasons.


Check Local Regulations

Make sure there are no local planning laws that you may fall foul with. Check-in with the local state planners just to be on the safe side.

In certain jurisdictions, there are legal requirements that you must comply with regarding wood smoke emissions.

In some communities, there are restrictions on the installation of wood stoves in any newly constructed building, although the most common action is limiting the use of wood stoves whenever there is a threat to the area’s air quality.

There are ever changing emission guidelines now that dictate how much PM (Particulate Matter) a wood fuel burner emits. 

Make sure your installation and your chosen stove are up to scratch with the EPA in 2022.

Actions:

  1. Check any local planning regulations.
  2. Check wood stove emission guidelines.
wood stove in a fireplace


How to Install a Wood Stove in an Existing Fireplace

Although installing a freestanding wood stove in a fireplace may sound like a lot of hassle, it isn’t necessarily as complicated as it might seem.

In fact, a wood-burning stove represents an excellent alternative when compared to a regular open fireplace since wood stoves are designed for burning wood more cleanly and efficiently than a traditional fireplace.

Having an enclosed combustion chamber provides huge benefits when it comes to fuel efficiency, heat output, and also in exposing of harmful exhaust emissions.

As long as there’s enough space in your existing fireplace for your chosen wood burning stove and as long as there is a useable chimney for venting, you can easily install a wood stove in an existing fireplace.

Here's how it's done.


Quick Recap

In the last section, we covered the pre-checks that need to be made to ensure your fireplace is compatible for a wood stove installation.

In summary, you need to do the following before you think about buying a stove:

  1. Does your hearth meet requirements?
  2. Is there sufficient clearance to combustible materials?
  3. Is your chimney suitable for a flue pipe?
  4. Can you run a big enough flue for the wood stove in question?
  5. Have you planned for ventilation?
  6. Do you know what size (heat output) of wood stove is needs for your room?
  7. Have you researched local regulations for wood burners?

We cover these points in detail in the first section.


Recommended: Don't miss our wood stove safety tips.


Wood Stove Installation Process

Your home meets the requirements to have a wood burning stove installed in your fireplace, so what next?

We'd always advocate hiring a professional to install a wood stove in an existing fireplace.

They know the local laws and will ensure a clean and efficient installation.

But, if you're curious or keen to try for yourself then these are the next steps when it comes to the actual installation.


1. Choosing a Suitable Wood Stove

Like we mentioned earlier, the heat output of the wood stove should be closely matched to the size of the room it will heat.

Don't worry these numbers are always prioritized by sellers and easily available when shopping for wood stoves.

Stoves will be categorized by heating output (BTU) or by the size of room they can heat in square feet.

You also need to have your installation option firmly in mind at this stage.

Will the wood stove sit inside the fireplace and be vented by a flue going from the top of the stove directly up?

Or will the stove sit forward from the fireplace opening with the flue pipe extending from the back of the stove?

The two images below show how the flue can exit a stove.

stove installation in chimney
installing a wood stove flue in a fireplace

So be sure that any stove you consider purchasing can be vented in the way it needs to be.


2. Prepare the Chimney

Regardless of which type of flue installation you are going ahead with, your chimney should be inspected for cracks and gaps. Any past creosote build-up should also be removed at this stage.

You can find a certified chimney specialist here.

The flue or flue lining needs to be prepared at this stage too. A professional should help with this.


3. Prepare the Flue

There are a few flue installation options available when installing a wood burning stove in an existing fireplace.

Essentially, we need to run a flue up the chimney so that only the exhaust gases are funnelled out.

It's critical that the flue is sealed properly too.

These are the installation options available to us:

Option A

Wood stove installed in fireplace

The preferred option for those with a large enough fireplace opening is to position the wood stove inside and run the flue directly upwards.

Here you can:

  1. Run the flue all the way up the length of the chimney.
  2. Run it past the damper (which is held open or removed).

Both options require the chimney to be sealed around the flue.

If choosing option two you'll need to line your chimney. 

These stainless steel liners help with the draw of the stove and prevent low flue gas velocity.

You'll need to get the right diameter and length of liner and hire a professional to install them. They'll be connected to new chimney caps at the top of the chimney.

The flue is then run directly upwards from the wood stove and capped with a register plate at the throat of the chimney. This ensures the only airflow entering the chimney is through the stove.

A non-flammable material needs to fit tightly around the flue and hold the register plate firmly in place.

This needs to be able to deal with extreme heat and also remain strong enough to stay in place if anything might fall down the chimney.

This is the ideal type of installation as a straight flue removes combustion gases much more efficiently than one with bends in it.

It's also the more space efficient installation as we don't use up any floor space.


Option B

The stove is positioned on an extended hearth. The flue usually extends from the back in this instance but can also extend from the top of the stove like before.

stove installation in chimney

Here, the chimney opening is sealed with a heatproof shield. The flue fits in a new opening made above a closed damper.

It's essential that any airflow is sealed at the damper. We can do this with sheet metal and rock wool.

installing a wood stove flue in a fireplace

We can also vent from the back of the stove on an extended hearth.

About the Author Jamie

I'm an English teacher and writer. I'm passionate about the environment and love the tiny house movement!

Share your thoughts

Your email address will not be published. Required fields are marked

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}