Outdoor unit for a heat pump comprising a refrigerant circuit, the outdoor unit comprising: a casing, a fan accommodated in the casing, the fan having fan blades rotatable about an axis of rotation, a molded grille covering the fan blades, the grille (100; 1000) being divided into a first area and a second area, the first area being defined so that the minimum distance between the fan blades and an outer surface (101; 1101) of the grille (100; 1100) is not more than a first threshold, and the second area being defined so that the minimum distance between the fan blades and the outer surface (101; 1101) of the grille (100; 1100) is larger than the first threshold, wherein openings (102; 1102) are formed in the first and second areas of the grille (100; 1100), a smallest dimension of each of the openings (102; 1102) in the first area perpendicular to the axis of rotation of the fan blades is not more than a second threshold and a smallest dimension of at least some of the openings in the second area perpendicular to the axis of rotation of the fan blades is larger than the second threshold, wherein the openings are formed by first horizontal ribs and second vertical ribs extending perpendicular to the first horizontal ribs, wherein the second vertical ribs comprise smaller ribs and larger ribs, the smaller ribs being smaller in depth in the direction parallel to the axis of rotation of the fan blades than the larger ribs, wherein a front edge of the smaller ribs is displaced towards the back with respect to the front edges of the larger ribs relative to the front edge of the first horizontal ribs. a casing, a fan accommodated in the casing, the fan having fan blades rotatable about an axis of rotation, a molded grille covering the fan blades, the grille (100; 1000) being divided into a first area and a second area, the first area being defined so that the minimum distance between the fan blades and an outer surface (101; 1101) of the grille (100; 1100) is not more than a first threshold, and the second area being defined so that the minimum distance between the fan blades and the outer surface (101; 1101) of the grille (100; 1100) is larger than the first threshold, wherein openings (102; 1102) are formed in the first and second areas of the grille (100; 1100), a smallest dimension of each of the openings (102; 1102) in the first area perpendicular to the axis of rotation of the fan blades is not more than a second threshold and a smallest dimension of at least some of the openings in the second area perpendicular to the axis of rotation of the fan blades is larger than the second threshold, the first area being defined so that the minimum distance between the fan blades and an outer surface (101; 1101) of the grille (100; 1100) is not more than a first threshold, and the second area being defined so that the minimum distance between the fan blades and the outer surface (101; 1101) of the grille (100; 1100) is larger than the first threshold, wherein openings (102; 1102) are formed in the first and second areas of the grille (100; 1100), a smallest dimension of each of the openings (102; 1102) in the first area perpendicular to the axis of rotation of the fan blades is not more than a second threshold and a smallest dimension of at least some of the openings in the second area perpendicular to the axis of rotation of the fan blades is larger than the second threshold, wherein the openings are formed by first horizontal ribs and second vertical ribs extending perpendicular to the first horizontal ribs, wherein the second vertical ribs comprise smaller ribs and larger ribs, the smaller ribs being smaller in depth in the direction parallel to the axis of rotation of the fan blades than the larger ribs, wherein a front edge of the smaller ribs is displaced towards the back with respect to the front edges of the larger ribs relative to the front edge of the first horizontal ribs.