Can You Install a Stove in an Existing Fireplace?

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Do you have a traditional fireplace in your home but are starting to see the positives of buying a wood burning stove? If so, you might be wondering if it’s possible to install one into your existing fireplace.

The good news is that installing a wood burning stove into an existing fireplace is often a straightforward job. You just need to ensure you have the correct:

  • Chimney type
  • Flue diameter
  • Fireplace opening size
  • Stove heat output
  • Room ventilation
  • Hearth size and thickness

Read on to find out more about how to fit a wood burner in your fireplace!

What to Know Before Installing a Wood Burning Stove in an Existing Fireplace…

Whether you are opening a fireplace especially for a wood burner, or have an empty recess ready to go, consider these things when installing your stove…

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Chimney and Flue Size

You can only fit a wood burner in your fireplace if it has a class 1 chimney. If you had an open solid fuel fire previously, this should be the case anyway! If you are replacing a gas fire, check to make sure it isn’t a class 2 or pre-cast flue, as these won’t be suitable for a stove.

Next, you want to check the diameter of your fireplace flue. It is very important that your wood burner is connected to the correct size flue or flue liner – if it isn’t, it will not only perform badly, but won’t be safe either.

Most stoves of up to 20kW need a minimum of a 6” flue diameter. If you have a DEFRA approved stove and your manufacturer says it is safe to do so, a 5” flue can also sometimes be used.

You can find out more about what flue you need for your stove here.

If your fireplace chimney is smaller than the required flue diameter for your stove, it won’t be safe to install one. You will have to watch out for any cracks, too – even if you are installing a flue liner, they will have to be repaired.

For chimneys that aren’t suitable for use with a stove for any reason, you do have an alternative by installing a twin wall flue. See how they can help you have a stove without an existing chimney here.


  • You must have a class 1 chimney
  • Be sure to check the diameter of the flue in your existing fireplace before you buy your stove

Distance to Combustibles

If you are fitting your stove into an existing fireplace chamber, you need to make sure it is big enough to allow for the required distance to combustibles – this means it must be the stated distance away from anything like plasterboard or wallpaper that has the potential to catch fire. The specific required distance is different for every stove, so check the installation manual before fitting yours.

If the fireplace is made of only brick, stone or other non-combustible material, there is no legal regulation on how far away the stove needs to be. However, performance of the stove might be affected if there isn’t enough space to allow air and heat to circulate.

If you have messy brickwork in your fireplace, you can easily neaten it up for your stove with one of our fireplace chambers.

Rustic Brick Fireplace Chamber

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  • Measure your fireplace chamber to see how well your stove will fit inside it
  • Ensure there are no combustible materials within the required space around the wood burner

Stove Heat Output

Stoves are significantly more efficient than fireplaces and can give out a lot of heat!

Even if you have a big fireplace opening for your wood burner, that doesn’t mean you should fill with as large a stove size as possible.

Use our stove calculator to work out what heat output is best for your room to avoid it getting too hot.


  • Make sure you are choosing the correct heat output when putting a stove in a fireplace


Stoves need air to be able to work. When they are placed in a room without enough ventilation, you can experience all kinds of issues, such as smoke failing to rise out of your chimney and difficulty getting your fire started.

If you are putting a wood burner in a traditional fireplace, make sure you check the air permeability of the room. If it is too low, you might need to fit a small ventilation brick somewhere.

You can find out more about log burner ventilation here.


  • Check that your room has adequate ventilation to place a stove in your fireplace


Stove Hearth and Surround

When putting a wood burner in a traditional fireplace, you need to follow the correct regulations when it comes to the hearth you use. As your stove will likely be a different shape and size to a traditional fire, don’t assume that it will still be suitable.

Stove installation regulations require that hearths that reach up to 100°C should:

  • Extend at least 300mm to the front and 150mm to both sides of the stove
  • Have an area of at least 840 x 840mm
  • Be at least 12mm thick
  • Be made from non-combustible materials

If the hearth temperature exceeds 100°C, it should be a minimum of 250mm in thickness.

For very old fireplace openings, make sure there are no cracks in the hearth if you plan on reusing it – stoves throw out a high level of heat, and cracks can quickly become an issue.

We have more information about stove installation regulations here.

You might also have an old fireplace surround you want to keep for your wood burning stove. If your fireplace opening is big enough and it is made from a non-combustible material, there is no reason why you have to replace it. However, a fireplace beam is often preferred.

Gallery 54 inch Dark Oak Geocast Beam

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  • Measure the hearth of your fireplace to make sure it is the correct size for a stove
  • If the hearth is too small, damaged or not a suitable material, replace it with a new one

Can You Open Up an Old Fireplace For a Wood Burner?

If you have a completely boarded up fireplace, or maybe a gas fire in a recess, it is possible to open it up to fit a stove inside. However, again, this will depend on a few things.

First of all, it’s important that the fireplace opening size is big enough to accommodate a wood burner. Unfortunately, you might know exactly how big the builders opening to your fireplace is until you get to work knocking it through!

The exact fireplace opening size you need for your wood burner depends on what size stove you want. You need to be able to leave enough space around the stove to provide the required distance to combustibles and to ensure an adequate air supply is available to the stove.

If your fireplace opening is on the small side, don’t worry – take a look at our range of small stoves to find something that will fit in nicely!

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Remember, if your fireplace has been boarded up for some time, you will also need to check that the chimney is in a good working order. You will need to ask a chimney sweep to clean it and inspect it to make sure there are no cracks. If there is no chimney liner, consider installing one to make your stove as efficient and safe as possible.

Find out more about why your stove needs a flue liner here.

Are you looking for a wood burner to fit into your fireplace? Take a look at our fantastic range online at Direct Stoves – all with free delivery and finance options available.

You can find more stove installation advice and buying guides on the Direct Stoves blog

Can I Install a Wood Burning Stove in a Conservatory? | What Do You Need to Fit a Log Burner? | Log Burner Fireplace & Surround Ideas

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