AHU vs HVAC: Difference and Comparison

The circulation of air and re-conditioning of air can be done by the AHU and HVAC. Both are machines that help to circulate the air. Various types of AHU and HVAC are available nowadays.

Key Takeaways

  1. AHUs (Air Handling Units) focus on air circulation, filtering, and temperature control; HVAC (Heating, Ventilating, and Air Conditioning) provide a comprehensive system for air control.
  2. HVAC systems incorporate AHUs as a component, with the primary distinction being that HVACs include heating and cooling functions.
  3. AHUs and HVACs improve indoor air quality, but HVAC systems offer greater control over various environmental factors.


The difference between AHU and HVAC is the device. AHU is a unit inside the HVAC, whereas HVAC is a whole system in air heating and circulating. The Air handler handles only the ventilation part, whereas HVAC handles the heating, ventilating, and air conditioning part. In simple, the HVAC handles the entire system.


An Air handler is a device or part of a heating, ventilating, and air conditioning system. The primary focus of the air handler device is to regulate and circulate the air.

Air handler is nothing but a large metal box that contains a blower, filter, attenuators, and dampers. The blower is used for heating and cooling elements, the filter is to purify the air, attenuators for sound.

The ductwork ventilation system is directly connected to the air handlers. The ductwork ventilation system is nothing but it distributes the conditioned air to the building. Finally, it returned to the AHU directly.

Heating, ventilation, and air conditioning is a system with many smaller units. HVAC uses different types of technologies to execute the output.

It primarily focuses to control the temperature, humidity, and purity of the air. In the enclosed space the HVAC can execute it works properly.

Thermal comfort is the fundamental goal of Heating, ventilating, and air conditioning system. HVAC provides a high range of indoor air quality.

HVAC work behind various engineering techniques namely thermodynamics, fluid mechanics, and heat transfer refrigeration.

Comparison Table

Parameters of comparisonAHUHVAC
Stands forAHU stands for Air Handling UnitHVAC stands for Heating Ventilation and Air Conditioning Unit
UnitAHU is a sub-unitHVAC is the central unit
TypesAHU has three typesHVAC has no types
Total number of componentsAHU has six componentsHVAC has four components
Major functionAHU has one major functionHVAC has three major function

What is AHU?

The Air handler unit is a vital part of the heating, ventilating, and air conditioning system. Air handler work along with ductwork ventilation system, but sometimes it works without ductwork system.

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In those times it discharges and returns directly from the space. the local use air handlers are small in size, which is called terminal units instead of air handlers. The terminal units contain only filters, blowers, and coil for their purpose.

Since it is used locally in small buildings does not require to be in large metal boxes. The units present inside the terminal units are blower units and fan coil units.

Air handlers are available in large metal boxes that condition a hundred percent outside air without re-circulated air is called a Makeup air unit(MAC) or Fresh Air Handling Unit(FAHU).

These two types are somewhat different from normal AHU, and these two are costlier when compared to a normal air handler. The air handlers are produced for outside usage.

They are mainly fitted in the roofs of the houses. Those are called Packaged Units (PU), or Rooftop Units(RU).

The components present in the air handler are the supply duct, Fan compartment, Vibration isolator, heating, and cooling coil, filter compartment, and mixed air duct.

The supply duct will supply the sir inside, fan compartment is for conditioning, vibration isolator is used for a flex joint, filter compartment will filter the air, finally, the mixed duct is used for both the outside air and re-circulated air.

The three different air handlers are Mall Air Handlers, Makeup Air Unit, and Roof Top Unit. The air handlers can be classified based on application, the direction of flow, package model, and zone control.

What is HVAC?

The heating, ventilating, and air conditioning system has huge mechanics behind it. It needs many smaller subunits and principles to work properly.

HVAC become an essential feature in apartments, single buildings, office buildings, skyscrapers, malls, and hospitals. Even vehicles need heating, ventilating, and air conditioning system.

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Vehicles like cars, trains, and airplanes HVAC become a necessary one. The marine environment uses HVAC widely in ships and submarines. The ventilation process in HVAC is vital which provides high-quality air to the indoors.

The ventilation process in HVAC includes many features. It did oxygen replenishment, removal of dust and moisture, and control the temperature.

It keeps the building moisture with quality air. It involves two different types. Mechanical ventilation and natural ventilation.

Heating, ventilation, and air conditioning are the three major functions of the HVAC system, and so we called the name HVAC system. The HVAC system provides pressure to increase the quality between spaces.

The HVAC technician must know about heating, ventilating, and air conditioning. He may have the situation to repair the things related to that.

The mechanics behind the HVAC is quite hard. They need many smaller subunits to perform the tasks. The air handling unit is one sun unit present inside the HVAC system.

Each country follows its own methods according to the environment. Some huge buildings install one or more HVAC systems for better air quality.

Main Differences Between AHU and HVAC

  1. When compared to AHU, the HVAC is a big system with huge mechanics.
  2. The Air Handling Unit is only a ventilation controller, whereas HVAC is the controller of the whole unit.
  3. AHU has three different names, whereas HVAC has no different names.
  4. When compared to AHU, HVAC has more workload.
  5. When compared to AHU, the HVAC has many subunits and sub principles.
Difference Between AHU and HVAC
  1. https://dl.acm.org/doi/abs/10.1145/2821650.2821655
  2. https://www.tandfonline.com/doi/abs/10.1080/15623599.2020.1742638

Last Updated : 13 July, 2023

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