It used to be we had open fires. But then hot water radiators came in -
much cleaner, and easier to manage.

Nowadays we seem to be moving towards underfloor heating - where
effectively the entire floor is a radiator. Efficient, but slow to respond.

But there was a time when hot air systems were popular, and I think
still are in the USA.

Does anyone know why they went out of fashion? It can't just be because
they made a great place for spiders to hide!

Andy