Return air grilles, keep them unrestricted!
Return air grilles are a critical portion of the typical HVAC system. Once warm air is distributed throughout the structure via the supply registers, the warm air which has transferred it's heat energy to the room proceeds to return to the furnace by way the return air grilles. The cooler air is heated up again and then returned again through the return air grilles. To do their job effectively the return air grilles must never be restricted. That means that the design chosen for the faceplate must be reasonably open and allow for free air flow. Furthermore, never put a damper on return air grilles. If the damper was ever closed then damage to the system could ensue. Return air grilles on the wall or ceiling are typically not too problematic. However, because of the large size, it pays to consult with an expert before getting return air grilles on the floor. The larger the dimensions the more likely there will be deformation and breakage, so it is important to evaluate whether or not the return air grilles will require extra structural support.