Canadian House & Home. Here is what they recommend for proper placement:
Treat it Like Art: Your flat-panel TV should be mounted at the same height as you would hang a piece of art of the same size over your fireplace.
If in Doubt, Do a Little Math: Depending on the height of your mantel — or if you don’t have one, the top of the fireplace — hang the TV four to twelve inches above. If your mantel is higher than four feet, then hang the TV no more than six inches above.
Think about a Tilt Mount:: Mounting your TV above your fireplace means it will be higher than normal (ideally, your TV should be at eye level for comfortable viewing) so you may want to consider mounting the TV onto a tilting and panning wall mount so that you don’t have to crane your neck to watch television and can also enjoy the view from anywhere in the room.
Mock It Up First: To help you center the TV to your fireplace and decide on the most pleasing height before you start drilling holes, test out its placement by cutting out a paper rectangle the same size as your unit and tape it to the wall. Evaluate its placement from a sitting position and adjust it accordingly.
Do the Radiant Heat Test: Test out the radiant heat that emits from your fireplace as it could greatly reduce the lifespan of your TV. Assess this by starting a fire and place your hand over the area where your TV will be mounted. If it feels considerably hotter than room temperature, you should consider placing your TV elsewhere in the room.
Check out the full question/answer at Canadian House & Home right here.
Photo: via Ecoustics.com