Variable Air Volume (VAV boxes) are used in HVAC systems to better control air flow to a specific zone.
Traditional air systems are a constant air system, with only control on the air temperature. VAV boxes allow you to control the temperature of the room by controlling air volume, not air temperature alone.
WHAT IS A VAV BOX
VAV boxes are a simple metal shell, damper, control components, inlet and outlet connection points. The more complex VAV boxes have blower components, coils, and a variety of different options.
TYPES OF VAV BOXES HVAC
Traditional, fan-powered and reheat.
As inferred by each of their names, traditional VAV boxes are very simple and can be thought of as a damper controlled by a thermostat. Fan-powered VAV boxes are similar with the addition of a fan, frequently used on low pressure systems. Reheat coils in the VAV box allows you to have additional control (which increases efficiency) of the air temperature directly at the VAV box.
VAV BOX APPLICATION
Typically VAV boxes are used on larger, high pressure systems, when the equipment is serving a variety of areas and needs independent control. Due to the higher room controllability, these systems are used in more complex applications. Typically we see them in large retail stores, auditoriums, office spaces, schools and some larger homes.
INSTALLATION
Manufacturer installation instructions should be adhered to. Take note to not put screws into the coil or into the damper. Furthermore, ensure that the coils are left-hand or right-hand and install accordingly.