Laundry machine having a drying function

A combo washer dryer, comprising:

• a cabinet forming an external appearance of the combo washer dryer, the cabinet having a door;
• a tub to provide a space to receive a drum, the tub comprising a hot air outlet that protrudes upward from a rear outer circumference of the tub to collect hot air, a filter provided at the hot air outlet to filter lint from hot air, a hot air inlet located at a front end of the tub to supply the hot air into the tub, wherein the tub forms a condensing device, an outer circumference of tub heat exchanging with external air through natural convection such that air moving to the hot air inlet is condensed at an inner circumference of the condensing device, the tub being provided with a laundry introduction port, opened and closed by the door, through which laundry is introduced into the drum;
• the drum located inside the tub;
• a drying duct located at an upper side of the tub, the drying duct comprising a fan installed at the hot air outlet to collect hot air and a heater to heat the hot air moved by the fan, the drying duct being connected to the hot air inlet and the hot air outlet to heat air in the tub, to supply the hot air into the drum, and at the same time, to collect hot air through the hot air outlet;
• and
• the filter provided in a flow path of hot air passing through the hot air outlet to filter lint from the hot air.