Praefurnium

• The Praefurnium was the Furnace in the Roman Baths.
•  The Furnace was kept burning by Slaves, usually using a supply of wood.

Roman Baths

• The Caldarium was above the Furnace making it the hottest room.
• Hot air then circulated under the Hypocausts and up the walls of the Tepidarium.
• The hot air then continued into the Frigidarium, which was the coolest room because it was the farthest away from the Furnace.