www.swimmingpoolnews.co.uk
Condensation DEC 2010 SPN
59
“The basic requirement is to remove moisture from the pool room air at a rate greater than water is evaporating from the pool surface”
The Andromeda EC30 from Heatstar, utilises low energy fan technology and is designed specifically for domestic pools with surface pool covers
which are comparatively poorly thermally insulated, such as external windows. “The balance point, at which water vapour can no longer be supported, is described as the dew point.
“The basic requirement is to be able to remove moisture from the pool room air at a rate greater than water is evaporating from the pool surface. “Humidity control by introduction of outside air is possible in the UK as there is invariably less moisture content present in the fresh air than in the humid pool room air. It is also a misconception that outside air contains more moisture in the winter months – the reality is that, in the UK, the fresh air in the summer months actually contains much more moisture, necessitating increased air extraction rates during such times. The outside air during the winter months may seem ‘damp’, but this is, again, merely the ‘relative humidity’ effect at a cold air temperature.
“However, to achieve proper humidity control via outside air introduction, this process could necessitate throwing away the entire air volume of the pool room to the atmosphere once every 10 minutes! Bearing in mind the requirement to re- heat the introduced cold outside air to maintain the required pool room air temperature, the energy consumed by such a process was huge. “Given present fuel costs, such a wasteful approach would understandably prove prohibitively expensive to operate and would now be in breach of building control regulations. “Modern systems now utilise methods of active
energy recovery, generally using refrigeration technology to condense out excess humidity without the need to ‘throw away’ the warm pool air at all. Such systems also enjoy the ability to ‘recycle’ the latent heat contained within the humid pool room air back to either the air or pool water, utilising the heat pump principle.” Dehumidification by refrigeration is not, in itself, a new technology. The American inventor Willis Carrier is attributed with designing the first modern air conditioning system in 1901. However, what he actually designed was a dehumidifier. The cooled air effect we associate with modern air conditioning was merely a by- product of the function of the dehumidifier. Many indoor pools will utilise a central ventilation system fed from a dehumidification unit normally located in the plant room. Therefore, the correct design and layout of the air distribution duct channel and air outlet grilles is an important element in condensation control. Adds Paul Scott: “The air duct channel should be designed to ensure that air is discharged via grilles directly over external glass areas prone to condensation, that there are no significant parts of the pool room through which air is not being circulated and that air discharge velocity across or towards the actual pool water surface is minimal. “If condensation is to be avoided, the pool room building structure has to play its part. “If the pool room humidity level is properly regulated, condensation can still occur if there is a flaw with the design or execution of the pool hall. “Within a modern pool hall, surface condensation would not be expected to occur on any part of the structure, with the possible exception of outside glass and only then during very cold weather.
“Consider that the glass would typically have a thermal insulation value perhaps 10 times poorer than the ceiling or the walls and it should be obvious that, if you do not have condensation on the outside glass, but you do on either the walls or the ceiling, then something is very wrong with the thermal performance of those areas. “If there are any doubts or concerns, then a thermal image survey could be used to identify parts of the structure which are not thermally performing due to, perhaps, some insulation slipping out of position or outside air ingress. “All small rooms, such as toilets, showers etc, which are immediately adjoining to the pool hall, should be equipped with some basic form of heating if they are not encompassed within the scope of the climate control system for the main pool room.” spn
i FOR FURTHER INFORMATION
F CERTIKIN H&V (CALOREX) ( 01993 778855 :
www.certikin.co.uk F ESG POOL VENTILATION ( 01480 492140 :
www.esgpv.co.uk F HEATSTAR ( 01983 521465 :
www.heatstar.com F MEACO ( 0500 418458 :
www.meaco.com F RECOTHERM ( 0121 433 3622 :
www.recotherm.co.uk
HOW POOLS ARE COPING WITH CONDENSATION AND DAMPNESS
South Moorlands Leisure Centre Before the installation of a Calorex HRD30 air handling unit, the pool hall at South Moorlands Leisure Centre was plagued with condensation and damp problems, resulting in rotting windows and doors as well as unpleasant conditions for both swimmers and leisure centre staff. The Calorex HRD30 typically offers 300% heat recovery to pool water and/or pool hall air compared to just 50-60% from recuperator type air handling units. Typically, the unit is capable of removing 300 litres of water
in a 24-hour cycle – and plays a vital role in maintaining temperatures and conditions for indoor pool environments.
Contact
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