VAV AIR CONDITIONING SYSTEM

WHAT IS VAV AIR CONDITIONING

• A variable-air-volume (VAV) air conditioning system varies the volume of constant temperature air that is supplied to meet the changing load conditions of the space

VAV AIR CONDITIONING SYSTEM

COMPONENTS OF VAV AIR CONDITIONING

Terminal unit

• It is a sheet-metal assembly installed upstream of its respective space diffusers. The unit consists of an air-modulation device, control hardware and, depending on the system application, possibly a heating coil, a filter.

Single Duct cooling

Air supplied to the space by the terminal unit varies as the space loads change. The supply airflow to the space is reduced as the cooling load in the space decreases. Responding to the space thermostat, the primary airflow is modulated between maximum and minimum settings. The maximum setting is determined by the design cooling load of the space and the minimum setting is normally determined by the space ventilation requirement or minimum airflow for proper diffuser selection

Space Heating With a VAV system

Single duct VAV terminal units can directly provide heat to a space.

Adding a heating coil to each cooling-only unit or by mixing the primary air with warm air before it is delivered to the space.

WHY VAV AIR CONDITIONING SYSTEM

Calculation of full load and part load. Refrigeration energy savings are realized at part load conditions. Space humidity levels suffers due to the warmer supply air condition.

WHY VAV AIR CONDITIONING SYSTEM

FULL LOAD PART LOAD

The VAV system produces a balance by modulating the volume of constant 12.8° supply air

Advantages of VAV air conditioning

• One reason to use a VAV system is the potential for part-load energy savings.

• The air volume reduction creates an opportunity to reduce the fan energy required to move this air

• The reduced airflow across the cooling coil causes the refrigeration system to throttle back in order to stabilize the primary air temperature

Comparison with CV air conditioning

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