Having your HVAC system’s airflow balanced means heating and cooling airflow to every room into the house is consistent with the size of the room and balanced with the amount of air removed from of the room by the return airflow. This results in a condition of neutral air balance, considered optimum for effective and efficient heating. When airflow is out of balance, a range of performance and energy-efficiency shortfalls will affect your HVAC system, household comfort and indoor air quality.
- When air volume conveyed to rooms in supply ducts exceeds the amount removed by the returns, over-pressurization results. In a pressurized state, the temperature comfort zone is hard to maintain. Conditioned air is pushed out of the house through structural cracks and gaps; humid air infiltrating wall voids and the attic may trigger mold growth. Temperatures and airflow will vary by location.
- When air volume removed by returns ductwork exceeds the amount delivered by supply ducts, depressurization happens. Unconditioned cold or hot outdoor air is sucked into the home to equalize the pressure differential. HVAC systems work overtime to compensate for the effect, and operating costs rise. Contaminated air from the crawl space, attic or wall voids may be continuously pulled into living spaces.
Getting airflow balanced means an HVAC professional will inspect the ducts for defects like these:
- Improper layout. Duct layout must incorporate correct duct diameter for the air volume, length of spans, and number of bends and restrictions. All these factors influence air balance.
- Duct leaks. Supply duct leakage generally depressurizes rooms, while return duct leakage causes room balance to tip toward the positive. An HVAC technician can pressure-test ducts to pinpoint leaks and offer duct-sealing options to restore balanced flow.
- Insufficient return air. In homes with a central common return duct grille, airflow from individual rooms may be obstructed if the room doors are closed. Air pass-through vents should be installed in doors or jumper ducts routed through ceilings to convey air back to the return grille.
For more information about having your airflow balanced for improved system performance in your Fresno area home, please contact us at Donald P. Dick Air Conditioning.
Our goal is to help educate our customers in the greater Fresno, California area about energy and home comfort issues (specific to HVAC systems). For more information about system airflow and other HVAC topics, download our free Home Comfort Resource guide.
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