VRF Systems and Failures: The Role of the System Designer

Session 3, Paper 1, CIBSE ASHRAE Technical Symposium, Dublin, Ireland, 3-4 April 2014

VRF heating and cooling systems are deceptively simple, almost “plug and play” and increasingly popular; they currently represent at least 25% of new systems. Superficially similar to water based systems; individual fan coil units can heat and/or cool and the systems are relatively energy efficient. Design of the systems requires the skills of both refrigeration and building services engineers but manufacturers appear to have almost eliminated the need for any design by a building services engineer by providing simple step by step guides and software. Or have they?

Like all air conditioning systems, VRF systems fail from time to time, or fail to provide the comfort conditions the users expect. However the reasons why VRF systems fail are often different to failures in water based systems and can be due to a lack of understanding by, or by the absence of, a building services engineer in the design process. The paper is based on experience from 12 VRF systems that have failed to operate satisfactorily or reliably, suffered excessive complaints from occupants and become the subject of or at risk of becoming disputes. It provides examples of problems in real life, reviews the role of the building services engineer or system designer and includes advice for designers to help prevent common problems and failures.