Ventless clothes dryers work differently since they cannot vent the hot air. The two types of ventless dryers are condensation dryers and heat pump dryers. Condensation dryers heat the air the same as a regular dryer, but use a heat exchanger. The air is cooled and the water goes down a drain. A heat pump dryer works similarly but passes the air a heat pump. The water either goes down the drain or into a collection tank.