I think it depends on a bunch of factors - how often you use the fireplace, whether it's a gas or wood burning fireplace, etc. We had an LCD TV over our firepl

I think it depends on a bunch of factors - how often you use the fireplace, whether it's a gas or wood burning fireplace, etc. We had an LCD TV over our fireplace (gas, vented directly outside horizontally) for 12 years. While it just got moved in the past month, it's still going strong.