Dimensions and duct outlets Figure 1. Dimensions and duct outlets Inner diameter of the female collar ∅ 250 mm (R and L models). Duct outlets, R model 1 Extract air from the apartment to the unit 2 Supply air from the unit to the apartment 3 Outdoor air to the unit 4 Exhaust air flowing outdoors from the unit 5 Liquid radiator output (VKL model) 6 Liquid radiator input (VKL model) 7 - 8 -