In a situation where there is no existing chimney, a double skin insulated flue pipe allows you to easily build a new. You can also build anew chimney using a pumice liner system. Double skin insulated flue pipe creates a Class I insulated chimney.
The insulation means that the flue gases stay hot as they rise thus reducing tar condensation. This reduces the risk of chimney fire. Even in double skin flue a chimney fire would still ruin the flue pipe and is still very dangerous. Double skin flue pipe has a larger diameter than single skin flue pipe because of the insulation. Our double skin flue pipe has an external diameter 50mm (2 inches) wider than the internal diameter.
This means that if you use a length of single skin stove flue pipe first that there will be a visible changeover from the narrower single skin flue to the wider double skin flue. It may be that this changeover can occur close to the ceiling (150mm is the minimum distance) and will not be a problem.
In a situation where the room is taller and the changeover would be very visible it looks better to run the entire length in double skin flue pipe.
The flue must be supported every 2m and must have at least one supporting component. A supporting component takes the weight of the flue system. Supporting components are floor support plate, rafter support bracket, and wall support bracket. The floor support and rafter support are our preferred supporting components for internal installations (they look better and are easier to use), whilst a wall support bracket is used for external installations.
The flue may run within 50mm of combustible materials and can come with components that make boxing it in easy. There is a recommendation that double skin flue should be boxed in where it passes through a storage area, ie within cupboards or loft spaces, to prevent stuff being accidentally leant against it. The double skin insulated flue pipe can safely pass through existing floors and through the roof.