Twinwall Flue Pipe

So what do you do if you want a wood or multifuel stove but you don't have a conventional chimney? The answer is to use a twinwall flue system. We get a huge number of calls asking questions about twinwall flues, so I decided to write this post covering the basics of twinwall.

What is Twinwall Flue?

Twinwall flue consists of sections of double-skinned stainless steel pipe, with a thick layer of insulation between the inner and outer skins. Twinwall pipe is available in a wide range of straight and angled pieces, and you can also get terminals, adapters, support brackets, etc to suit your twinwall flue. A twinwall flue system is made up of whatever combination of straight and angled components is the best fit to the installation location.

Where Can I Use a Twinwall Flue System?

Twinwall flue can be used for both internal and external flue systems. A typical internal system would go straight up from the top of the wood or multifuel stove, going through any ceilings and out through the roof. A typical external system would go out through an external wall then run up the side of the building to roof level.

What Can't I do With a Twinwall Flue System?

The number of turns and offsets in the flue system should be kept to a minimum to ensure the flue gases can flow smoothly. The internal bore of the twinwall pipe should never be smaller than the flue outlet of the multifuel / wood stove - in fact many manufacturers recommend an increase in diameter for the flue system. Also there some limits to how close the flue system can be placed to windows and regulations about the height at which the flue terminates.

How Does Twinwall Flue Connect to a Multifuel / Wood Stove?

Twinwall flue can be connected directly to the flue outlet of the wood or multifuel stove using an appliance adapter. Alternately an initial short run of standard single-wall stove pipe can be used before connecting to the twinwall pipe using a single-twinwall adapter.

Will Twinwall Flue Look Right in my Home?

Twinwall flue comes in a stainless steel finish as standard, and people are sometimes concerned that this will look too obtrusive, especially if they are using it in a period interior or with a traditional multifuel or wood stove. Some twinwall manufacturers can supply powder-coated pipes for an extra charge to give a more understated look.

Can I Add to an Existing Twinwall Flue System?

Twinwall pipes fit together very precisely, then the joint is sealed using locking bands. Each twinwall manufacturer uses their own locking system, so it is difficult to connect twinwall pipes made by different companies due to the connections being incompatible. While it is possible to get an adapter custom-made to connect two different brands of twinwall, this is expensive and you would have to first identify the brand of the existing flue system.

Stores Direct are a leading UK supplier of multifuel / wood stoves and flue systems, with nationwide delivery available. We also offer a free twinwall flue design service - to take advantage please provide a simple diagram with measurements (fax to 01484 773170 or email to showing where you want to site the stove and flue. One of our HETAS qualified technical advisors will then design and calculate the price of your flue system. Flue designs are usually completed within 24 hours, although a peak periods it may take a little longer.