I have a spare bedroom that has 3 registers. The room never gets used. Although the vents do close, there is some leakage out of them. With winter coming, I was thinking about using magnetic covers to save energy. Is there enough air coming through these vents to make a difference? See link below.
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Also, when I bought my place last year, it did not have AC. I replaced the gas furnace and had central air installed. The two bedrooms are on the upper level. I have a high air return register in the hallway between the bedrooms. I have another air return register on the main level of my home, plus one in the finished basement right by the furnace. Due to high ceilings in the bedrooms upstairs, it takes a lot of heated air to heat the upstairs. Would it be wise, when I start using the furnace, to cover the air return register upstairs until warm weather returns?Thanks!