Vented laundry drying having an additional heater and heat exchanger unit

The invention relates to a vented laundry dryer 1, comprising an air inlet duct 3, an air outlet duct 5, a heat recovery system 8-11 for transferring heat from the air outlet duct 5 to the air inlet duct 3, and an additional heater 7, wherein the heat recovery system 8-11 is a heat pump comprising an evaporator 8, a liquefier 9, a condenser 10, and a relaxation unit 11, wherein the liquefier 9 is thermally coupled to the air inlet duct 3, and the evaporator 8 is thermally coupled to the air outlet duct 5, and a relaxation property of the relaxation unit 11 can be adjusted depending on at least one parameter that is connected to an activity of the additional heater 7. A method is used to operate a vented heat dryer 1 comprising an additional heater 7 and a heat pump 8-11 having a relaxation unit 11, wherein the method comprises the following steps: (a) monitoring at least one parameter that is connected to an activity of the additional heater 7; and (b) changing a relaxation property of the relaxation unit 11