Whilst we take such things as fireplaces and radiators as all commonplace in our homes this was not what our ancestors had. Before the arrival of the Romans on the scene homes were heated in a very direct fashion, namely there was a fire pit dug in the middle of the room and hole was made in the thatch to allow the smoke to escape. Whilst this was effective it was also very smelly and hazardous to the lungs. It was no surprise then that when the Romans suggested a different approach it was soon taken up by the Ancient British leadership. Basically they brought in underfloor heating.
Roman technology was very advanced both militarily and socially. They had benefited from the experience and knowledge of the Greeks, who had in turn got their ideas from the Middle Eastern civilizations like Persia and Babylon. The Roman idea was underfloor heating. There were two ways of doing this. One way was to dig large channels through the earth and line them with stone. Stone or marble mosaics were then placed on top. The other option was to have the floors supported by stone columns. This allowed warm air from a constantly fed furnace to circulate underneath warming the floor and the room.
It was a highly efficient system that created a strong and more subtle warmth to a room and there was no inconvenience of smoke getting into the lungs. It was also a sign of great wealth and privilege to have one. It still needed to be maintained just like our modern boilers today. A Boiler Service Gloucester based firm like https://www.hprservicesltd.com/gloucester-boilers/boiler-service-gloucester/ can help with all your modern day heating needs.