Be sure that your mantel is installed so as to follow the installation instructions in maintaining required distances (”clearances”) from the fireplace to combustible mantels and trim.  Efficient heat output from your fireplace adds value to the homeowner, and does so safely by passing the ANSI and UL standards for combustible temperatures. The allowable is 117°F above room temperature for combustibles. Average room temperature is 70-75°F; therefore a 187-192°F surface temperature can be expected. On a solid surface, 150°F is very hot to the touch (to put this in perspective, water boils at 212°F and the average bath water temperature is 110°F).