Flue Pipes
Regulations
The flue pipe must be installed to comply with Document J of the Building Regulations in England and Wales and part F of the Building Regulations in Scotland.
Flue Design
The vitreous enamel and Prima Plus 1mm are used as connecting flue pipes from the appliance to the chimney and must only be used in the room where the appliance is installed. The maximum length for the vitreous enamel is 1.8 metres as recommended by the manufacturer. The Prima Plus 1mm may also be used to reline existing masonry chimneys and is approved for this use by HETAS.
It is a recommendation that a vertical rise of 600mm should be allowed, immediately above the appliance before any change of direction.
Use of an adjustable length within the flue pipe connection immediately above the appliance enables removal of the appliance later without dismantling the full system.
If bends are needed, then no part of a flue pipe should form an angle greater than 45° from the vertical, except where it may be necessary to use a very short horizontal section, not exceeding 150mm, of flue to connect the flue pipe to a back outlet appliance. A maximum of four bends (2 offsets) is permitted.
Distances from combustible materials must be three times the diameter of the flue pipe eg.150mm od = 450mm clearance unless otherwise specified by the flue manufacturer.
Flue Size
The size of the flue pipe should be as recommended by the appliance manufacturer and in most cases should not be smaller than the appliance outlet. Confirmation from the appliance manufacturer will be required if you intend to reduce the flue pipe size.