Feature
‘ SILENT COMPONENTS ’ THAT MAKE SYSTEMS WORK
Compiled by Benjamin Brits
Controllers are the core around which HVAC systems are able to provide the required outcome of temperature , pressure and humidity control while maintaining energy efficiency .
Analog controllers are some of the youngest technologies in modern day engineering . Many reports reveal the invention of these devices was around the mid to late 1960s , preceding the release of the commercial computer in fact . As progression to digital has come about with all electronic devices , there are very few elements in the HVAC / R sector today that do not make use of one or other type of this technology as an essential tool to complete a system and achieve optimal operating conditions .
The role of any controller is to execute a particular function or set of functions at a particular time and based on particular circumstances .
Sitting in a comfort cooled ( or heated ) office , visiting a supermarket or working in a high precision plant , the control methodology of any system most often does not even make it into anyone ’ s thoughts , but let something go wrong and it is the first thing that everyone will point to , highlighting the importance of these ‘ behind the scenes ’ devices .
Creating and maintaining an environment where a HVAC / R system is required , must take multiple factors into account in both the outdoor and indoor conditions and is of course , dependant on the specific application . Considerations around the main elements include all , or particular attention in , temperature , humidity , air movement , extraction and air quality that require continual management .
Each industry sector will also have differing needs - from the agricultural and food industry to data centres , to various manufacturing , commercial and medical facilities – these all demand varying outcomes , quality , and precision in order to meet their own functionality .
Application-specific control needs to also fall within an acceptable tolerance range while there are very different criteria for refrigeration , comfort environments and processing facilities – that for example require the delivery of extremely accurate system management in milliseconds – rather than seconds or minutes as acceptable in other functions . This then alludes to the range and quality of controllers available for their specific requirement as well as their capabilities and complexities .
Controller needs are further said to be a direct correlation to the asset value , and it makes sense that one would not install a R600 device in a R10-million plant or apply this logic to a billionrand processing facility . It would also be important to understand elements such as device inputs and outputs , compatibility with other sub-system controls , and other features such as connectivity or reporting .
Trend Controls
When systems are integrated , each one operates more efficiently .
A CLOSER OVERALL LOOK AT CONTROL As we have established , the built environment has a range of controllers that are specific to managing the built environment , and this is the same for refrigeration or any industrial process .
Why have all these different ranges of controls you may be wondering ? Why isn ’ t there just one type of control that can be applied across the board ? Well , the answer is quite simple and relates to the aforementioned link of a price point against the asset value , but further the more complicated a system becomes , the more complexity is required , and the greater the possible control to be implemented ( sometimes extremely sensitive control is demanded ).
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RACA Journal I September 2021 www . hvacronline . co . za