PIPES AND DUCTWORK
Working out ductwork
Inadequate ductwork can severely aff ect the performance of a ventilation system, impacting negatively on effi ciency and performance. Malcolm Moss, President of ADCAS, identifi es fi ve common problem areas and off ers advice on how to remedy ductwork issues.
D
uctwork may not be top of the list when discussing a new ventilation system - but its importance to functionality cannot be understated. A ductwork system acts as the central nervous system in a building, carrying hot and cool air to areas where it is required as well as providing fresh air to improve levels of comfort. A ventilation system with poorly designed or installed ductwork will consistently fail to deliver the expected results and can’t be relied upon to improve effi ciency within a commercial building. This article will explore and discuss some of the more common issues encountered.
Poor design
It may sound obvious, but it’s very rare that any two buildings match up in terms of layout and internal confi guration. As a result, one size most certainly doesn’t fi t all when it comes to HVAC systems and ductwork specifi cation. From the early design stages, the proposed system should allow air to fl ow smoothly. Incorrect duct sizes can lead to increased energy/ running costs as the fan will have to work harder to deliver the air into the occupied space. Specialist parts of the system, such as fi re rated ductwork, should be designed, manufactured and installed by competent and professional companies. Compromising on this could be catastrophic, leading to damage to property and, in worst-case scenarios, a potential loss of life.
34 April 2018
Get the design, specifi cation, installation and commissioning right from the very start and you’ll end up with a balanced system capable of delivering effi cient airfl ow rates on a long-term basis.
Leaking ductwork
One of the major causes of ineffi ciency in ductwork is undiscovered or overlooked leaks. Incorrect installation, insuffi cient clips or clamps at the cross joints or the use of incorrect gaskets between cross joints is a major cause of air leakage in ductwork systems. Incorrect selection of fl ange cross joints or the use of inferior profi les can weaken the cross joint and increase air leakage with a knock-on eff ect on system performance and increased energy consumption as the system needs to run for longer to maintain the room conditions. As well as impacting on effi ciency, leaks can also allow outside pollutants to enter the ductwork system, compromising indoor air quality.
Even if ductwork is subject to regular maintenance (which we’ll explore in more detail later on), it’s worth keeping an eye out for the tell-tale signs of leakage. Rooms may feel unusually hot or temperatures within the building may seem uneven, with noticeable hot or cold spots. On top of this, energy bills may be higher than expected as the cooling system will
Dirt, blockages and indoor air quality Indoor air quality has become a signifi cant talking point over the past few years and it’s been suggested that up to 53% of air quality issues are caused by inadequate ventilation.
If ducts are left untouched and dirt and dust allowed to build up over time this can eventually lead to airfl ow problems and pose a health risk to occupants as pollutants, dust and other particles are circulated around the building. In worst case scenarios ductwork can harbour rodent droppings or the remains of insects. The full eff ects of poor indoor air quality are not yet known and research into the subject remains in its infancy - however, increased scrutiny into links between potentially harmful particles and a range of diseases are now being investigated in greater detail. This in turn is likely to push the conversation towards ventilation hygiene and calls for proper processes to be put in place to verify the cleanliness of the ductwork, such as the use of specialist contractors who can off er support to facilities managers.
be working harder to try and compensate for the leaky ductwork.
Leaking or damaged ductwork is a serious issue that only worsens if left unattended so it’s always worth getting it checked out if there are any doubts at all around reduced or excessive airfl ow.
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