Furnaces today aren’t quite the same as they were just four years ago. For one thing, furnaces are getting smaller, according to Energy and building science blogger Allison Bailes.
“Manufacturers, in their drive to improve efficiency of their equipment, are making furnace cabinets smaller while at the same time increasing air flow,” Bailes writes, using information from a recent presentation by fellow building science expert and enthusiast David Hill.
As HVAC components become more compact, air flow properties also differ. Bailes uses oval ducts as an example.
“Oval ducts are used sometimes because they fit inside wall cavities,” he writes. “Because they have the rounded corners instead of square, a lot of installers assume oval ducts are equivalent to round duct.”