HVAC Pictures VAV Box (Variable Air Volume)Previous | Home | Next |
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The variable air volume box or VAV box is a commercial solution to adding multiple zones to large buildings. VAV boxes offer zoning solutions so that seperate zoning demands or temperature selections can be maintained in different areas of the building. If the president of the company wats the temperature in their office to be 70 degrees Fahrenheit but the vice president wants their office to be 74 degrees Fahrenheit then it is possible with the VAV zoning system as long as their VAV boxes are on different zones.
This particular VAV box in the picture is not fan powered. It relys on the main VAV air handling unit to provide all the air. Generally, when a fan powered VAV box is calling for heat the damper inside the VAV box closes down so that minimal CFM's are coming through the primary duct from the air handler. The fan turns on an pulls air from the plenum space above the ceiling. This plenum air is normally warmer than the air inside the occupied space. The heating system kicks in and adds heat to the air until a setpoint is attained. The heat for a VAV box can typically be hot water or electric heat strips. The VAV box in the picture has hot water reheat.

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