FLUE SYSTEMS
5. WIND EFFECTS ON BUILDINGS
The following drawing shows the general high and low pressure areas on buildings.
Flues should not be terminated in a high pressure area.
ROOF PITCH OVER 30° | ROOF PITCH OVER 30° | FLAT ROOF | ||||||
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W I N D
HIGH | LOW | HIGH LOW | HIGH | LOW |
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6. IMPORTANT NOTES
Do’s
6.1Ensure that when an appliance is fitted to any chimney system, that it is inspected and tested for soundness so that any defects are rectified or a new flue system provided if the soundness is in doubt.
6.2Ensure that the flue system is always installed and supported strictly in accordance with the manufacturers instructions.
6.3Ensure that all joints are properly, securely and efficiently made in accordance with the manufacturers instructions.
6.4Ensure that the flue pipe connections from the appliance rise vertically for at least 600 mm (24'')before any change of direction is contemplated. The reason for this is that the initial draught is crucial nearer the appliance because of the higher flue gas temperature. Any horizontal or angled runs at the bottom of the flue will create severe restriction to the gas movement and affect appliance operation.
6.5Try to construct the chimney vertically all the way to the terminal.
6.6Ensure that no part of the flue is installed at an angle more than 45°/135°
6.7Ensure that the flue diameter is not less than the appliance outlet.
6.8Ensure that the effective vertical height of any chimney with bends is at least twice that of the horizontal distance between appliance and terminal.
6.9Try to position the chimney inside the building to avoid excessive cooling and risk of condensation.
6.10Ensure that the chimney is installed and located in accordance with building regulations and Building regulations and British standards, particularly the distances from combustible materials are required.
6.11Remind the householder that a chimney and an appliance must breath, which is why a permanent supply of combustion air must be provided and kept clear of obstructions.
6.12Advise the householder to have the gas appliance regularly and expertly serviced.
6.13Ensure that if a gas flue block or mixed system consisting of gas flue blocks and prefabricated gas vent is constructed to avoid constructional faults.
6.14Ensure that the flue is terminated in accordance with Building regulations.
Don'ts
6.15Use single walled galvanised ducting as a flue system for any domestic gas installation.
6.16Use non insulated flue systems externally.
6.17Allow clothes, furnishings or any combustible material to come into contact with any flue pipe.
6.18Use bends if they can be avoided.
6.19Run horizontal flue anywhere in the system.
6.20Position the chimney externally if it can be avoided.
6.21Be tempted to use inferior materials for the flue system; they may only last a short time and replacement would be costly.
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