Problem With The Thermostat

This winter we have been having problem with our heaters on the first floor. Sometimes the rooms are freezing cold, while the thermostat keeps telling me its more than 70F! At first, I thought something must be wrong with my furnace, but the second floor (different zone) is perfectly fine. Then I thought it could be problem with the first floor thermostat, since it reads the temperature so high, higher than the temp I set, so the heaters just won't start. We even thought about calling some plumber or someone else to service the furnace and check on that thermostat. But then it works just fine sometimes. It was really frustrating, we had to wrap up in blankets to watch TV. Then last Sat. suddenly a light went on in my head! It's the new TV! We bought this big LCD TV several months ago, and we put it where our old TV was, which is right under the thermostat. But this new TV generate more heat, so behind it is another zone! The thermostat read that temperature, and thinks the whole first floor is that warm. Finally we found the reason. But how should we fix it? That's the only place in our small living room where we can put the TV, and we really don't want to call in a electrician to move the thermostat. Then DH just popped up a great idea (this has never happened before), we can put a shelf on the wall, above the TV, to block the heat from reaching the thermostat. What an excellent idea! He has no idea about house and decorations at all, he didn't know those shelves called floating shelf, but I think this is the best suggestion he has given me. So, now I am on a shelf hunt, try to find the perfect size and color. There are so many out there, and so many ways to arrange them. I like the color in this first picture, it matches our other furniture in that room, but I will probably arrange them like the other two pictures. They look more interesting.