You seem to see it frequently in photos on Houzz. Would be curious to hear if anyone has any tips on wood burning vs. gas with television placement. It may have a lot to do with the size of your firebox, distance, mantle, etc.

It's not a hazard so much as it will ruin the screen of your television.

http://www.geeksugar.com/Dangers-Mounting-Flat-Panel-Above-Your-Fireplace-2950374

Thank you jeq87 for the very informative link which one should read if contemplating putting a TV over a fireplace.

As long as your fireplace draws properly and is not throwing a lot of heat up the fireplace wall AND you place the TV at least 16" above the opening you should be fine. If you have enough heat to ruin the screen that far above your fireplace, there is something wrong with your fireplace.

We've had a 42" plasma mounted on the brick above our wood burning fireplace for over 2 years now with no problem whatsoever. I watch it almost every night since the hearth room is my hangout spot. There is approximately 3' and a wood mantle between the bottom of the TV and the top of the fireplace opening. No problems so far.

Put thermometer where you plan to mount the tv. Turn on the fireplace for a couple of hours to see how hot it gets. Since no two houses are the same and check your tv manual for operating temps. Remember the hotter it is the short time the tv will last.

Better get the checking done by a expert .

The article linked above says mounting a TV over your fireplace can shorten the life of your television IF you're not careful. It then goes on to tell you how to do it/get it done properly.