The chimney should remain as straight as possible through its vertical run to assist flow. Should it be necessary to offset a chimney run the following guidelines should be adhered to:
Gas: An offset no greater than 45° to the vertical, with a run between the bends (B) not exceeding half the overall height of the chimney (A) should be maintained.
Oil - Solid Fuel: An offset no greater than 30° to the vertical, with a run between the bends not exceeding 20% of the overall height of the chimney should be maintained.
In both instances a maximum of two bends in any one chimney run should be used. A vertical rise of 600mm should be allowed immediately above the appliance before any offsets. Reference for both guidelines can be found in the Building Regulations Doc J and relevant British Standards on installations.
For solid fuel appliances, BS7566 Parts 1, 2, 3 and 4 recommends use of an open terminal for chimneys up to 200mm diameter. Rain ingress should not be significant, but drain components can be fitted. Above 200mm a covered terminal can be used, and for all oil and gas installations. Mesh carries the risk of sooting and requires regular cleaningto avoid blockage particularly with oil and solid fuel.
Provision for sweeping, cleaning and maintenance
Provision should be made for inspecting and cleaning the chimney. This is particularly important on solid fuel applications. It is recommended that chimneys serving solid fuel appliances be swept as frequently as necessary but at least twice a year. Choose an access component suitable for your installation unless cleaning/inspection can be done through the appliance.
The room carrying the appliance should have an air vent either direct to an external air source or vented into a room that has an external vent direct to an air source. This is required to provide adequate air supply to allow the appliance and flue to operate efficiently. These requirements are specified in the Building Regulations (Document J) also by CIBSE and BS5440.
Provision for condensate disposal (subject to appliance manufacturer recommendations) Normally solid fuel and atmospheric gas and oil appliances will not need a drain unless rain ingress is significant. Most condensing appliances however need provision for drainage. As a rule of thumb a condensing boiler produces 1 to 1.5 litres of condensate per hour per 10kw of input. This is a significant amount of acidic liquid which must be drained from the system. Choose appropriate flue drainage components, normally fitted at the base of the stack and close to the appliance outlet. A 5° slope on horizontal runs is advised, using the appropriate 85° or 40° bend and 95° tee.
Connection to an appliance which is not connected to the fuel supply, may be carried out by a competent person. However, connection to an appliance that is connected to the fuel supply must be carried out by a Gas Safe Register (gas) or OFTEC (oil) registered installer. The flue system must be installed to comply with Building Regulations Document J (in England, Wales & Northern Ireland) Regulations for Scotland. The installation must also comply with BS7566 pts 1,2,3,4 for oil flues and BS5440 pt 1: 2000 for gas flues up to 70kw.
The joint is locked by rotating the upper section clockwise. To secure the joint, the locking band supplied with the female end of all components must be used. To allow alignment, the female section of the locking collar on tees and elbows have no locating flutes. For this reason these joints MUST be secured using the locking band. For condensing applications a lip seal gasket must be fitted in the bead of the projecting liner spigot of every joint. The gasket should be fitted dry and lubrication applied to the internal of the socket into which it is to be assembled.
An ICID adjustable length allows adjustment from 75mm up to 250mm. Assembly is achieved by fitting the adjustable length over the preceding pipe. Remove insulation as necessary and secure when desired length is achieved using jointband supplied. The adjustable is not load-bearing, therefore adequate support must be provided immediately above.
Connection to ApplianceAlways use an appliance connector, sealed using fibre rope and fire cement or high temperature sealant. The inner liner should not project below the appliance outlet spigot and can be cut to length if required.
Appliance RemovalUse of a pipe length and an adjustable length immediately above the appliance enables removal of the appliance later without dismantling the full system.
Painting of ICIDIf required to be painted, simply clean the surface with a solvent cleaner (White Spirit), apply a coat of primer and a top coat of high temperature paint e.g. enamel. Extreme care must be taken when cleaning with solvent to ensure that it does not come into contact with the insulation within the cavity.
Recommended distances to combustibles
In accordance with building regulations it is essential that the required distance to combustible materials is maintained throughout the chimney system. For gas and oil this is 50mm and for solid fuel 75mm. ICID support components provide this as standard.
The weight of a chimney system is considerable and requires independent support. No weight should be taken by the appliance. A wall support at the base of the stack will support up to 10m of chimney, or in an inverted position, up to 15m. Wall supports can then be used as an intermediate support every 10m thereafter. Alternatively, on internal systems the weight is held by using a support plate and clamp fixed on top of the first floor/ceiling joist. A Firestop plate is also required fixed to the ceiling below. In a normal house, when passing through the second floor the only requirement is two firestop plates because the system is adequately supported at first floor level. Wall brackets and roof brackets are not load bearing and give lateral support only. Wall brackets should be fitted every 3m and at any offsets to ensure the system is rigidly supported . Where the flue is free standing above the roof and its height exceeds 1.5m beyond the last support or the roof a guy wire bracket must be used, and every 1.5m there after. Alternatively, a height of up to 4m can be achieved unsupported with the use of an extended locking band at the joint immediately below and every joint above the roof level.
Testing before use
This is done by means of flue flow test as described in BS5440:Part 1-2000. It can be summarised as follows:- After a visual and physical check of the joints in the system, and ensuring an adequate air supply for combustion has been provided, close all doors and windows in the room in which the appliance is to be installed. It will be necessary to introduce heat to the flue system for a minimum of 10 mins. and possibly up to 30 mins. using a blow torch or similar. Position a smoke pellet (providing a performance of 5m3 of smoke in 30 secs. burn time) at the intended of the appliance. The test is satisfactory if there is no significant spillage from the appliance position, no seepage over the length of the system, and discharge only from the terminal. If these conditions are not met, the test has failed and all faults must be rectified and the system retested before connection of the appliance to the fuel supply. In the event of any further problems, reference to BS5440:Part 1-2000 must be made.
Under normal operating conditions and providing the system is installed correctly, it should last the lifetime of the appliance which is normally 10 to 12 years. ICID carries a 10 year conditional warranty. The conditions are that the chimney is correctly sized, installed, and properly maintained, burning only approved fuels in accordance with the Rite-Vent and appliance manufacturer's instructions. For recommended fuels listings, please refer to the HETAS guide, or by contacting the Solid Fuel Association (Tel: 0845 601 4406) or appliance manufacturer's instructions. Warranty registration details are provided with installation instructions for completion and registration with Rite-Vent.
It is essential that the flue way be kept clear at all times in the interest of good practice and health, safety and appliance performance. The system should be checked regularly during the appliance maintenance. (Refer appliance manufacturer's instructions).
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