Joful is quite correct... Before stoves became commonplace in the early/mid 1800s the expectation was only to heat the room in use, and even then you were diong well if you didnt have to wear a hat indoors. During the day typically the kitchen was the only room warm, and overnight all the fires were allowed to die and you would pile up under a lot of blankets and maybe a bedwarmer if you could afford the extra fuel. That was the reason for 4 post beds - they where fully draped in to hold in body heat. It was typical to wake up in the morning to frozen water pitchers indoors. Also, the purpose of central chimneys was all about using the masonry to keep the heat IN the building, nothing to do with sweeping. This is why we see central chimneys in new England, and exterior chimneys in the south.