Feature the system can continue to run . This is applicable to both indoor and outdoor units , as well as condenser banks that are typically installed with a master / slave configuration .
“ Even if anything happens to your master condenser ’ s compressor in your set , this will be isolated , and your system will still continue to operate with an instantaneous switchover to the slave . Because an under capacity now occurs , an alert via SMS or email can be set up to notify the facility manager or technician that something is wrong . So , communication and control has seen defined improvement in IoT and AI methodology for new VRF models such as our sixth-generation unit called GMV6 . VRF has reached the point where the biggest improvements are now in electronic technology . One particular challenge for installations in this system type is at the commissioning stage when addressing the units or allocating an address to each unit is done . This can be executed in a manual way , however Gree has developed advanced technology to achieve this electronically with the intention of saving time where many units are installed in a building . We are able to simply plug in a laptop into any of the connected units and run the self-addressing programme to fulfil this function . All of the data is then saved in the cloud ,” Ndelu adds .
Marco Ferdinandi , marketing director at Mitsubishi Electric Airconditioning SA expresses a different view on unit addressing , “ Yes , one of the challenges in a VRF system is the addressing . In our view though , the manual addressing function is the better option . All the components have a relationship with each other and communicate needs or status via this address . ( Physical addressing is the process of going to each unit and setting the address via a group of dip switches ). Although there is the functionality to do this electronically , the SA power supply as mentioned by Sibusiso being what it is , shuts down at various times and at varying frequencies . What does occur with electronic devices is that they often go out of sync so to speak , and when power is restored , the units start up and the process to get all these units to identify themselves again must be completed . We all know about ‘ technology gremlins ’ that change things in the system because of timing delays , and so can lead to the system not receiving the correct data by for example the swopping of units . This cannot happen with manual addressing and is the reason it is a preference for us .”
Another consideration that makes VRF attractive is that no high-capacity dedicated power supply is required , which can be extremely costly in a project . The technology can be installed using electricity supply that is already part of a building , while consumption is determined by variable load . It is also unlikely that all units will operate simultaneously .
“ The number of indoor units that can be linked to a single system depends on supplier to supplier , but generally speaking most manufacturers can connect 64 indoor units on one system .
© Daikin South Africa
You could control eight systems from one controller and linking systems you can connect up to 256 indoor units in a building and taking that further to an internet-based system program , you can link up to 4 096 indoor units across different buildings . Samsung also incorporates wind-free technology that is unique by maintaining room temperature once the set point has been reached and does not start and switch off like other units . You can imagine with the number of possible units in a building the power savings this can achieve ,” adds du Plessis .
Older systems can also be retrofitted by adding VRF components to them without the need to remove the whole old system . This is particularly useful for example in air handlers where a coil unit can be installed within the AHU and connected as a specific unit to the VRF system . Secondary coils can also be fitted to older systems that cannot function on generator power when there is a power outage due to electrical capacity needs of the older system , while VRF requires significantly lower power and could keep the HVAC system operational in those conditions – this application could include older hospitals or clinics .
VRF has also become a popular choice because of the fact that legislation has limited the amount of refrigerant allowed per system . This is particularly relevant to occupied spaces so commercial building like hotels can be fitted with several individual systems that serve certain areas or floors to meet the requirement . The limitation you do have , however , is that in cases of a lot of indoor units , you have the equivalent requirement for leak detection , and in very large installations this sometimes becomes impractical from a feasibility aspect .
“ The push to implement our two-pipe system has been a unique offering for Mitsubishi Electric Airconditioners . All other suppliers implement a varied configuration around a three-pipe system to achieve the heating or cooling required . Our further
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Daikin kickstarted the refrigerant transition by pioneering the introduction of R32 into South Africa .
www . hvacronline . co . za RACA Journal I July 2021 21