This option is for a house with no chimney, but the flue cannot go up through to the roof for various reasons, then a false chimney breast is built, the stovebox is inserted and the twinwall goes up only to the first metre above the top of the box and then at an angle out through to the exterior up to the recommended height.
Obviously when building a false chimney breast, consideration needs to be taken:
There 2 main reasons to build a breast eg:
Specialist advice will need to be taken when choosing products such as a gas stoves. This will need a gas twinwall and should be advised by an installer that is gas safe . A wood or multifuel stove are covered by an Hetas installer.