The best way to improve the efficiency of your return air vents is to check your furnace filter. If the filter is too old, it is probably reducing the efficiency of your return vents, and you should change it. Furnace filters should be changed every six months anyway.
How Do They Work?
A return vent sucks in air and delivers it to the heating/air-conditioning system to be treated. The treated air is then forced out of the air vents into the rooms of the house, starting the cycle over again.
Using Proper Vents
Another good way to improve the efficiency of your return is to make sure the grills aren't blocking the airflow. Also, keep in mind that the size of the return vent depends upon the size of both the room and your ducts. Some large spaces might require multiple vents, and some small rooms that don't have vents might benefit from having them. In general, you want your HVAC system to have about as much return capacity as supply capacity.
Sometimes vents get blocked by rugs, couches, or the like. Try to avoid doing this to your vents as it will reduce their efficiency. Some systems have two sets of return vents, one up high for warm air and one low to the floor for cool air. The low vents stay closed in the summer and the high vents stay closed in the winter.
Shutting the Vents
A popular misconception about vents is that by shutting some you can improve the efficiency of others. By closing vents, however, you raise the pressure in the ducts, causing more harm than good.
The last step in ensuring the efficiency of your return vents is to clean them on a regular basis. You can use your vacuum cleaner. Just remove the grilles and vacuum out any dust you can reach with your attachment. This is sufficient most of the time, but every once in a while you should call in professionals for a more thorough cleaning.
Your return air vent plays a vital role in the cooling and heating of your home. You'll breathe a little easier with these efficiency and placement tips!