Chimneys & fl ues Fig 3 The Supra® chimney system can be used for many


varied applications, for example for effi cient Spray Booth ventilation. There is no such thing as an off -the- shelf solution –as buildings vary too much in structure. SFL’s technical team can work with you on eff ective solutions for Spray Booths in school science and DT laboratories, Colleges or Universities as shown in this recent project where SFL’s premier turnkey solution provider, FBS Flue & Chimneys choose the Supra® 500mm diameter chimney system, complete with roof- mounted galvanised jet cowls for the installation of two state-of-the-art Nukeson Wet Spray Booths. (Fig 2) The project was a successful collaboration between King Welsh, FBS Flue & Chimneys, Tarc Solutions, Eco-Nexus and University of Plymouth.


Flue route and confi guration


with stringent product standards. For System Chimneys the product must be CE marked to BS EN 1856-1 and type tested to the products performance classifi cation as detailed under BS EN 1443 – Chimneys – General Requirements.


Positive and negative pressure chimneys


Chimneys traditionally operate under negative pressure, but many now function under positive pressure conditions. Understanding the chimneys performance designation system to BS EN 1443 helps in selecting the appropriate chimney for condensing and non-condensing appliances. SFL’s NOVA® twin- wall, insulated stainless steel chimney system, is suitable for condensing and positive pressure applications and is specifi cally designed to meet the demands of the latest high-effi ciency heating appliances as well as traditional gas and oil-fi red combustion equipment. SUPRA® is SFL’s single wall stainless steel chimney system designed with the commercial installer in mind. Pre-fi tted seals make it a go-to product for many commercial condensing and positive pressure applications. In many installations these two systems can be


combined, such as in this recent educational building case study, (Fig 1) where the existing chimney system had passed its life expectancy. One of SFL’s premier turnkey solution providers, JRF Chimney Specialists, successfully installed a 250mm Nova® and Supra Plus® chimney products to replace the existing chimney systems. The Nova (100-350) systems is EN1366-13 tested and SUPRA® is an engineered system capable of meeting the demands for condensing and positive pressure applications, so the perfect combination.


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Flue routes should ideally be straight and vertical, minimizing bends that can hinder performance. For natural draft appliances, a vertical rise of 600mm before any change in direction is recommended. Additionally, fl ues should allow for easy cleaning, particularly at bends, using swept elbows with inspection points. As shown in this recent project, the route taken by the fl ue can have a signifi cant impact on performance. The straighter and more vertical the chimney the better. In all cases a chimney sizing calculation should be undertaken to EN13384-1/2 to verify the performance of the installation.


Construction and support


Chimneys require proper support throughout their length, maintaining safe distances between chimney and combustible materials is crucial. When entering a masonry chimney, fl ue pipes should ideally incline upwards at 45°.


Termination and emission dispersal


The purpose of the Clean Air Act and the Environmental Protection Act regulates how fl ue gases can be dispersed, and the Clean Air Act Memorandum is one solution used to calculate the required height of a chimney. Chimneys must terminate where combustion products can disperse safely without causing harm. Chimney height is one of the main characteristics used, by local authorities, to control the discharge of emissions into the atmosphere. The required discharge height is calculated to minimise the impact of emissions into the environment and not be prejudicial to public health. The calculations used to determine the chimney


Sources


https://www.bfcma.co.uk/commercial https://www.sfl chimneys.com/commercial/applications/ https://www.sfl chimneys.com/brand/supra/ https://www.sfl chimneys.com/brand/nova-commercial/ https://www.sfl chimneys.com/brand/europa/ https://www.sfl chimneys.com/commercial/spray-booths/ https://www.sfl chimneys.com/case-study/edinburgh-generator-exhaust-system-product-europa/ https://www.sfl chimneys.com/case-study/educational-building-west-of-scotland-product-nova-and-supra-plus/


height considers the type of fuel, the maximum rated input of the appliance, topography, environment and proximity to other buildings. A good case study for this can be found in a recent


project in Edinburgh. (Fig 3) Along with SFL, JRF Chimney Specialist were asked to recommend a solution to improve the existing exhaust system, the current discharge location was causing issues with air quality for the higher surrounding buildings. By relocating the termination location to ensure it discharged above the higher adjacent buildings, the Flue and Chimney specialists, JRF successfully enhanced the safety and effi ciency of the system as a whole, while ensuring compliance with the Clean Air Act requirements. The discharge velocity of the emissions from a


chimney is another important factor in determining how readily emissions are dispersed. The higher the discharge velocity the better the dispersion rate. Adjacent buildings can also have an impact on the required chimney height and must be taken into consideration when calculating the chimney height. The objective is to achieve an eff ective and safe chimney discharge height, rather than a minimum discharge height.


Twinning boilers and concentric chimneys


Twinning boilers into a common chimney manifold requires competent design and installation in accordance with BS EN 13384-2:2015+A1:2019, and may require local authority notifi cation. Biomass appliances should not be combined with gas or oil fl ue systems. Concentric chimneys can mitigate downdraught issues and must adhere to specifi c installation requirements in accordance with the appliance manufacturers installation guidelines.


Conclusion


In summary, selecting and installing fl ues and chimneys involves careful consideration of materials, design principles, and regulatory compliance. Adequate insulation, proper sizing, and attention to detail in construction and termination are critical for safety and effi ciency. SFL are committed to off ering industry-leading technical support, throughout the complete process of design, manufacture, and supply of every project. Our experienced team are on hand to assist at every stage of the process. From initial product selection to fl ue routing and calculations. From complex header confi gurations to large-diameter stacks, we can accommodate every requirement for any application. www.sfl chimneys.com


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