What is the impact of not having a return air duct for a furnace?

The absence of a return air duct for a furnace can significantly influence heating efficiency. When a return air duct is missing, the system struggles to draw in sufficient air to replace the heated air being pushed out by the furnace. This imbalance not only leads to inadequate heating in certain areas of a building but also forces the furnace to work harder to maintain the desired temperature. This overexertion can result in higher operational costs and premature wear on the furnace and its components.

Additionally, without a proper return path for air, the overall system is less effective at circulating and mixing the warm air throughout the space. Consequently, areas may experience cold spots, leading to an inconsistent environment that fails to meet heating demands efficiently. Thus, the lack of a return air duct directly impacts the capability of the heating system to function effectively, making this choice accurate regarding the consequences of such a design flaw.