Most U.S. steel is made in massive, slow-acting, open-hearth furnaces. Last week U.S. Steel Corp. announced tests of a new type of furnace which makes the same kinds of steel a great deal faster. Open ...

Each type of furnace heats the air a little differently and has a different operating cost. Electric furnaces are often the cheapest of the four to purchase and are easier to install and maintain.

Newly-manufactured indoor residential gas furnaces will have to be at least 95% efficient starting in late 2028 under a new rule issued by the U.S. Department of Energy (DOE). In an effort to save ...