How does VAV AHU work?

How does VAV AHU work?

VAV systems supply air at a variable temperature and airflow rate from an air handling unit (AHU). Each VAV box can open or close an integral damper to modulate airflow to satisfy each zone’s temperature setpoints.

What is the difference between VAV and AHU?

Unlike a VAV system, AHUs in constant air volume (CAV) systems are always supplying the same amount of airflow regardless of the actually heating or cooling load. The following example highlights how changing the airflow affects the mixed air temperature in AHU unit: Outside Airflow is 2,000 cfm.

What is a VAV box in HVAC?

A VAV — i.e., Variable Air Volume — HVAC (heating, ventilation, and air conditioning) system that supplies air at varying levels or amounts at a constant temperature. These comprise of multiple VAV terminal units or boxes that diffuse air in specific areas of a large indoor space, such as an auditorium.

How do VAV boxes work?

The VAV regulates the volume of the air to the zone by opening or closing the damper, thus controlling the amount of conditioned air directed to the zone. Each zone in a building has a thermostat that controls the VAV, telling it when to open or shut the damper based upon the needs of the zone.

How are VAV boxes powered?

Typically, a VAV box consists of a few simple parts: the damper, the controller/actuator, and perhaps a coil for heating and cooling via electricity or water pumps. As the air passes through these boxes the actuator modulates the damper position which allows different amounts of airflow into the zone.

Do VAV boxes require power?

POWER SUPPLY IS INSTALLED ARE NOT REQUIRED WHEN THE ENCLOSURE & BACKPLATE LOCATION(S). NUMBER OF BOXES & MECHANICAL CONTRACTOR FOR SUPPLY(S). COORDINATE WITH SUPPLY & INSTALL POWER MECHANICAL CONTRACTOR TO VAV BOX 24V POWER SUPPLY(S).

What is face and bypass damper?

Face and bypass dampers are used in applications where two dampers are connected together allowing one damper to open while the other damper closes.

Which damper used in VAV?

A VAV terminal unit, often called a VAV box, is the zone-level flow control device. It is basically a calibrated air damper with an automatic actuator. The VAV terminal unit is connected to either a local or a central control system.

What is a variable air volume box (Vav)?

The primary air comes from a central VAV air handler through the primary duct system and the VAV Box distributes the air into a secondary duct system with the zone it controls. In a VAV system, it is all about controlling air flow and room temperature. Some Variable Air Volume boxes also have a heat source inside the box.

Why does my VAV box need more air when I turn it on?

If the VAV box is in air conditioning and cooling mode it requires much more air than when it is in heating mode. The amount of air entering the VAV box is regulated by air dampers that open when more air is required, and close to form a smaller opening when less is required.

What is the function of a VAV system?

It is designed to control the air flow to a specific area, called a “zone.”. The VAV regulates the volume of the air to the zone by opening or closing the damper, thus controlling the amount of conditioned air directed to the zone.

What happens when a VAV terminal is opened?

As VAV terminals open, the static pressure in the supply duct decreases, and the blower increases air volume to maintain the static. As the air volume increases, the system cooling capacity also needs to increase to maintain the supply air temperature.