Fans and Ventilation Overview
- Fans and ventilation are essential for moving air through ductwork and within a house's structure.
- Fans push air through the ductwork, while ventilation allows stale air to escape.
Fan Functionality
- The fan that powers air through the ductwork is part of the air handler or furnace.
- Fan size is determined by the amount of air needed to maintain equilibrium with the HVAC system.
- Fans are measured in CFM (cubic feet per minute), indicating the volume of air they can move.
- Example: A typical system requires 400 CFM per ton of cooling, so a 3-ton system uses a fan rated at 1200 CFM.
- Fans are also rated for static pressure, which is the resistance air faces as it moves through the ductwork.
- Factors like lengthy duct runs or numerous elbows increase static pressure, reducing the fan's CFM capability.
Ventilation
- Ventilation ensures that air is properly supplied and then returned from each room, maintaining balanced air pressure.
- Examples of home ventilation include:
- Bathroom exhaust: Removes moist or unpleasant air.
- Kitchen exhaust: Eliminates cooking fumes and odors.
- Proper ventilation is crucial for maintaining neutral pressure in the house, ensuring fresh air replaces the air exhausted from bathrooms and kitchens.
Importance of Air Circulation
- Ceiling fans increase comfort and help circulate air within a room, enhancing overall airflow.
- Without proper air circulation and ventilation, a house may leak air from outside (e.g., through a crawl space or basement).
- This leakage forces the HVAC system to work harder and may introduce pollutants like mold and moisture into the living space.
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