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Flexible Liners

We pride ourselves in giving a first class service using good quality materials. It is so important to install good quality flexible flue. The ability for the flue pipe to bend and withstand the forces that are generated during the installation and annual cleaning process is clear. A chimney sweeps brush will exerts pressure on the pipe to ensure that it actually cleans the sides of the flue, bends in the pipe increase these loads further. All flexible flue is made as in one big spiral, the joints of the spiral are the week points, a cheap flue may have weaker.

Gwent fire installations carry out the following work as standard on a all flexible flue fittings.

• Installing a fully clamped and supported liner mounted on a steel plate underneath the chimney pot.

• Maintaining the Existing chimney pot where possible to ensure the look of the house is unaltered, usually with the addition of a Terracotta rain cap if required.

• A steel register plate is installed to isolate the chimney cavity from the room, this ensures that even heavy masonry falling from the flue will not enter the room. This makes for an extremely safe installation.

• The rigid fixing of every flue joint ensures that a seal is maintained and eliminates the risk of separation when cleaning.

Insulated Flue Pipe

Generally Insulated flue is used where a normal chimney does not exist Insulated flue pipe is otherwise known as twin wall insulated flue pipe. This product could be supplied by a number of manufacturers.

Firstly the insulating materials itself must be of a 'packed or compressed' type. This means that there is very little chance of the insulating material compressing or going to the bottom of the tube. If this does happen then the pipe is no longer insulated and 'hot spots' are formed increasing the risk of fire.

Rigidity of an assembly is important as this quite often forms a complete chimney on the outside wall of a house it must be able to withstand all weathers, including winds.

Stove J Building Regulations The 2002 edition of Approved Document J of The Building Regulations stipulates that any work that affects an existing chimney now comes under building control. This means any modifications or additions i.e. Fitting a stove (even replacing an old one), lining a chimney or modifying the existing design of a flue

An existing chimney or a new flue or chimney installation must be given a visual inspection to check that it is in good order (this should take the form of a risk analysis based on the safety of the installation). It must be clear of obstructions and be of a suitable size and type for the appliance you plan to install. It may be necessary to sweep the flue (which should always be done prior to fitting a stove or lining a chimney) and also, if necessary, to do a smoke test to check for gas tightness.

A checklist should be completed showing that "the materials and components appropriate to the intended application have been used and that flues have passed the appropriate tests"

A permanent notice plate should be fixed at an appropriate position giving details of the location of the fireplace, the type and size of the flue and type of heating appliance used.

Other Building Regulations that commonly affect stove and flue installation

Flue pipe clearance when adjacent to combustible materials

Any single wall flue pipe used, both rigid and flexible, must not be closer than three times the diameter when adjacent to combustible materials (i.e. wooden fireplace lintel). 

Flue height above the roof

To calculate the minimum height of a flue above the roof line, it is best to refer to the images given in the relevant approved document or ask Gwent Fire Installations about your specific requirements. However it can be said that as a minimum length you must have a flue at least 4.5m high for a closed appliance/stove and 5.5m for an open fire.

Ventilation

Fixed ventilation must be provided when installing any solid fuel stove which has an output higher than 5kws. Therefore 550 sq mm/Kw over 5Kw of ventilation is required. This means fitting an airbrick of sufficient size.

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