A. Frank Vigil, of Advanced Energy in Raleigh, N.C., responds: You are correct in assuming that a pressure imbalance is causing the carpet to filter particulates out of the air. However, simply adding additional return air is not likely to correct the situation.
In dealing with carpet filtration, the most effective strategy is to remove the source of the soiling. A number of things can cause carpet stains, from simple dirt and dust to more complex sources such as soot from candles or improperly functioning combustion appliances. Get rid of the source and you’ll get rid of the problem.
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