An air handler is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system.

1. Submitted to: Presented by:
Mr. Yogendra Narayana Jyoti Singh
Research Scholar ME (Regular)
EE department Branch - I & C
NITTTR Chandigarh Roll No:142511

2. Contents
• Introduction
• Operation of Air Handler
• Components of Air Handler

3. Introduction
• An air handler is a device used to regulate and circulate air as part of a
heating, ventilating, and air-conditioning (HVAC) system.

4. Operation of AHU

5. Components of Air Handler
• Blower/fan
• Heating and/or cooling elements
• Mixing chamber
• Filters
• Dampers
• Humidifier
• Heat recovery device
• Controls
• Vibration isolators

6. Blower/Fan
• The blower pushes the air through the system and ducts.
• It is typically a centrifugal fan which is a fan wheel that blows the air at a
right angle to the intake direction, using centrifugal force to accelerate the
air.
• Backward curved or inclined blades have higher efficiency than forward
curved or radial blades and airfoil blades, backward curved with double
thickness, have the highest efficiency.
• The blower controls the flow rate of air by operating at a set speed or
variable speeds.

7. Heating/Cooling Element
• Air handlers may need to provide heating, cooling, or both to change the
supply air temperature, and humidity level depending on the location and
the application.
• Air handling units contain coils that circulate hot water or steam for
heating, and chilled water for cooling.
• Cooling coils will also employ eliminator plates to remove and drain
condensate.
• Downstream temperature sensors are typically used to monitor and control
'off coil' temperatures, in conjunction with an appropriate motorised
control valve prior to the coil.

8. Mixing Chamber
• The mixing chamber combines the specified proportions of outside air and
return air into the supply air.
• Mixing in outside air keeps the interior air fresh by supplying oxygen.
• In temperate climates, mixing the right amount of cooler outside air with
warmer return air can be used to approach the desired supply air
temperature.
• A mixing chamber is therefore used which has dampers controlling the
ratio between the return, outside, and exhaust air.

9. Filter
• Filters remove particulates including dust, pollen, and mold from the air
and are typically a fibrous material.
• It may be via simple low-MERV pleated media, HEPA, electrostatic, or a
combination of techniques. Gas-phase and ultraviolet air treatments may
be employed as well.
• Filters must be replaced regularly to prevent clogging or contamination.

10. Low efficiency (panel-type) Medium efficiency (bag-type)
HEPA and ULPA filters Activated carbon filter

11. Dampers
• A damper is a valve or set of blades that open and close to control the air
flow.
• Dampers are located in the mixing chamber to control the ratio of return
air to outside air and the amount of exhaust air.
• They also regulate the flow rate of supply air in the system.

12. Humidifier
• A humidifier is needed in cold climates to increase the relative humidity of
dry outside air.
• Evaporative: dry air blown over a reservoir will evaporate some of the
water.
• Vaporizer: steam or vapor from a boiler is blown directly into the air
stream.
• Spray mist: water is diffused either by a nozzle or other mechanical means
into fine droplets and carried by the air.
• Ultrasonic: A tray of fresh water in the airstream is excited by an
ultrasonic device forming a fog or water mist.

13. • Wetted medium: A fine fibrous medium in the airstream is kept moist with
fresh water from a header pipe with a series of small outlets. As the air
passes through the medium it entrains the water in fine droplets.

14. Heat Recovery device
• A heat recovery device is a heat exchanger placed between the exhaust
and supply air streams.
• It creates energy savings and increased capacity by transferring heat from
the exhaust air to the supply air before it is conditioned.
• Some common types are cross plate heat exchanger, thermal wheel, run
around coil, and heat pipe.

15. Controls
• Controls manage the various components of the air handler by regulating
air flow rate, temperature, humidity, and air quality.
• Controls can be manual or automatic and range in complexity.
• Simple systems may be just on/off control with or without temperature
control.
• More complex system controls may be fully automated using temperature
sensors, humidity sensors, actuators, and motors.

16. Vibration Isolator
• Air handler blowers, especially in large systems, create a large amount of
vibration and noise that can be transmitted through the ducts.
• Vibration isolators are flexible sections often placed on both end of the air
handler and between the fan and the rest of the AHU.
• The fan compartment can also be placed on springs to further limit
vibration.
• The vibration isolators dampen the vibration transmitted to the ducts.

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