If you are trying to get better air flow of your central heating and air conditioning system I have a little tip that actually worked for me, and it may work for you as well.
What I did was close the air vents to my central heating and air conditioning system that were not in use in spare rooms, etc.
By doing this it pushed the air harder through the other air vents in the house that were opened. And this in turn created a much better air flow in my home. My central heating and air conditioning system can heat and cool my home a lot faster and a lot better by doing this method of closing off air vents in the rooms in my house that are not being used. When you have a big house like I do, you will most likely have these kind of rooms unless you have a super large family. Even in smaller homes this method should work the same, if not better because there are less spaces to heat and cool in a smaller home of course. I have been doing this method now for a few years and it works real great. I have even been able to save money on my monthly energy bills because my central heating and air conditioning system unit does not have to run as long and as often as it did before I started closing the air vents in the unused rooms of my home. This is a great energy saving tip as well. I think everyone should take notice to what I am saying.