Q&A: Is it a good idea to cover A/C vents in spare rooms?
Q. My husband has put magnetic covers over the air conditioner vents in the spare bedrooms. The bedrooms are not in use. He claims more air will come into our bedroom. The air is still blowing against the covers in the spare rooms. I think it is a waste and we still are not getting cool air in our bedroom. Who is right? -Mrs. M.C., Edison, N.J.
A. Your central air conditioning system not only supplies air to your home but it is designed to recirculate back to the furnace some of that same air via a “return air duct”. The amount of supply /return air is a engineered relationship. If the supply ducts are blocked then the system blower fan motor has to work harder to both supply and return air. This shortens the life of the motor and increases the cost of the cooling operation.
Often, when an area isn’t being properly cooled then the ducting to that area is replaced with a supply line that is of a greater diameter. Thus, allowing more air to flow to that area with less resistance. Ducting to other areas may be reduced in size to compensate. Sometimes not. In any event, it is a good idea to have all the supply registers in your home tested for pressure, volume and temperature. By doing this you may discover that something simple has gone wrong that can be easily repaired. For example: the supply line to your bedroom might have rusted out in one or two spot. Or maybe the duct has opened at a joint. Contact a heating contractor who can make such a test for you. It may also be time to conduct a thorough duct cleaning.