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Heat Recovery Air Conditioning Technology Moves Forward with Daikin VRVIII-HR System
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Further information released by Daikin Europe NV, underlines the VRVIII-HR system’s considerable advance on the earlier VRVII-HR model.
VRVIII-HR, which is ideal for use in commercial office complexes, hotels, apartment stores, restaurants and a wide range of public sector buildings, offers important benefits in energy efficiency and cost savings to installers and their end user clients.
Many new features.
Among its many new features is the ability to connect up to 64 indoor units (40 for VRVII) to a single outdoor unit in increments of 2HP up to 48HP. Outdoor unit modules can be configured on a combined ‘multi’ basis between 18 and 48HP or in a ‘stand alone’ version from 8 to 16HP, which makes the latter the largest single unit currently on the market. VRVIII HR also offers indoor unit connection ratios up to 200% for a single outdoor module system and 160 to 130% on double or triple multi modules. Operating range is wide at -50C to 430C in cooling and -200C to 15.50C in heating.
Whereas contemporary VRF systems cease operating during defrost and oil return operations, separate defrosting of each heat exchanger on VRVIII HR multi module outdoor units and of the dual outdoor coil of single modules allows continuous heating to be supplied from the indoor units throughout defrost cycles.
Refrigerant leakage prevention is ensured by the use of brazed joints in place of flanged and flared connections before the shut off valves as well as by brazed pressure sensors and electronic gauges instead of sensors and gauge ports. There is also on average, 10% less refrigerant charge compared to a similar sized VRVII system.
The ‘night quiet’ mode is also important and can be set automatically to cut in 8 hours after peak daytime temperature and run for 10 hours before reverting to normal operating mode. Alternatively, starting and ending times can be input manually via a time clock or both automatic and manual modes can be combined as required. During the night quiet cycle, operating sound can reduce to 45dBA.
Design flexibility is enhanced by the incorporation of a powerful new inverter driven outdoor unit fan, which provides a higher ESP of 78.4Pa (58.8Pa for VRVII). The outdoor unit footprint is less than similar capacity VRVII models and piping lengths are the highest in the industry at 1000m (total system), 165m (maximum run), 90m (maximum level difference) and 90m (longest branch).
In the event of a malfunction automatic back up is provided on outdoor models, enabling a twin compressor single module to operate on a single compressor until the fault is rectified and continuous operation for 8 hours on for example, two out of three multi modules, after the remote controller has been reset.
Automatic charging and checking
Consideration of forthcoming ‘F’ Gas regulations is reflected in VRVIII’s capability for refrigerant containment monitoring during both charging and system operation. This important facility enables the amount of additional refrigerant charging during commissioning to be controlled automatically. Charging ceases as soon as the correct amount of refrigerant is transferred and refrigerant cylinder ‘empty’ status is indicated on the remote controller.
Improved efficiency
Efficiency improvements stem from the application of new technology, resulting in a 3 – 10% increase in airflow rates from the new aero spiral high output dual DC fan and grille assembly and low pressure loss bellmouth. Also, the new 3 wall heat exchanger increases effective coil surface. Friction losses are also reduced by virtue of its high thrust mechanism, which reduces operating noise as well as generating improved efficiency.
