What is a Praefurnium?

A praefurnium is a type of furnace used in ancient Roman baths, primarily for heating water. It was typically located in the hypocaust system, which allowed hot air to circulate beneath the floors and through the walls of the bathing areas. The praefurnium was essential for maintaining the desired temperatures in the caldarium (hot room) and other bathing facilities, contributing to the overall luxury and comfort of Roman bathing practices.