It ruins some TVs and never touches others. The difference is your specific fireplace, and there is exactly one way to find out which one you have.
Every article online hedges on this and then tells you to test it without telling you how. So here is the actual test. It takes an hour and costs about $8.
Max operating temperature most TVs are rated for
What a wood fireplace can hit on the wall above the mantel
LG rates its OLED panels for 32°F to 104°F. Most other brands land in the same range. If your wall stays under that, you are fine. If it does not, you are cooking your TV every time you light a fire. Nothing else about this question matters until you know which side of that line your fireplace falls on.
Plenty of setups are completely fine, especially with a deep mantel or an electric unit. Blanket warnings are lazy. Your house is not every house.
A mantel is the single biggest thing protecting your TV. It pushes rising heat out into the room instead of straight up the wall. But a shallow mantel deflects less, and a TV mounted low still sits in the hot zone. It helps a lot. It does not guarantee anything.
Wood gets hotter faster, but a gas fireplace running for three hours on a cold night can push wall temperatures past a TV's rated limit too. Run time matters as much as fuel.
Your hand cannot tell 95°F from 115°F. That 20 degree gap is the entire question. This is why the thermometer is not optional.
Damage from operating a TV outside its rated temperature range is typically excluded from manufacturer warranties. So the worst case is not just a dead TV, it is a dead TV you pay to replace yourself.
Honestly, the complaint we hear most often is not a fried panel. It is neck strain. A TV over a mantel usually sits higher than it should, and people feel that every night. Worth deciding on before you drill.
Everything above is general. This is the part that answers it for your house.
Any basic indoor thermometer works. About $8 at a hardware store. A digital one with a max-reading memory is even better.
Not on the mantel. The bottom edge of the screen is the hottest point the TV will actually experience, so that is the number that matters.
Five minutes tells you nothing. The wall needs time to heat up and level off. An hour on the highest setting is your realistic worst case.
Do not wait until it cools. Read it hot, and write the number down.
A bad number does not mean you are stuck with a TV on the wrong wall. It means something has to change first.
A deflector redirects rising heat out into the room instead of up the wall. Often the cheapest fix.
More overhang means more deflection. Even a few inches changes the reading noticeably.
Parks the TV high and out of the way, then drops it to eye level when you watch. Solves heat and neck strain together.
Sometimes the honest answer. We will tell you if that is the call rather than sell you a mount that cooks your TV.
We bring the thermometer to your free quote, run the test, and give you the number before you commit to anything.
Book a free quote