Why Choose a 21.5x24x1 MERV 13 vs Standard Filter Sizes
The homeowner’s return slot measured 21.5 by 24 inches. He had been loading a 21x24x1 into it for three years. That half-inch gap at the frame edge was routing unfiltered air around the media on every cycle, and none of the filters he installed could perform at their rated efficiency because the seal was never … Read more