Installing a Twin Wall Flue Pipe in a Campervan
Installing the flue system is one of the most important parts of fitting a stove in a campervan. The flue is responsible for safely carrying smoke and gases from the stove out through the roof of the van.
In most campervan installations this involves using single wall flue pipe inside the van and twin wall insulated pipe where the flue passes through the roof.
Twin wall pipe helps protect surrounding materials from heat and improves airflow through the chimney, helping the stove burn efficiently.
Below we explain how the typical system fits together.
Understanding the flue system
A campervan stove flue is usually made up of several components working together.
Starting from the stove, the system normally includes:
• The stove spigot
• Single wall flue pipe inside the van
• A single wall to twin wall adapter
• Twin wall insulated flue pipe through the roof
• A roof flashing or silicone boot
• A storm collar
• A rain cap
Each component plays a role in making sure the flue operates safely and efficiently.
Single wall pipe inside the van
The first section of pipe connected to the stove is usually single wall flue pipe.
Single wall pipe becomes hot when the stove is running, which helps improve the natural chimney draw. This strong airflow helps smoke travel up the flue and out of the van.
This section of pipe connects directly to the stove spigot and runs vertically upward inside the campervan.
The single wall to twin wall adapter
Before the flue passes through the roof, the system transitions to twin wall insulated pipe.
This is done using a single wall to twin wall adapter.
The adapter connects the internal single wall pipe to the insulated twin wall pipe above. This change in pipe type is important because the roof area requires additional heat protection.
Twin wall pipe through the roof
Twin wall flue pipe contains insulation between two layers of steel.
This insulation helps:
• keep flue gases hot
• improve chimney draw
• reduce the distance to combustible materials
• protect the roof structure from excessive heat
Twin wall pipe is typically used from the ceiling level upwards through the roof of the van.
Passing through the roof
Where the flue passes through the roof, a silicone boot or flashing is installed.
The boot sits on top of the van roof and forms a waterproof seal around the pipe. It is normally fixed using self-drilling screws and sealed with silicone adhesive.
Inside the van, an internal cover plate is fitted to create a neat finish where the flue passes through the ceiling.
This also helps secure the system in place.
Storm collar and rain cap
Once the pipe is above the roof, the final components are fitted.
A storm collar sits around the pipe above the roof flashing. This helps prevent rainwater running down the pipe and entering the roof seal.
On top of the flue, a rain cap is fitted. The cap prevents rain from entering the chimney while still allowing smoke to escape freely.
Keeping the flue straight
Where possible, the flue should run straight up through the roof.
A straight chimney creates the best airflow and helps the stove burn more efficiently. Bends and angles can reduce the strength of the chimney draw.
This is why the stove position is often chosen so the flue can run vertically.
Planning before cutting the roof
Before cutting the roof hole, it’s always worth positioning the stove and assembling the flue temporarily.
This allows you to check:
• the flue alignment
• roof position
• clearances around the pipe
Taking time to plan this stage carefully can make the installation much easier.
A simple and reliable system
Although it might look complicated at first, the flue system is actually quite straightforward once you understand how the components fit together.
A correctly installed twin wall flue system allows the stove to operate safely while keeping the installation neat and secure.
How Do You Know Where to Drill the Roof Hole?
We have an article that explains this in depth!
One of the most common questions when installing a stove is how to know exactly where to cut the hole in the roof.
A simple and reliable method is to use a piece of string and a small weight, such as a nut or bolt.
Start by placing the stove in its final position and fitting the internal flue pipe so it runs vertically upwards. Tie a small nut onto a piece of string and hold it at the centre of the flue pipe opening.
If the van is level, the weight will hang straight down like a plumb line. This shows you the exact centre point of where the flue will pass through the roof.
Mark this point carefully before cutting.
Many van builders use a hole saw to cut the opening, but a jigsaw with a metal blade can also work well on metal roofs. Some people also use metal nibblers.
Taking time to mark the hole correctly before cutting helps ensure the flue passes cleanly through the roof and lines up perfectly with the stove below.
Need help installing your flue?
If you have questions about installing a stove or flue system in your campervan, feel free to get in touch.
We’re always happy to help and talk through different installation setups.