The return air flow on a furnace refers to the process where indoor air is drawn back into the heating and cooling system.
Understanding Return Air Flow
In a forced-air HVAC system, the furnace or air handler operates by circulating air throughout your home to maintain a comfortable temperature. This process involves two main air pathways: the supply air and the return air.
According to the provided reference, "Return air, meanwhile, is removed from rooms and flows back through return ductwork to the indoor air handler to be filtered, then heated or cooled again by the furnace or AC." This air, having circulated through the occupied spaces, carries airborne particles and has either been heated or cooled.
The Cycle of Conditioned Air
The return air flow is a critical part of the continuous cycle that ensures your home remains comfortable. Here's a simplified look at the journey of the air:
- Collection: Air is pulled from various rooms in your home through return air grilles, often located on walls or floors.
- Pathway: This air travels through a network of return air ductwork.
- Filtration: Before reaching the furnace or air conditioning coil, the return air passes through an air filter. This filter captures dust, pollen, pet dander, and other particles, protecting the equipment and improving indoor air quality.
- Conditioning: The filtered air enters the indoor air handler where the furnace heats it in winter or the AC coil cools it in summer.
- Distribution: The now-conditioned air is pushed through separate supply ductwork and exits through supply vents (registers) back into the rooms, completing the loop.
Why Return Air is Important
Proper return air flow is essential for several reasons:
- Completes the Circuit: It provides the necessary airflow for the furnace or AC to operate efficiently and effectively, ensuring that conditioned air reaches all parts of the house.
- Enables Filtration: All the air circulating through the system passes through the filter via the return ductwork, cleaning the air you breathe.
- Maintains Pressure Balance: A balanced return and supply system helps prevent issues like pressure differences between rooms, which can cause drafts or make doors hard to open/close.
- Equipment Health: Adequate return air prevents the furnace or AC from overworking or overheating due to insufficient airflow.
Think of the return air flow as the system "breathing in" the old air so it can "breathe out" fresh, conditioned air.
Components Involved
Key parts of the return air system include:
- Return Air Grilles: Openings in rooms where air is drawn into the system.
- Return Ductwork: The pathways (usually large sheet metal or flexible ducts) that carry the air back to the air handler.
- Air Filter: Located near the air handler, this is where return air is cleaned.
- Indoor Air Handler/Furnace: The central unit that pulls in the return air for conditioning.
In essence, the return air flow is the fundamental process by which used indoor air is recycled, filtered, and re-conditioned by your furnace or AC before being redistributed throughout your home.
