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HPM September 2017

option, helping them navigate around these potential pitfalls – which brings me onto the main point of this article. In recent times, Heating and Hotwater Industry Council (HHIC) members have advised that they are encountering an increasing number of unapproved flue systems and components being installed to gas boilers, most often in the form of unapproved PMKs. Potential repercussions Unless of a type/specification approved by the appliance manufacturer, such kits will provide little, if any, reassurance that the appliance and flue system will operate as intended, with potential repercussions for safety and consumer warranties. PD/CEN/TR 1749:2014 is a European technical report which classifies appliances based on the method of evacuation of the flue gases. In the UK, most commonly C1 (horizontal flue), C3 (vertical flue) 19 I N D U S T RY WAT C H and C5 (non-balanced flue/air – such as PMK’s) appliances are supplied. In these cases, the flue system is specified by the appliance manufacturer, and forms part of the testing and certification requirements at the approvals stage, for example, CE marking under the Gas Appliances Directive. It is, therefore, of paramount importance that the manufacturers’ specified flue system is utilised, in order to ensure validated levels of safety and performance. Technical instruction The appliance, flue components, or both, will come with detailed technical instruction for correct installation, including guidance on jointing, support and maximum flue lengths. Category C6 appliances are the only exception, where a proprietary flue-system is not specified by the appliance manufacturer, although they are still likely to offer advice on appropriate products and materials, for example, MUPVC pipe suitable for C6 twin-flue products. While the manufacturers’ instructions can be seen as the essential reference document, this advice is supported by BS 5440-1, stating as it does that PMKs can only be used when provided or specified by the appliance manufacturer. The Gas Safety (Installation & Use) Regulations also place an all-encompassing legal duty upon engineers to ensure that they do not modify gas appliances in such a way that results in them ceasing to comply with the standards to which they purport to comply, for example original approvals – CE marking. Gas Appliances Directive The appliance test standards used to certificate the appliance-type under the Gas Appliances Directive, include a range of appliance/flue combination tests, the results of which may be impacted by a change in flue specification. These include acceptable leakage rates from flue components, maximum acceptable flue-gas temperatures for the materials used, and also “blocked-flue” tests, which ensure the appliance does not operate unsafely in this scenario, where the specified flue-system is utilised. Also of concern to the HHIC is the potential impact on consumer warranties where unapproved flue components are installed. The repercussions range from condensate leaking externally – a potential nuisance and freezing hazard above paths etc. – to recirculation of products of combustion, risking nuisance lockout, internal appliance corrosion and elevated levels of carbon monoxide, which are all likely to invalidate the consumer’s commercial warranty where due to inappropriate materials/components. To ensure safety, reliability and to protect consumer warranties, always specify and install the appliance manufacturers’ approved flue system components to type-C gas boilers. Speedfit plumbing and heating blends push-fit with multi-seal technology for a reliable, leak-proof connection. • Grip & Seal gives a firm hold on plastic or copper pipe • Superseal Inserts create a secondary seal • Twist & Lock compression for a leak tight seal • No tools needed - install, demount and re-fit in seconds • Safe, flame-free installs insurers and homeowners will love speedfit-tech.co.uk enquiry number 314


HPM September 2017
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