How did the people in the middle ages heat their homes?

How did Romans heat their homes?Rich Romans liked to be warm and cosy. They had central heating at home, in villas and in public baths. The heating system was kept going by slaves, who kept a fire blazing in a furnace to heat warm air. The warm air moved around the building through spaces under the floors and between the walls. The underfloor space was made by raising the floor on top of piles of tile or stone. The Roman heating system was called a hypocaust.