Many people do not realize how the improper use of air supply grills can effect your system in an adverse way. Each air supply grill is designed to circulate specific amounts of air throughout your home. You should never close your grills even if you don’t use a particular room or area of the house, doing so will not save you any money and you could damage your cooling system. Your grills should be wide open at all times. If you would like to have certain areas of your home split into zones you should invest in a Zoning System that will allow you close off a certain area of your home using electronically installed dampers in the ducting system to restrict air flow to the ducts that are not in use.