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Furnace Problems Due to Restrictive Airflow

Most furnaces need two types of air flow. First, they need incoming air from supply vents to ignite their fuel source. Second, they need a steady airflow out into the ductwork of the house so the heat can be passed through the home. If airflow is restricted on either end, furnace efficiency will be impaired. Any blockages, clogs or similar issues should be quickly resolved to remove several serious problems.
  1. Combustion Issues

    • A furnace needs a certain amount of airflow to combust its fuel properly. This is why every furnace is sized for a particular vent size. When the furnace cannot get enough air to properly burn its fuel, it will produce low flames and only small amounts of heat, working much harder to produce the same temperature change. If airflow is restricted enough, the primary burners may not be able to work at all.

    Poor Heating Quality

    • When a furnace cannot get enough air to properly produce heat, or when air filters become overused and clogged, air will not be able to flow throughout the house as quickly as it should. Heat is soon lost through ductwork, crawlspaces and the furnace itself. As a result, heating quality is low and the far rooms of the house are especially difficult to heat.

    Dirt and Mold

    • When air flow is low, this is a sign of clogs or blockages in the system. These problems can often provide friendly environments for dirt to build up and mold to develop. Mold in air ducts can spread spores throughout a house and cause not only allergy issues but also damage to a variety of materials where the mold can establish a colony. Unrestricted airflow can also help keep ductwork free of problems like this by ensuring dirt does not build up inside the ducts.


    • Combustion issues mean that more fuel must be used to produce warmth, poor heating quality means that the furnace must run longer than usual to heat the house and mold must be removed...all these things can quickly add up to high costs. Restricted airflow in a furnace, although a minor problem, leads to large expenses over long periods of time.