CHILLERS
As the storm clouds gather
With multiple technologies in its product off ering, Klima-Therm has a unique vantage point to refl ect on the current debate about the future of VRF/V air conditioning. Tim Mitchell of Klima-Therm considers the clouds gathering and how this could benefi t promising alternatives.
S
ince it was fi rst introduced here in the 1980s, Variable Refrigerant Flow/Volume (VRF/V) air conditioning has been a runaway success. The approach, based on a distributed DX system with refrigerant piped around a building, has taken signifi cant market share from more conventional forms of cooling and heating buildings as its range of application has grown.
With multi-plexed systems, reasonably long pipe runs and sophisticated controls, the technology has eaten into the medium-size and even larger end of the chiller and fan coil market. At the other end of the scale, the development of compact VRF/V-style systems has begun to replace splits and multi-splits in smaller projects.
Massive R&D investment by the Japanese and, latterly, South Korean and Chinese manufacturers has kept VRF/V pre-eminent in certain types of buildings, delivering comfort, fl exibility and effi ciency at a price point that would not be possible with chillers and boilers.
In the UK today there are around a dozen manufacturers vying for a share of the lucrative VRF/V market. However, there are now emerging some potential downsides to VRF/V technology that raise concerns about its long-term future. Manufacturers and proponents of the approach have long-wrestled with VRF/V’s Achilles’ heel – the potential risk associated with circulating large quantities of refrigerant around a building. EN378 places strict limits on the maximum concentration of refrigerant that is allowed in an occupied space in the event of a leak. With some large projects requiring very substantial volumes of refrigerant, this continues to be a concern. Compliance depends on project- specifi c mitigation involving system design and technical safety additions, such as refrigerant leak detection and ventilation, to meet the requirements. While this issue can be successfully managed on a project-by-project basis, new
28 August 2018
uncertainties in relation to refrigerants cast a potentially more worrying shadow over the future of VRF/V. The latest revisions to the F-Gas Regulations introduce strict quotas on the sale of high GWP refrigerants over the next decade or so. R410A, the refrigerant on which the current generation of VRF/V air conditioning systems operate, is classed as a high GWP substance – and is now fi rmly in the crosshairs of the F-Gas phase-down.
There are serious supply shortages in the availability of R410A as the F-Gas quota system begins to bite. This has not been helped by a worldwide shortage in manufacturing capacity for R125, a key component of the refrigerant. The result has been sharp and we have seen regular increases in the cost of R410A, in the order of a 30% rise per kg every few months.
Due to the quantity of refrigerant used in a typical VRF/V system, this has major implications for both the initial cost of equipment and any top-up refrigerant required during servicing as a result of leakage.
Many air conditioning manufacturers have responded to the reduction in R410A supplies by introducing a lower GWP alternative, R32, itself a component of R410A, for use in small split and multi-split air conditioning systems. Unlike R410A, however, which is non-toxic and non-fl ammable (class A1), R32 is classifi ed as a class A2L refrigerant, which means it is also non-toxic but is fl ammable in certain circumstances. When handled correctly, it is considered safe to use in smaller DX air conditioning systems, due to the relatively small volumes of refrigerant involved. However, it is not considered suitable for use in VRF/V systems due to the larger charge sizes required, and the fact that refrigerant is distributed throughout a building, often in places where leak detection would be very diffi cult, or the risk of an unidentifi ed leak would be unacceptable.
www.acr-news.com
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