There are quite a few (literally) ins and outs to a central HVAC dusting system. Importantly, many people don't realize that some of the air registers mounted on their walls are actually returns. Air returns are basically where the air is sucked back into your duct system, where it is then circulated to the furnace or heat transfer device (depending on the set up of your system). The air returns are extremely important junctions in a typical central HVAC system.
19 January 2018