www . refrigerationandaircon . co . za RACA Journal I June 2023 21
Feature
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1 . Multiple VRF heat recovery systems with a central controller . Two high temperature hot water modules for domestic hot water and multiple Light Commercial high wall units for two server rooms which include duty / standby operation .
Photo 1 and 2 : AHI Carriers
2 . Multiple VRF heat pump systems connected to AHUs for temperature , humidity and CO 2 control .
and the air conditioning equipment can be adapted to it . It utilises space efficiently , with no construction or space requirements .
“ There is a saving on operating cost , improved energy efficiency and ‘ green ’ certificate rating . Where there are multiple tenants they can each be individually billed and it permits remote operation and monitoring . The building owner can monitor the operation of the system and get email notifications of errors .
“ For the operator , there are various control solutions which integrate with a BMS system enabling control of off-peak electricity usage , whereby the VRF can be cut back on usage during those times .
“ For the occupants or users , there is individual control for each room or zone , operating for holiday and overtime work or temperature and humidity control according to occupants ’ comfort and it is an easy control function .
“ For the installer , on the maintenance side there ' s less installation cost if you compare it to a chilled water design , equal compressor operation meaning that the running hours on the compressors can be equalised if you ' ve got multiple compressors . It offers flexible piping installation , easier access for status check and option settings , less maintenance costs and easy maintenance , as well as precise detection of refrigerant leakage ,” says Bester .
A majority of VRF systems in the market utilise refrigerant as the heat transfer medium which has better heat transfer properties compared to water . “ Compared to chilled water systems , there are many pros and cons , depending on the application and site conditions , however I strongly agree that there is a market for both types of equipment .”
He lists the pros :
• Individual control for every indoor unit
• Individual electrical power consumption billing for tenants
• No equipment room required , and low ceiling heights are not a concern . Service shafts can be much smaller
• Easy maintenance and support from one supplier / contact point
• Maintenance costs are lower
• Low noise levels for indoor units and outdoor units
• Avoid up to 20 % energy losses due to large ducting such as for AHU systems
• Smaller piping and ducting compared to chilled water systems with the same capacity
• Light weight and compact equipment . VRF installation is approximately 40 % less expensive compared to a chilled water plant . These savings include rigging of chillers , cooling towers and AHU / FAUs
• Space saving is a major factor
• Heat recovery is easily achieved when utilising a heat recovery VRF system and the heat recovery is further enhanced with hot water modules for domestic water and air to air heat exchangers for fresh air treatment
• Backup operation available in the event of a compressor or inverter PCB failure
“ In respect of inverter compressors , the scroll compressor has been the most popular for VRF equipment . However , some manufacturers use twin rotary compressors and Toshiba launched the world ’ s first triple rotary compressor incorporated in the latest
www . refrigerationandaircon . co . za RACA Journal I June 2023 21