I purchased a home that currently has a single air return in the hallway. My master bedroom is on the other side of the house and is frequently 3-4 degrees warmer or cooler than the rest of the house. I was debating adding a second return vent in the master bedroom. Would this help my problem? If so, would I need to be concerned about creating a negative pressure? I plan to leave my existing hallway return in place and just add a duct for the bedroom.