If you are trying to get better air flow of your central heating plus a/c I have a little tip that entirely worked for me, plus it may work for you as well, what I did was close the air vents to my central heating plus a/c that were not in use in spare rooms, etc; By doing this it pushed the air harder through the other air vents in the apartment that were opened. And this in turn created a much better air flow in my home. My central heating plus a/c can heat plus cool my apartment a lot faster plus a lot better by doing this method of closing off air vents in the rooms in my apartment that are not being used. When you have a sizable apartment 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 plus cool in a smaller apartment of course. I have been doing this method now for a few years plus it works real great. I have even been able to save money on my biweekly energy bills because my central heating plus a/c unit does not have to run as long plus as often as it did before I started closing the air vents in the unused rooms of my home! This is a fantastic energy saving tip as well. I guess almost everyone should take notice to what I am saying.