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Chimney Liner installation best practices

Ultraflex Information

Follow these essential best practices when installing your chimney liner and appliance.

  • Ensure that when fitting an appliance to an existing chimney system, it is inspected and tested for soundness. Any defects found should be rectified promptly.
  • Always install and support the chimney or flue system securely, ensuring that all joints are made properly and efficiently following the manufacturer's instructions.
  • Ensure the flue pipe connection from the appliance rises vertically for a minimum of 600 mm before considering any change in direction. This vertical rise is crucial due to the higher flue gas temperature near the appliance. Avoid horizontal or angled runs at the bottom of the flue to prevent restrictions to flue gas movement.
  • Construct the chimney vertically up to the terminal whenever possible. If bends are necessary, limit the number of bends to a maximum of four. The maximum bend angle should generally be 45° from the vertical, except for 90° factory-made bends or tees, which can be considered as two 45° bends.
  • Make sure the chimney flue diameter is not smaller than the appliance outlet diameter. The effective height of a chimney with bends should be at least twice the horizontal distance between the appliance and terminal.
  • Position the chimney inside the building to prevent excessive cooling and condensation risks. Install and locate the chimney following Building Regulations and British Standards, especially regarding distances from combustible materials.
  • Thoroughly inspect the chimney and conduct smoke tests before using the appliance. Ensure a permanent supply of combustion air is provided and kept clear from obstructions.
  • Regularly check heating appliances and have the flues expertly swept. Ensure the installation is done by a HETAS registered installer and install an approved Carbon Monoxide Alarm.
  • Correctly complete and position the Notice / Data Plate for each installation.
  • Don't use a single wall flue system as a chimney.
  • Don't  allow clothes, furnishings, or any combustible materials to come into contact with the surface of any flue pipe or prefabricated metal chimney.
  • Avoid using bends if at all possible.
  • If working to the current Document J, do not run horizontal flue more than 150mm horizontally into the chimney from a back outlet appliance. If following the new BS EN 15287-1, the maximum distance is 450mm.
  • If possible, avoid positioning the chimney externally. If it needs to be positioned externally, use a twin wall flue system.
  • Do not be tempted to use non-BS EN certificated flue and chimney systems (Our Ultraflex liner  is thoroughly tested & certified). They may only last for a short time and will have to be replaced by the correct product. The long-term cost of using non-approved products is at least twice as expensive. Additionally, the use of non-approved products is illegal.
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