AIR CONDITIONING Airstage J Series Mini VRF installed inside
for the increasing need to reduce buildings’ heating and cooling load requirements. The range from Fujitsu has recently expanded, doubling in capacity and now offering up to 50kW from a small, lightweight chassis. This expansion has been targeted at installations with restricted mechanical plant space, where a building’s required load would usually lead to the use of a larger system.
The transfer of technologies and functions commonly found in maxi
VRF units such as adjustable external static pressure and low noise modes have facilitated the use of mini VRF installation indoors. Improvements in inverter compressor and oil return have expanded an already flexible system design, to one that can be applied to serve buildings with large elevation differences between outdoor and indoor units. This means that with an acceptable 50 metre difference, pipework can span approximately 12 floors between one unit and the other. This difference of elevation is not only possible between outdoor and
Research and Information Association (BSRIA) data classifications. It is more commonly known to be a unit that discharges air from the front opposed to the top. The mini VRF has grown to offer a wealth of benefits to suit modern
design challenges across an array of applications. As part of the design process, project consultants are looking for ways to maximise space. Compared to most traditional-style maxi products, mini VRF units have roughly 45% smaller footprints, are around 50% of the volume and up to 30% lighter.
This overall reduction in size and weight also benefits installation
engineers because units are easier to transport, manoeuvre through a building and lift into position. These design differences also result in cost saving benefits, especially
when this means that cranes, as a means of lifting a unit into position, are not necessary. Starting at 12kW and ranging to 20kW; the mini VRF is an ideal solution
indoor units, but also between indoor units on the same system. System balance is assured through developments of each indoor unit’s expansion valve regulation and tighter refrigerant distribution control strategies – a benefit equal to any maxi VRF system on the market. Coupled with adjustable external static pressure that allows air to be ducted on and off the unit, an ‘outdoor’ unit can be installed within a plant room or even within a tenant’s space - inside a dedicated cupboard for example. Air ducted through an external wall and units are capable of overcoming up to 60 Pascals in air pressure loss. We talk about design potential and direct environmental impact, but the
mini VRF has also found niches within the market by negating refrigerant leak detection on certain projects and helping F-Gas related quotas. Reduction in pipe diameters has reduced the refrigerant charge used within a system by approximately 25%. The impact on F-Gas quotas and leak detection thresholds is relevant to the refrigerant being used in a particular system but the reduction is still present, irrespective of the refrigerant and will always be beneficial. Are we moving away from the cumbersome maxi systems and into a period where less is more? The maxi VRF still has a solid place within our sector – the much larger modular capacities and greater number of connectable indoor units makes them an ideal solution for larger projects. But demand for the mini VRF is rising, its popularity fuelled from societal pressures concerning both local and wider scale effects. Logistics are less complicated, installation costs reduced and specification is made easier through making things smaller.
Comparison of reduction in footprint between Mini and Maxi VRF
www.acr-news.com
February 2020 23
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