Feature
class production facilities. “The product designs are continuously
improved by large Research and Development teams with
excellent testing facilities and laboratories. Furthermore, energy
efficiency is a core design feature of VRF equipment, and this is
evident in the compressor and heat exchange technologies used
in these products.”
In terms of performance, the start-up power requirements
are extremely low due to the inverter compressors. “The
majority of air conditioning applications have varying building
load profiles and varying occupancy, this, coupled with
varying ambient conditions is ideal for VRF equipment which
provides excellent energy efficiency at part load conditions,”
he says. Aphane adds that the system is easy to install,
maintain and replace “because one thing that consumes a lot
of energy is the running of the compressor so if you slow the
compressor when reaching the required temperature then
definitely it'll reduce consumption.”
The performance of these systems
could be one of the reasons why such
systems are popular.
VRFs are
versatile as
they can be
installed in
any space.
VRF systems come with different offerings. “There are two
options that clients can choose from, heat recovery and heat
pump,” says Brotherhood.
• Heat Recovery offers simultaneous heating AND
cooling from one system. “Free” heating and hot water
production by transferring heat from areas requiring
cooling (heat recovery) resulting in maximum individual
comfort in all areas. “Running costs of VRF heat recovery
systems can be 30 to 40% lower compared to water fan
coil systems,” he says.
• Heat Pump VRF systems can be used for either heating
OR cooling operations from one system. These systems
42
RACA Journal I April 2020
have no individual indoor unit controls. “Further to
this, one must choose between an Air-Cooled or
Water-Cooled outdoor system,” he says. An air-cooled
outdoor system is fast and easy to install with no need
for additional components like pumps, cooling towers,
etc. It also has a low maintenance cost. Operation
ranges from 25 – 52°C. Condensers can be installed both
outdoors and indoors.
A water-cooled system is installed indoors offering protection
from the outdoor elements resulting in high longevity,
especially corrosion protection in coastal areas or in high
chemical environments. It is mainly suitable for high-rise and
large buildings because of the nearly unlimited possibilities
of water piping. “This system is not affected by outdoor
temperature/climate conditions. It also has lower refrigerant
levels thanks to the limited distance between outdoor and
indoor units,” Brotherhood adds.
Chettiar talks of a hybrid rooftop unit, a solution that he sees
fit for a variety of commercial and light industrial applications.
“Such a unit comes about when VRF units are coupled with
AHUs. This solution offers the clients applications of specific,
cooling, heating, humidification and dehumidification units as
well as heat recovery wheels and with various filtration options
to suit site requirements.
VRF AND THE KIGALI AMENDMENT
Industry has shown determination in offering sustainable
products that serve the environment well, through various
engagements around the world that look at phasing out
harmful refrigerants. Chettiar says that this is because the
majority of the brands are in Europe and understand the need
of having such a solution. “Refrigerants like R32 and R466A
which have a low global warming potential (GWP) are being
introduced by the different brands. New hybrid units with R32
as the primary circuit and H 2 O as a secondary circuit have also
been introduced.”
“Our development of a VRV with a lower GWP refrigerant
will offer significantly enhanced environmental performance
compared to the conventional models currently available in
the market. Whilst today R410A remains the best solution for
VRV systems, the latest technological advances are now set
to make the development of an optimised and specifically
designed VRV system with low GWP and enhanced
refrigerant containment possible. Daikin will be launching
smaller system capacities operating on R32 in the near
future” Brotherhood shares.
Overall, VRFs have adapted with the changes in the industry,
Aphane is confident that changes regarding the phasing down of
HFCs presents opportunities for design. RACA
www.hvacronline.co.za