What are VAV units?

VAV units, or Variable Air Volume systems, supply constant temperature air to an area while the volume of air varies as opposed to a conventional HVAC system which has constant volume and varies the air temperature.

How does VAV change the volume of air supplied?

VAV stands for Variable Air Volume. In its simplest form, VAV systems use varying airflow at a constant temperature to heat and cool buildings. This is opposite of a CAV (or Constant Air Volume) system, which supplies consistent air flow at varying temperatures to heat or cool a space.

What are the different types of VAV?

There are two primary types of VAV systems—single-duct and dual-duct.

What are VAV controls?

Variable Air Volume Control System Variable Air Volume (VAV) is a type of heating, ventilating, and/or air-conditioning (HVAC) system. The VAV Zone Controller has a built-in actuator and maintains zone temperature by operating the terminal fan and regulating the flow of conditioned air into the space.

What is the function of VAV?

VAV systems supply air at a variable temperature and airflow rate from an air handling unit (AHU). Because VAV systems can meet varying heating and cooling needs of different building zones, these systems are found in many commercial buildings.

What is a multi zone VAV system?

Background. Multiple-zone VAV systems have existed for more than forty years. One reason they continue to remain popular is that they save fan horsepower at part load by reducing airflow. These systems can utilize direct expansion or chilled- water cooling and serve just a few or many zones.

What is a variable air volume or VAV system in HVAC?

Variable Air Volume (VAV) Basics 1 One of the efficient ones that help in practical ways is the VAV system. 2 Variable Air Volume system is the core advancement that is equipped with all the core advantages. 3 VAV is a ventilating, air conditioning, or heating system that provides adequate protection from changing weather conditions.

How much air can be turned down in a VAV unit?

Typically, VAV boxes have been selected to be able to turn-down to 30% of maximum flowrate to maintain air distribution. At lower flowrates, cold air ‘dumping’ and the lack of mixing when supplying reheated air have often been associated with a poorly conceived or operated VAV system. Figure 4: A generic pressure-independent VAV terminal unit.

How does constant modulation work in a VAV system?

This constant modulation requires variable refrigerant capacity in the form of multi-stage or variable refrigerant compression and generally a blower fitted with a VFD (variable frequency drive). However, older VAV systems often used an adjustable vane at the blower inlet to vary the air volume.

How does a vav Zone Controller maintain temperature?

The VAV Zone Controller has a built-in actuator and maintains zone temperature by operating the terminal fan and regulating the flow of conditioned air into the space. Buildings with diverse loading conditions can be supported by controlling the local terminal’s supplemental heat.