Mitsubishi Electric has launched the City Multi YLM VRF (Variable Refrigerant Flow) range of air conditioners.

The system includes a flat tube aluminium micro-channel heat exchanger which the company describes as “a world first” and believes is a pivotal step change in providing more effective and efficient heat transfer. Protected with a special zinc coating, the aluminium heat exchanger is said to be ideal for the UK’s temperate climate.

Available from January, YLM has been designed for seasonal efficiency from day one and in addition to the use of aluminium, includes selectable increased and automated evaporating temperature control, optimised design of refrigerant circuit and components, and the ability to provide heat during defrost.

The use of aluminium has called for a complete redesign of refrigerant distribution and heat exchange which, along with several other innovative design changes ensures optimum performance in real UK applications. Together the improvements offer up to 27 per cent annual energy saving compared to the previous equivalent City Multi systems, the company says.

Units are available to deliver from 22 - 101kW capacity to a building in both heat pump and heat recovery variants, with up to 50 indoor units connectable to the largest model. The smallest unit in the range, the PUHY-EP200YLM-A model is just 740 x 920 x 1710mm in size, making it transportable in a standard building lift.

Mitsubishi Electric says the “world first” use of flat tube aluminium micro-channel heat exchanger in a VRF system not only delivers greater efficiency, it also means that the YLM delivers 26 per cent more contact with the refrigerant and 30 per cent more piping per area. At the same time, it reduces both weight and footprint and offers 10 per cent less system refrigerant volume than previous models.

This offers designers a much more flexible system, especially where EN378 restrictions are in place, such as hotels, and offers improved efficiency and performance and higher heat transfer.

The design changes include a new compressor optimised specifically to maximise efficiency during part load, therefore offering high seasonal efficiencies and helping to reduce standby power consumption by 50 per cent by using an induction-heated compressor.

The YLM range also includes a redesigned bellmouth grille to aid airflow, reduce static pressure and lower the energy consumption of the new DC fan motor.

Air conditioning product manager Mark Grayston said: “Two of the most important aspects that YLM addresses are the defrost cycle and occupant comfort levels.”