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Understandably, the recent tower block tragedy in London has resulted in unprecedented levels of scrutiny around the specification of materials used on refurbishment construction projects. John Hamnett from CFCM Ltd says that the issue of maintenance should also come to the fore
aintenance isn’t the first thing you think about in respect of flue and chimney systems. After all, they are essentially a series of stainless steel tube lengths and
elbows that are connected together to enable exhaust gases from boilers and CHP units to escape safely from buildings out into the atmosphere. Basically, you fit them and forget them. But nothing could be further from the truth because they need servicing, ideally at the same time as commercial boiler systems. Why? Because leaks, corrosion, implosions and blockages
Don’t fit and forget M
(see images) are all-too-common occurrences, which, if not addressed, pose a range of risks, including fire. In our experience, there are three main reasons for this: boiler
breakdowns, badly designed flue systems (including the wrong specification of flue system for a boiler) and biomass boilers. Biomass boilers do make commercial, economic and
environmental sense for a lot of organisations because of the notion that the wood chip used as fuel burns to nothing – making the boiler almost maintenance free. Schools and colleges in particular have been big adopters of biomass boilers – lulled by the expectations of a more cost-effective way to provide heating and hot water. However, in cases of biomass boilers breaking down, it has
became apparent that wood chip is the culprit. Firstly, it doesn’t actually burn to nothing as there is a build-up of fly ash. And in some cases, we’ve seen up to half the diameter of a flue clogged up (see image on right). The second problem is that if the pellets are damp when they
are burned, the combustion process creates both soot and, more worryingly, creosote – which sticks to the sides of flue systems posing a serious fire hazard.
What’s in a maintenance inspection?
Good flue systems should be maintained annually as part of the O&Ms, but if any of the above is cause for concern, then the first thing our inspection and cleaning teams do is check the CE
designation chart to identify if the system is actually what it’s supposed to be. I say this because you’d be surprised at the number of installations we come across where the paperwork doesn’t match up with the system. And another giveaway is that poorly designed systems don’t have regular breaks to allow for easy maintenance and cleaning access. Once a visual inspection has been carried out, with particular emphasis on joints and seals, a process of power sweeping removes all debris, soot, fly ash and creosote. All work is signed off in line with our ISO 9001:2008 accreditation and current regulations, such as British Standard 4076:1989 on the maintenance of mast and free-standing chimneys.
TELL TALE SIGNS
Because flues are enclosed systems, it’s hard to tell if there’s a problem, but here are three simple signs that there may be an issue: 1. Water marks – particularly on ceilings or, in the case of offices and other buildings, on the square tiles of a sus- pended ceiling. This is indicative of water leaking from the casings and furnishings. Most people forget that water vapour is an intrinsic part of the exhaust gases carried away from a boiler. 2. Furred joints – the acidity of the water vapour can cause corrosion over time, and the joints of a flue system are the most susceptible. The appearance of white or green fur around joints is a good indicator that mainte- nance is required. 3. Blocked drains – they can pose a serious risk to the life expectancy of a flue because, if drains are left un- cleansed and blocked, it can soon build up and deterio- rate seals in joints. Over time, it can also cause rapid corrosion to the inner liners, which, again, can cause products of combustion to leak from the system.
NATURALLY INSPIRED EFFICIENCY
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• August 2017
www.heatingandventilating.net
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