Non-chimney installs

Twin Wall Flue Installations


If you do not have an existing chimney in your home and you want to install a wood burning stove, or if you want to install a free standing modern wood burning stove, you will need to use Twin Wall, Insulated Flue Pipe. We have a complete range of Double Wall Flue pipe from Convessa and Dinak DW a high quality brand of stove pipe.


No Two Twin Wall Flue Installations are the same


Because no two installations of twin wall flue pipe are exactly the same we cannot supply kits, as we can with the flexible flue liner kits. You have to decide where you want the flue to run through the house. You need to either go through a wall and then out and all the way up an external wall to above your roof or you need to go up internally, through your floors and through the roof itself. The path the flue will take to do this will depend upon the configuration of your home and how you want to route the flue pipe.


Accordingly you will have to plan and measure out your twin wall flue system. If you do not feel comfortable doing this then you can get in touch with a local builder or HETAS installer, who will be able to help you. Either way you should make yourself familiar with the building regulations as wood burning stoves do fall under these regulations - more information can be found here. This page is designed to help you understand how to put your system together and take some of the mystery out of planning an installation and not be a complete guide.


1) How to start your insulated flue system


You should start your system with a length of single wall vitreous enamelled pipe as this is both cheaper and harder wearing, so is more suitable for use with the high temperatures experienced directly from the stove.  You can however, for asthetic purposes etc, you can begin your run by using the adaptor to twill wall and cementing this directly into your stoves flue collar.

If you start your run with single wall pipe you can run internally with this but you cannot pass through walls, ceilings or roofs with it and it can only be used internally. If you have a larger internal wall to scale before going through any obstacles then by all mean use the Enameled Stove Pipe all the way up internally, as this is more economical. You must just convert to twin wall pipe at least 4 inches before passing through a wall, ceiling or roof.

2) Converting from Single Wall Stove Pipe to Twin Walled Flue Pipe


Before passing through a wall, ceiling or roof, you will need to convert to twin wall flue pipe using a Converter from Single Wall Adaptor, found here. This slides into the top of your single walled pipe and allows twin walled flue pipe to be attached to the other end. This plus all other joins between pipes in a twin wall flue system require a locking band to seal the join, which is included free with our Convessa range of pipe but must be purchased seperately in the Dinak range. Alternatively some of our wall brackets include a locking back, so you can strategically place your wall mounts at the joins of the pipe to save on components.

3) Building your Insulated Flue Pipe System

Now you have converted to Double Walled Flue Pipe you just have to plan your route and measure out what components, pipe lengths and bends you will need.

4) Passing your twin wall flue pipe through a wall

If you decide to go through a wall, you will need a wall sleeve to protect the wall and a finishing plate to cover the hole, which must be larger than the outer diametre of the pipe to avoid it touching the wall. These two components allow you twin wall pipe to safely pass through a wall. Once outside you can just attach a 45 degree elbow and continue directly up the external wall.

5) Passing your double wall pipe through a ceiling

If you decide to continue internally, then you can pass through a ceiling using a firestop plate, which ensures that you cut back the ceiling far enough away from the pipe and covers and finishes the holes. Please note: you must use a ventillated firestop plate for wood burning stove installations, the plain firestop plates are for gas installations only.  You need to use one either side of your floor (i.e. one on the ceiling and one on the floor above).

6) Passing your insulated pipe through a roof

To pass throguh a roof again be sure that no part of the roof touches the pipe. Use a firestop plate on the underside of the roof to cover the hole and flashing on the top of the roof to seal it. You will need the high temperature flashing if your insulated pipe passes through the roof less then 5 meters away from your stove, otherwise the low temperature flashing should be fine. If you have a corrigated or uneven roof you will need the EPDM masterflash which moulds to the shape of your roof. A fixing kit is available for the flashing which gives you everything you need to create a weather proof seal.

You will need a storm collar to clamp the top of the flashing tight round the twin wall flue pipe to create a weather proof seal.

7) Insulated flue pipe chimney cowls

You need to ensure that your twin wall flue pipe is at least 600mm higher than the pitch of your roof or the top of your flue pipe should be at least 2.3m horizontally away from the roof as it slopes away, whichever comes first.  On top of your pipe you will want to finish off with a chimney cowl or rain cap, available here.