personally id put a thermometer on the wall and watch the temperature at the location you propose to install the tv and check if its inside the acceptable operation temperature which should be listed in the manual ( id be suprised if it is) the other thing to check is if theres a magnetic field given off by the rad. Put the heating on and set the TV up on the shelf ( i apreciate you'll need to hold it) and then see if theres any issues with the picture
I know that in older TV's where the picture was tracked magnetically some heating systems effected the guasing ( something to do with the pumps magnetic field being radiated by the system)and caused spurious colours. Obviously on a LCD wont have that issue but its worth check it doest effect something else like a timing component