What is the function of economizer in Air Handling Unit (AHU)?

Economizers operate by pulling cooler outside air into buildings, reducing the load on the mechanical cooling system.

As part of the HVAC control system, an economizer is designed to save energy, typically reducing overall cooling energy consumption by twenty to thirty percent.

Here’s how an economizer works.

Using a collection of dampers, sensors, actuators, and logic devices, a economizer decides how much outside air can be brought into a building, allowing the load on the cooling system to be reduced.

Dampers regulate the amount of air introduced, recirculated, or exhausted from the building. Outdoor temperature sensors and logic controllers determine whether conditions are right for the economizer to operate, and govern the operation of the outside air damper. Actuators open or close dampers based on signals from the logic controllers.

Economizer are generally provided to reduce the building load by using the cool outside air to cool the indoor space of building.  

Good controls and valves or dampers, as well as maintenance, are needed to ensure proper operation of the air- and water-side economizers.

It is used only when the temperature of the outside air is less than the temperature of the recirculated air, conditioning with the outside air is more energy efficient than conditioning with recirculated air.

Economizer are not appropriate in hot and humid climate.

Economizers operate by pulling cooler outside air into buildings, reducing the load on the mechanical cooling system. As part of the HVAC control system, 

An air-side economizer is an HVAC control system that can provide significant cooling energy savings when properly specified, installed, commissioned, and maintained. Unfortunately, the economizer’s collection of dampers, actuators, linkages, sensors, and controllers rarely achieves its savings potential. Estimates indicate that only about one in four economizers works properly, with the remaining three providing sub-par performance or, worse yet, wasting prodigious amounts of energy. Failures are a result of maintenance deficiencies, improper control, or systemic problems. A healthy economizer begins life with a good design concept, careful specification of its constituent components, and performance testing of its operation under a variety of conditions. As time passes, it is important to retest the system periodically. Although advances in computer-based diagnostics can help identify malfunctioning systems, the human element is still essential to maintaining these systems.

Economizers operate by pulling cooler outside air into buildings, reducing the load on the mechanical cooling system.

As part of the HVAC control system, an economizer is designed to save energy, typically reducing overall cooling energy consumption by twenty to thirty percent.

The Economizer device is built in or retrofitted to rooftop equipment. It permits the unit to use outside air for cooling, provided the air is below a certain temperature & humidity is also low. Such type of cooling is called as "free cooling" because it cools the building without the use of energy required to run a compressor.

One of the important reasons to use an economizer is to save money on electricity. The longer outside air can be used for cooling, the longer the compressor can remain off. Also the economizer can actually extend the life of the equipment - provided the system is maintained properly.

Economizer are the device that use  to control the AHU if the required temperature inside the room has been meet it signal the control valve to shut down the flowing of cold water into the AHU by activating the DRV to bypass the cold water back to the cheller