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HPM-04-APR-2016

SPECIALREPORT WWW.HPMMAG.COM Got a story? Ring us on 01732 748041 or e-mail twood@unity-media.com Real fires offer real life practicalities Real fires are making a comeback, with homeowners looking for an attractive centrepiece that is more than just a source of heat. However, part of achieving a durable installation for the long-term is ensuring chimneys are designed to combat potential acid corrosion. Paul Wydell, of Hepworth Clayware, explains... In the light of the growing popularity for real fires such as log burners and multi-fuel burners as a beautiful addition to homes, it is important to also bear in mind the practical considerations which can severely affect a chimney’s performance and durability. Acid corrosion – which can occur even in correctly specified chimneys due to how fires are operated – can lead to structural deterioration of the flue and chimney lining. While real fires can enhance any home, in order to ensure a long service life the design of flues and chimneys needs to go beyond their basic role of safely venting potentially harmful products of combustion to the outside of a building. Flues should also be specified correctly to avoid the potential risks of condensation forming from sub-optimal use or poor chimney construction. EXHAUST GASES When high temperature exhaust gases are present in a flue it should be operating above the dew point with no condensation, this is known as ‘dry’ conditions, and is supported by clay flue liners manufactured to British Standard BS EN 1457-1. However, if the correct combination of fire, flue and fuel is not achieved for an installation that was designed to be dry, for example, where a consumer is burning wet wood or a chimney is poorly built, then condensation could form in the upper and cooler parts of the chimney. This can combine with unburned products (soot) which can be present in the flue to produce sulphuric acid, which could over time corrode some flue liners despite them being manufactured to the correct standards. Correct use of dry fuel combined with a correctly designed chimney is not complete protection against condensation, as if it is only used sporadically and is cold, condensation is likely be present intermittently. Ceramic flue liners are resistant to acid corrosion which can affect both stainless steel flues and flues made of other materials such as cement bonded aggregates. Terracotta clay flue liners manufactured by Hepworth Terracotta not only offer high heat resistance, their impermeable nature resists the acid corrosion that can occur in flues designed for dry conditions. When installed, used and maintained correctly these liners are considered to provide a service life equal to that of a domestic dwelling. Terracotta is a slow conductor of heat, therefore, it reduces the danger of building elements surrounding the lining overheating such as structural timbers. Providing the minimum distances to combustible materials are observed. The only way to ensure peace of mind on potential corrosion issues caused by unburned fuel, which can seriously impair a chimney’s 32 APRIL 2016 HEATING & PLUMBING MONTHLY durability, is to choose a liner material which does not corrode when installed correctly. Therefore, installers need to ensure that they are specifying the right products for a particular installation. Correct maintenance of chimney flues is essential for all types of chimney to ensure it is working correctly throughout its service life. There is an urgent need to educate consumers who may have switched from using a combi gas boiler for years to a solid fuel appliance of the need to have their chimney swept regularly by a registered chimney sweep to prevent potentially devastating chimney fires. Terracotta clay flue liners are manufactured to tight tolerances enabling easy and accurate assembly and in square and round profile options to suit the particular appliance. The high quality products are readily available from major builders’ merchants and Hepworth Terracotta has a dedicated technical team on hand to answer any queries regarding installation and specification. Manufactured in Derbyshire using local clays, Hepworth Terracotta also presents the opportunity to specify a sustainable flue liner product made from natural materials with low vehicle miles, a high recycled content and a long service life. As consumers look to create a warm heart for their home, Terracotta offers a solution which will safeguard the installation for the long-term. Hepworth’s hallmark of precision manufacturing ensures clay is fired to perfection Terracotta is a material which resists the effects of acid corrosion, extremes of temperature, weathering and other environmental factors enquiry number 125


HPM-04-APR-2016
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