How hot is too hot above fireplace

Question

I recently bought a house with a zero clearance fireplace, and had a metal/glass door installed on the front. I suspect the metal door is touching the tiles on the wall above and transferring a lot of heat. When the fireplace is running, I can't hold my hand for more than a few seconds on the bottom of the tiles above the fireplace. However, if I move my hand a few inches up it's just fine. Is this too hot, or expected?

Edit: Here's a picture of the door I had installed. It's made for zero clearance fireplaces. We always have the doors fully open when the fireplace is on. Also, to clarify, this is a gas unit, not wood burning.

Answer 1

i have never seen a zero clearance unit without a door assembly already attached. was this unit open hearth design and then you retrofitted it with the door/glass? or was the door/glass just missing and you replaced it? is it a gas unit or wood burning? the gas units can get pretty toasty right at the top above the trim escutcheon, but it could also be you don't have a tight seal on the new door to the old firebox, thus letting some combustion gas out and giving you too much heat, plus a little carbon monoxide for good measure. if its a wood unit, you don't need to worry too much other than the heat degrading the tile mortar or adhesive. either way, it should never get above 45 deg c, as that's the limit for temps on combustibles (tile no, but wood behind tile, yes) around a zero clearance unit