Each morning, when I sit at my desk, I give a moment’s thought to the broken copper pipe buried in the concrete slab just below my feet. The guy who lived here before us abandoned that old radiant system in 1970, just 20 years after the crew had hastily installed it. We live in one of those houses built during the Levittown era. William Levitt put up 17,000 houses in a year and a half (that’s 30 houses a day) and I don’t believe he was thinking too much about the details of the floor-heating systems. They went in fast and they were cheap, and both of those things were very good. We now have baseboard radiators.