HRR units are designed to meet the hygrothermometric well-being needs and air renewal and quality requirements typical of civil contexts. They are characterised by theuse of a high-efficiency rotary heat recovery unit with low pressure drops (with the possibility of hygroscopic surface treatment). Thanks to the heat recovered the contribution of the air conditioning system is kept to a minimum: in this way the result is greater running economy. Considerable economic savings are also guaranteed by the use of plug fans with electronically controlled motors (up to size 17) or high-efficiency inverter-commanded motors. These are “Plug & Play” units, as they are directly fitted with electronic adjustment and an electrical power panel. The special control software can maximise the use of the unit in energetically favourable conditions.