This blog gets a lot of hits from people searching Google, questioning whether they should cover their cold air return vents.
I just wanted to let you know that it is very unadvisable that you cover these vents. I did for a few years until my Furnace Guy informed me of the details.
Your home needs cold air return vents. The hot air coming from your furnace entering your house must have a source. Unless you have a very sophisticated direct-vent furnace with supply air coming from the outdoors, you need return vents. This keeps the air in your house moving and reduces air pressure from the heater vent air filling your room.
Think of it as a fan in the summer. If you put your fan in your window and open the door, what do you have? Circulating air. What happens if you close all other windows and doors in that room and still run the fan? The fan blades still work, but the circulating air supply is almost entirely choked off, and the cool air no longer vents. It eliminates the fan’s efficiency. Moreover, it makes the fan run and you are still charged for the electricity to run the fan. You are essentially paying for nothing, plus wearing out the fan motor even faster.
A forced-air furnace needs intake air to supply the outtake air. To close off your cold air return vents chokes off the intake air supply. So it not only is costing you more money to do less, it is also making your furnace work harder to run.
My Furnace Guy said that, in a perfect world, every room that has a heater vent should have a cold air return vent. There is a mathematical calculation they use to determine how many return and supply vents a room and house needs. In my old home, I only have TWO small return vents. This is not good. I am trying to fix this, knowing that it is costing me more and making my new furnace wear out sooner. The worst thing I could do is cover my cold air return vents.
So… if you are wondering whether or not you can cover the cold air return vents– no, you can’t.