Finding the best heat pump tumble dryer under 400 doesn't mean settling for less. These machines use recycled hot air to dry clothes gently. They cost far less to run than vented or condenser models.
Energy efficiency is the real selling point. Most carry an A++ or A+++ rating meaning lower electricity bills over time. Brands like Beko, Hoover and Bosch all offer solid options at this price.
Expect capacities between 7kg and 9kg. Sensor drying stops the cycle automatically preventing shrinkage. Heat pump models are slower but kinder to fabrics and your wallet long term.