"My HVAC Is Just Below Our TV Room And When It Comes On It Gets Loud Enough That We Have To Turn Up The TV Volume."
A noisy register from high volumes of air going through them can be be very annoying. All air vents, both supply registers and return grilles make some noise when the system fan is running; this is normal. Some systems are louder than others but some systems are much louder like the quote above from a homeowner having an online discussion trying to find a solution to their problem.
The speed of the air blowing through the supply registers and the air being drawn into the return grille affects an air conditioner's performance. If the air speed is too high, it will be noisy and uncomfortable, and the return grille filter effectiveness will be reduced. The speed through the grilles depends on the size of the air conditioner (a larger unit has more air flow and higher air speed) and the area of the grille (a smaller grille causes higher air speed).
With a properly sized air conditioner, it is easier to have sufficient supply and return grille area to keep the air speed low and the noise at a minimum. Common complaints about oversized air conditioners are that they blast frigid air and that they are noisy. A properly sized air conditioner, with proper ductwork and grilles, will provide longer cycles, more consistent temperatures, and better mixing of the house air.
So, obviously, when you properly plan the replacement of your A/C or Furnace, installing the right size HVAC system, you avoid this situation. At that time, we can evaluate your house to see if there are enough return air including return vents in every room. By the way, that may help your current system operate quieter. By adding more return air, the pressure reduces, the system doesn't have to works as hard and it quiets down.