It's one thing to place your houseplants in direct sunlight, but you won't do them a favor by putting them near a direct heat source (radiator, duct, oven). Doing so will dehydrate your beloved plant quickly; even if you water it diligently, the leaves will dry out. The same goes for air conditioners and vents. Plants can't handle extreme temperatures, so consider where you place them. If you happen to live in a professional kitchen, or some sort of sweatbox factory, at the very least make sure to insulate the plant by placing a thick board between the pot and the direct heat source.