VENTILATION/HEAT RECOVERY
Effective service every time W
ith the Environmental Protection Agency (EPA) stating that indoor air can sometimes be two to five times more polluted then outdoor air, it is important to install an effective ventilation solution to ensure the
health of building occupants. Here, Robert Dennis, product marketing executive at Airflow Developments discusses the issues to consider to achieve the expected performance. In order for a domestic property to meet the latest building regulations
there must be a ventilation system installed as required in Approved Document F1, Means of Ventilation. This is to ensure that excess moisture and indoor air pollutants, created from everyday activities such as cooking, showering or cleaning, are properly extracted. However, while an installer may specify the correct ventilation system based on a manufacturer’s product data sheets, this will not always be reflective of the installed performance in-situ. Therefore, it is important to do some investigation. Some ventilation manufacturers may claim that products comply with the latest Building Regulations, however in some cases the proposed performance might only be in regards to a free air environment. Therefore a fan may not perform to the required standard when installed as part of a system, which could mean that even though ventilation is installed, there could still be a build up of moisture and pollutants. When looking for an extractor fan, it is critical to check the product’s installed performance data, and pay particular attention to the fan’s performance graph, known as the fan curve. These graphs show the flow rate against the static pressure, providing installers with a greater understanding of the installed performance and the amount of ducting that can be used. In addition, the Domestic Ventilation Compliance Guide provides tips that can
help avoid an incorrectly installed system that could severely impact the performance of a fan. For example, if flexible ducting is being used, it needs to be pulled taut to 90% of its maximum length and cut to a suitable length. If this is not completed correctly flexible ducting can become squashed or crushed, which will create an increased system
pressure that the fan cannot overcome. Again, this can mean the required installation rates will not be met. To test a fan’s installed performance, installers should use a powered air flow meter. These instruments use an inbuilt fan to equalise the back pressure of the measuring device so that accurate air flow measurements are possible without further complex calculations. Furthermore, on-site testing should follow a ‘Best Practice’ process and adopt air flow measurement, Method A – The Unconditional Method – using a suitable UKAS certified measuring instrument, generically referred to as a ‘Powered Air Flow Meter’ or ‘Zero Pressure Air Flow’. Further information on this method can be found in NHBC Building Regulations Guidance Note G272a 10/13 and BSRIA’s ‘A Guide to Measuring Air Flow Rates’ document BG46/2015. Installers should ensure the ventilation system specified within a customer’s
property is going to perform in accordance with Building Regulations. It is vital to take into account installed performance data, and ensure the correct, best practice installation and commissioning process is followed. This provides customers with a reliable and professional service that helps to achieve excellent indoor air quality and also reduce long-term maintenance and servicing costs.
www.heatingandventilating.net
October 2017
39
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