FLS High efficiency (>80%) heat recovery unit. The unit is made with aluminium profiles with thermal break and sandwich panel 42 mm thick high density thermal and acoustic insulation of mineral wool. The base-frame is made by high thickness galvanised steel, specially designed for installation on roof. Counter-flow aluminium heat exchanger, air filters are soft bag in class F7(optional F9). The inlet and exhaust fans are type plug-in fans with backward blades, directly coupled to a a brushless DC electronic motor. FLR is available with an integrated water coil for heating and/or cooling.