Balanced Flues and Conventional Flues Explained

Making the Right Choice for Your Stove or Fire

Flues play a crucial role in venting combusted gases from stoves and fires, making it essential to choose the correct type of flue for your needs. In this article, we will explore the differences between balanced flues and conventional flues while also considering flueless products.

Existing Setup and Considerations

When selecting a flue type, you have two main factors to consider: the existing setup and the fuel type you plan to burn. The main distinction between balanced flues and conventional flues lies in their design and functionality.
wanders danta 1100 gas fire 1
Wanders Danta Gas Fire

Conventional Flues:

Conventional flues are the standard chimneys found in most UK homes. If you have a traditional brick chimney, it is likely a conventional flue. These flues work by allowing air to pass over the top of the chimney, drawing warm air out of the chimney while pulling air from the room through the stove or fire and up into the chimney. As a result, conventional flues need to extend high above the roof line and should terminate in clear air, at least 2.4 meters away from any obstruction or 600mm above the roof ridge.


There are different types of conventional flues, such as Class 1, which are brick-built or clay/concrete lined traditional chimneys that open out into a fireplace. On the other hand, Class 2 chimneys are prefabricated metal flue systems that connect directly to a stove/fire without the need for a fireplace.


All wood-burning, multifuel, and pellet stoves/fires require conventional flues to function properly. Gas stoves and fires can work with multiple flue types, but they are usually designed for either conventional or balanced flues, so it’s important to choose the right version for your home. Depending on the property’s age and the appliance being used, conventional chimneys may require lining.

yeoman cl8 conventional flue gas stove
Yeoman Conventional Flue Gas Stove
yeoman cl8 balanced flue gas stove
Yeoman CL8 Blacned Flue Gas Stove

Balanced Flues:

Balanced flues are applicable only to gas stoves and fires. They consist of two pipes, one inside the other. The inner pipe removes waste gases, while the outer pipe brings in the air required for combustion. These flues, also known as concentric flues, should not be confused with twin-wall flues. Balanced flue appliances are considered “room sealed” because they draw all combustion air from outside and do not require additional air from the room. Consequently, all balanced flue stoves and fires have a glass front or closed door that cannot be opened.


Since hot and cold gases exchange within the same pipe, the outside of balanced flues remains cooler than conventional flues. This feature allows balanced flues to terminate at a lower level, with the only requirement being an external wall where the flue can be directed out the back of the appliance, through the wall, and terminated.


There are specific regulations regarding termination locations, distances, and the amount of free air circulation around the pipe, which may vary between appliances. However, as a general rule, if you have at least 1 meter of free air space around the termination point and it is not directly below a window, you should be compliant (check the appliance’s specifications for further clarification).

Converting Conventional Flues into Balanced Flues:

A common question we receive is whether it is possible to convert a conventional flue chimney into a balanced flue to accommodate a built-in balanced flue fire or freestanding stove. The answer is yes, it is possible, but only with certain products, therefore before making a purchase, ensure that the appliance you are interested in is compatible with these renovation kits.

Wanders Lenga 500 ABE

Chimney Renovation Kits offer a solution to convert conventional flues into balanced flues. These kits provide a concentric pipe off the top of the balanced flue stove/fire into the chimney, where they seal into a special register plate. The inner pipe connects to a chimney liner that runs all the way up the chimney and connects to a special cowl, safely venting the waste gas. This cowl also has lower vents that allow clean air to pass through the void between the outer brick/concrete material of the chimney and the inner liner. The fresh air is drawn into the appliance through the vents at the bottom of the chimney in the special register plate, effectively using the conventional flue as a balanced flue.

wanders tali xl white
Wanders Tali XL Balanced Flue Gas Stove
wanders tali side glass black
Wanders Tali 3S Balanced Flue Gas Stove

Flueless Products:

An alternative to conventional and balanced flue stoves or fires is to choose flueless models. Flueless products, including electric, bio-ethanol, and gas options, do not require flues or chimneys to operate. Gas stoves and fires equipped with a catalytic converter burn off waste gases, emitting no fumes back into the room and thus requiring no flue. However, the output of flueless products tends to be lower, typically less than 4kW, making them more suitable for decorative purposes or smaller rooms.


Bio-ethanol fires are another flueless option that releases only water vapor into the room. It is crucial to note that all flueless gas and bio-ethanol products require a minimum amount of air exchange within the room they are placed and can often result in additional room vents. There are also minimum room size requirements on many larger bio-ethanol fireplaces, so check that your room is suitable for a flueless product before making a purchase.

Which is Right for Your Home?

Choosing between balanced flues and conventional flues depends on your existing setup and the type of stove or fire you plan to use. If you have no chimney or want to place a fire in a location without a chimney, a balanced flue is an excellent option. For converting conventional flues into balanced flues, chimney renovation kits offer a solution but are limited to certain products.


Flueless products provide a chimney-free alternative, but output limitations and room size requirements should be taken into account. Whatever your choice, understanding the differences between these flue types will help you make an informed decision for your home. If you have any questions or need further assistance, please feel free to reach out in the comments below.

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