With this type of installation, consideration needs to be given to the minimum separation distances a connecting flue pipe can be installed to combustible material. This can be achieved in one of the following ways:
- by ensuring the separation distance between the flue pipe and the combustible material is a minimum of 3 times the diameter of the flue pipe; or
- by ensuring the flue pipe is a minimum separation distance of 1.5 times its diameter to combustible material and that a non-combustible heat shield (metallic construction) is installed which extends a minimum 1.5 times the diameter of the flue pipe (1 times diameter in the Republic of Ireland). The heat shield should be affixed using non-combustible fixings and spacers, leaving a minimum air gap of at least 12mm (12.5mm in the Republic of Ireland) between the heat shield and the combustible material. The shield should not be affixed directly to combustible material as the fixings could conduct heat, leading to charring and eventual ignition of the combustible material.
Measurements except for the Republic of Ireland
Measurements for Republic of Ireland only
Alternatively, a twin wall system chimney could be used as the connecting fluepipe (check regional regulations on minimal designation), which will reduce the transmission of heat to combustible material, with the minimum distance denoted as ‘xx’ to combustible material as declared by the manufacturer.
Appliance manufacturers instructions also need to be adhered to ensure combustible material is located at the distance they specify to protect it from radiated heat.
Image credit: iStock with OFTEC diagrams
This article originally appeared in the 2024 autumn issue of Oil Installer magazine. View the magazine