Potenze frigorifere nominali da 4 kW a 68 kW. The new Cygnus and HCygnus units are air-cooled chillers and heat pumps with R407C refrigerant, rotary or hermetic scroll compressors, plate evaporators, circulator or centrifugal pump, and tank. A particularly important role is reserved for the electronic controller, which automatically regulates fan speed in accordance with the instantaneous load of the installation; this means that when operating conditions are not excessively demanding fan speed can be reduced, providing signifi cant benefi ts in terms of power consumption and acoustic comfort - a fundamental requirement in a large number of different installation contexts. The new defrost logic developed by MTA makes it possible to de-ice the condensing coils while minimising the duration of the defrost cycles and guaranteeing major energy savings. Finally, the use of R407C refrigerant, the reduced quantities of refrigerant in the unit's circuits, and complete segregation between refrigerant circuits and the interior spaces where people live and work, mean that the new Cygnus/HCygnus series of units are both totally safe and ensure the lowest possible environmental impact.