Pianos are Sensitive!: Pianos are sensitive to changes in temperature and humidity. Where you place the piano is critical to the stability and longevity of the instrument.
Pianos Don't Like Change: As far as possible, the piano should be in a place with the least amount of change in the atmosphere, out of direct sunlight. That means as far from a heat source, vent, or open window or door.
Sunlight: West facing windows allow a lot of heat in, which is not good for a piano. Some brief sunlight from a southern sky or eastern window is okay. Wood colored finishes are especially prone to bleaching in sunlight, even if it is indirect. I strongly advise getting UV film on your windows to protect the finish of your piano and furniture.
Tags: atmosphere, new piano, piano placement, UV Film