TV over fireplace - ran our own heat test - good results
Bottom line: our test measuring temperature of the heat above the fireplace using thermometers attached to the wall while having an active fire indicated heat doesn't get too hot. YAY!
Had to wait for some cold weather before we could run our fireplace test. Here in Houston, cold doesn't come along too often. Today, Saturday, it was 50 degrees this morning and I'm antzy to buy a TV on Black Friday to make some serious progress on this project so we made a fire in our fireplace. Over a period of 4 hours, we used 6 healthy sized logs. I placed little thermometers that I bought at the corner hardware store ($5 each) that have a sticky back about 1 foot above the fireplace opening and also 18 inches above the fire place opening. The Fire was pretty strong a good part of the time. Wood was fairly dry, we had kept it under cover for a couple of years.
Anyway, good news, actually GREAT news is that none of the 4 thermometers went over 90 degrees. There is no mantel on this fireplace at this time, just a brick surround because we have done some partial demolition in preparation for our major remodel. 3 of the 4 thermometers never reached a temperature greater than 85 degrees. The fourth one hovered just under 90. We could feel some nice little heat in the room and apparently quite a bit of heat must have gone up the chimney because it didn't bother the sheet rock above the fireplace.
The thermometers were kind of cheap so I used 4 and also bought a couple different brands and also ran a little test with them on the hot brick making sure they could reach higher temperatures and they performed quite well IMO.
Our house was built in 1939. It's pier and beam construction. There was a fire in the house apparently as a result of the fireplace at one time (before our time) because we noticed some charred wood when doing some work fixing a water leak a couple years ago. So not sure exactly when the fireplace was rebuilt but we had it inspected and it passed. (Inspection included a camera up the chimney.)
We did have some smoke in the house today. It was okay until 3 or so hours passed and smoke level got a bit uncomfortable. We're looking into that but we don't plan to have fires like we did today that often so we may overlook the problem for now. A fireplace guy who also does marble is supposed to come out on Monday.
Now that we have the heat issue resolved, next question is how high to place TV. We're investigating adding a "lentil" which means we could gain maybe six inches i.e. the TV could be mounted 6 inches lower and we think we would still have a nice opening for a fireplace. But after today, the fire was so nice, we're not sure sure we want to reduce the vertical height of the opening. Still thinking.
If fireplace guy agrees, given the fact that our firebox is pretty level on the floor, we think we could have the bottom of the TV at around 46 inches or so from the floor - not too high ...more to find out. (need to confirm code)
disclaimer: I doubt that the data from our fireplace heat test would apply unequivocably to other fireplaces. There are probably a lot of variations. I think you've got to run your own test but my point here is that it was fairly easy to find out for ourselves. Every contractor we talked to had a different answer and also, I've noticed postings on the web vary quite a bit. You gotta do your own research.
I'll post as we get further along on our project. Hope to have some pictures along the way but our camera is usually at my husbands office - gotta do something about that.
We're going at a snail's pace but at least we're moving finally. Home theater guy was out a couple of days ago. Hopefully we'll have that put in soon.