3. Installing the wrong filter
Make sure you have the right filter installed.† Most HVAC systems were designed to use one of those cheap fiberglass filters to clean the air.† Unfortunately, they donít do a very good job at it, so many people go to their local hardware or big-box store and buy a super-duper high efficiency pleated paper filter GUARANTEED to keep their air cleaner.† It might actually keep the air cleaner, but it also cuts down on the air flow, making the whole system less efficient.† They can make the cooling coils freeze, creating even bigger problems.† If you really need a good filter, first seal the ducts to keep the air in and the nasty stuff out, then get a 6 inch thick pleated filter which fits into a special cabinet which your HVAC contractor can install for you. They do a good job filtering the air and donít cause the same problems with the air flow.
4. Not enough return ducts
The last thing Iím going to talk about is return ducts. Lots of HVAC systems are installed with a single, large return somewhere in the middle of the house.† Each room has its own supply, but the air is supposed to, sort of magically, slide under the door and get back to the big return duct to be cooled again.† The problem is that the space under the door usually isnít big enough, so the air doesnít flow through the whole house well enough to keep things evenly cooled.† Some rooms are hot, some are cold, and none are just right.† Consider having an HVAC contractor add some extra return ducts in bedrooms and other rooms with doors (except for bathrooms) to give you better air flow and increased comfort.
Notice that I havenít said anything about equipment efficiency.† Thatís what the manufacturers and installers talk about, because they can make a lot of money selling you fancy, expensive air conditioners that are super efficient.† The problem is, if you put one of those on a system that is otherwise pretty crappy, you have wasted most of the super-duper efficiency you paid for. Take care of the more boring, tedious, and important things like these first, before you install new equipment.† Youíll be much happier, and more comfortable.† Then when you want to put in that super duper equipment, youíll have a really good HVAC system.