In Ancient Korea they used underfloor heating.

Show me more I want to see this in action

As did the Romans.

Great story. I want an ondol now!! But i would have the floor way to hot all the time

I was literally thinking about underfloor heating and then I opened x and my feed was here…. spooky action

Most modern apartments have floor heating too. It's traditional.

Sounds like a pretty good way to burn your house down

It's pronounced on dole spelled ondol just for future reference