A heat diverter attached to an electric dryer captures waste heat, but can also create moisture and air-quality problems. Get better results by managing the loads and keeping dryer lint under control.
Venting the dryer outside in cold weather wastes a lot of heat. To make the dyer more efficient, you can buy an inexpensive heat diverter and install it in the exhaust duct of electric dryers only (not gas dryers).You'll save about 50¢ worth of heat per load in the winter.
But we don't recommend it for two reasons. First, you'll be pumping a heavy dose of moisture into your home with each load. In cold weather, that moisture can condense where you don't want it—on windows, inside walls, in the attic—and can cause mold and rot. And second, you'll blow fine particles of lint through the filter into your household air. Here are better ways to save energy when you're drying clothes: