Slide 1

Heating, Ventilation and Air Conditioning (HVAC) SystemsModule (1.1) Types of A/C Units and SystemInstructorEng. Juma Yousef Juma-Getco

HVAC SYSTEM OPERATION AND TYPES

Types of A/C Units and System according to Air Cooling Methods2) CH-Chilled Water1) DX-Direct Expansion

Types of A/C Units and System according to Air Cooling Methods1) DX-Direct Expansion2) CH-Chilled Water

Interior- (COLD AIR)

Indoor UnitFreon Cooling WaterCH. W. Cool AirFreon Cooling Air

DX Units types

DX-Direct Expansion

DX-Components

DX-Package UnitDX-Ducted Split

*To be fixed in lower floors at multi story villas.*multi story buildings.*Occupied less outer space & reduce ducting.*Can connect more than one room.*Give more flexibility for decoration.*Cheaper than package units.*Difficult to replacing the future if needed.*Efficiency Ratio: 1.8 kw per ton in average. * .* .* .* .* * .* .* .* : 1,8 . Features

Ducted Split Unit

Ducted Split Unit

Package Unit

* To be fixed at villas of one floor.*To be fixed at higher floor in multi story villa.*Easier to maintain & repair*Less inconvenience.*Easier to replace in the future.*Efficiency Ratio: 1.6 kw per ton in average * * * * .* .* : 1,6 Features

PKG in Duty

Mini-Split Unit*To be fixed in lower floors at multi story buildings.*Occupied less outer space & reduce ducting.*Can't connect more than one room.*Give more flexibility for decoration.*Cheaper than package units.*Easiest to replace in the future if needed.*Efficiency Ratio: 2.0 kw per ton in average. * .* .* .* .* .* .* .* : 2,00 / Features

Split Unit Working

Mini-Split Unit*Stylish Decorative Unit..*Occupied less inside space & reduce ducting.*Can't connect more than one room.*Give more flexibility for decoration.*Cheaper than package units.*Easiest to install & replace in the future if needed.*Drain Pump for Condensate Water*Efficiency Ratio: 2.0 kw per ton in average. * .* .* .* .* . . .* : 2,00 / Features

Types of Mini-Splits

Decorative Units provide Flexibility, fast to install, cheaper and easy to replace

Multi-Split Unit*Can be fixed various building types.*Flexible operation matches space usage. *Occupied less outer space.*Cond. Unit can be fixed as far as 50 mtr.*Optimum operation with higher efficiency. * .* .* .* .* . Features

VRF-Reliability

VRF-Flexibility

VRF-Components

Chillers types

22

Air Cooled Package Chiller

Chiller Components

Air Cold Chiller

Water Cold Chiller

Industrial air conditioner-

Condenser types

Air cooled units absorb heat from the indoor space and rejects it to ambient air.

Condensercompressor, propeller fans and controls

These are the most common system used in residential and light commercial applications. PARTSCondenser Air Cooled System

Chilled Water System with Air Cooled Condenser

Water cooled units absorb the heat from the indoor space and rejects that heat to water which in turn may either reject heat via fluid coolers or cooling towers, or dry air coolers with adiabatic kits.

higher coefficient of performance (COP). most common multi-storey offices, hotels, airports and shopping complexes. Condenser Water System Cooling Tower

Chilled Water System with Water Cooled Condenser

Condenser Water System air cooled unit water cooled unit

H2O

Compressor types

Rotary Compressor -

-Reciprocating Comp.

Full Strokes

Sealed -Semi-Sealed-

-Reciprocating Comp.

Scroll Compressor

Compression Method

Screw Compressor

Compression Method

Compression Method

Compression Method

New Compression Method

Turbo core Compressor

Turbo core Compressor

Turbo core Chiller

Range of Applications of CompressorsDomesticRefrigerators& FreezersAutomotiveAir CondgRoom AirConditionersUnitary AirConditioners& Heat PumpsCommercialAir Condg &RefrigerationLarge AirConditioning

Cooling Capacity

Fractional200 kW (50 tons)Reciprocating

Fractional10 kW (3 tons)Rotary

5 kW (1.5 tons)70 kW (20 tons)Scroll150 kW (40 tons)1500 kW (400 tons)Screw350 kW (100 tons) and upCentrifugal

50

Application ConsiderationsThe refrigerant and application determine FlowLift PD Compressors are ideally suited for higher liftCentrifugal Compressors have high volumetric flow

50

Air Handling Units

FAN-COIL UNIT

FCU-Fan Coil Unit is the part of Chilled Water System that deliver cooling to independent zones. These typically used in separate rooms/guestroom and small offices with limited ductwork for better air distribution. / , .

FAN COIL UNITIt part of anHVACsystem found in residential, commercial, and industrial buildings.A simple device consisting of a heating or cooling coil andfan.Used to control the temperature in the space where it is installed, or serve multiple spaces.It is controlled either by a manual on/off switch or by thermostat.Fan coil units are more economical to install than ducted or central heating systems withair handling units.They can be noisy because the fan is within the same space.

A/C Unit is: Fan + Coil = FCU

Fan Coil System - AdvantagesCentral equipment may be sized smaller by taking advantage of building heating and cooling diversity. The system requires only piping installation which takes up less space than all-air duct systems. It is usually easier to install wire and water pipes than ducts making this a good choice for retrofit applications. Unoccupied areas of the building may be isolated and shut down, saving money. Zones can be individually controlled. Can take up to 100% outside air capability (see next slide).

Fan Coil Unit FCU Components

DESIGN - A fan coil unit may be concealed or exposed within the room or area that it serves.An exposed fan coil unit may be wall mounted, freestanding or ceiling mounted.It typically include an appropriate enclosure to protect and conceal the fan coil unit itself.Return airgrille and supply airdiffuserset into that enclosure to distribute the air.A concealed fan coil unit will typically be installed within an accessible ceiling void or services zone.The return air grille and supply air diffuser will be ducted to and from the fan coil unit.

OPERATION - The coil receives hot or cold water from a central plant, and removes heat from or adds heat to the air throughheat transfer.Traditionally fan coil units can contain their own internalthermostat, or can be wired to operate with a remote thermostat.In most modern buildings with aBuilding Energy Management System(BEMS), the control of the fan coil unit will be by a local digital controller. equipment for adding heat to the building's water.

Fan coil units circulate hot or cold water through a coil in order to condition a space.The unit gets its hot or cold water from a central plant, ormechanical roomcontaining equipment for removing heat from the central building's closed-loop.The equipment used can consist of machines used to remove heat and

TYPES -

Conceal FCUDecorative FCU Exposed

Conceal FCU with Duct

TYPES -

Two-pipe FCU for Cooling OnlyFour-pipe FCU for Cooling/Heating

TYPES - Low Static FCU (No Duct or Small DuctMedium Static FCU with ducting

High Static FCU with more ducting

AHUAir Handling Unit

AHU System - DisadvantagesLong, big in size and expensive GI Duct.Taking extra space from the building.Relatively high noise levels (at high output) Might have week return from far branch.High operating and maintenance costs(for changing the filter and fan)

What is AHU?An air handler, or air handling unit (often abbreviated to AHU), is a device used to condition and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large metal box containing a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers.

Air handlers usually connect to a ductwork ventilation system that distributes the conditioned air through the building and returns it to the AHU. Sometimes AHUs discharge (supply) and admit (return) air directly to and from the space served without ductwork.

waterAir-

1

2

3

4

CONSTRUCTION AND MATERIALSThe air handler is normally constructed around a framing system with metal infill panels as required to suit the configuration of the components In its simplest form the frame may be made from metal channels or sections, with single skin metal infill panels. The metal work is normally galvanized for long term protection. For outdoor units some form of weatherproof lid and additional sealing around joints is provided.Larger air handlers will be manufactured from a square section steel framing system with double skinned and insulated infill panels. Such constructions reduce heat loss or heat gain from the air handler, as well as providing acoustic attenuation. Larger air handlers may be several meters long and are manufactured in a sectional manner and therefore, for strength and rigidity, steel section base rails are provided under the unit.

AHU Air Handling Unit

AHU Operation

COMPONENTS

An air handling unit; air flow is from the right to left in this case. Some AHU components shown are1 Supply duct2 Fan compartment3 Vibration isolator ('flex joint')4 Heating and/or cooling coil5 Filter compartment6 Mixed (recirculated + outside) air duct

VERTICAL AHU

HORIZONTAL AHU

CELING MOUNTED AHUAHU classified on basis of installation

VERTICAL AIR HANDLING UNITS

designed for vertical in room mountingVAHU comes with a fan and a cabinet that can produce high profile static pressures without occupying the larger footprint area

FEATUREShigh performancecost effective small air-handling Suitable for spaces with less areaAPPLICATIONClassroomLaboratoriesPharmaceutical labs

HORIZONTAL AHU

Features:Low costReliableEasy to useHigh durability

Applicationhomesofficesinstitutionsfactories

floor mounted air handler is usually a large metal box containing a bowler, heating or cooling element

CEILING MOUNTED AHU

Can be suspended from the ceiling and hence require no floor spaceNoiseless units and can be placed above the false ceiling in the conditioned areaUnits are unobtrusive giving flexibility to the design of the interiorFeatures :Cost efficientHigh quality productEasy to usePerfect functionality

Applications :Shopping MallsMultiplexesSmall OfficesWare houses

AHU-according to feeding Area

single-zone Multi-zones

Draw through type:fan located after cooling coil

TYPE OF AHU DEPENDING ON LOCATION OF FANBlow through type: fan located before cooling coil

Draw through type:fan located after cooling coilTYPE OF AHU DEPENDING ON TYPE OF FANBlow through type: fan located before cooling coil

Draw through typeBlow through typeLower condensation of waterHigher condensationLess air leakageMore chances of air leakingheat generated by fan andmotor added to air downstreamof cooling coil, requiring acolder leaving-coil temperature to achieve adesired supply-air temperatureHeat generated by the fan and motor is added to the air upstreamof the cooling coil,allowing for awarmer leaving-coil temperature to achieve adesired supply-air temperature

TYPE OF AHU DEPENDING ON LOCATION OF FAN

PACKAGED AHUcommon in smaller buildings and commercial applications, particularly as rooftop units. Packaged unit contain fans, coils, filters, and dampers in a single casing casing include air conditioning compressors, heaters such as gas burners, electric heating coils, or heat pump coils. serve single temperature zones, VAV serving multiple terminal boxes (zones) are available. FEATURESCompact lower initial costsDISADVANTAGESinefficient maintenance intensive

ADVANTAGESModular construction and wide selection of air handling unit sizesWide application range Low energy consumptionLow risk of condensation : air tightEasy installation and adaptability to building conditionEasy maintenance: hygienically friendly

DISADVANTAGESAHU is physically large and requires careful planning in terms of a suitable location. The space required for ducting and the corresponding holes through building fabric require careful co-ordination with builders and other mechanical services within the room. Rooms with variable or moving sources of heat gain such solar gain traversing around the room require sophisticated duct work and controls. Zone heaters may have to be incorporated into duct branches.

lifting or rigging the AHU to the sitelocate the AHU in the AHU roompreparing unit for the installationassembling the unitcabinet installation fan installationelectrical installation coil and piping installation sheetmetal installationfinal installationcontrols installation final sensor and actuator ..calibration verification

INSTALLATION PROCESS

Duct & Accessories

COMPONENTSFiltersto provide clean dust-free air to the building occupantsIt may be via simple,HEPA,electrostatic, or a combination of techniques. Gas-phase and ultraviolet air treatments may be employed as well.Filtration is typically placed first in the AHU in order to keep all the downstream components clean. Depending upon the grade of filtration required, typically filters will be arranged in two (or more) successive banks with a coarse-grade panel filter ..provided in front of a fine-grade bag filter.

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. Such conditioning is provided by heat exchanger coil(s) within the AHU air stream, such coils may bedirectorindirectin relation to the medium providing the heating or cooling effect.Coils are typically manufactured from copper for the tubes, with copper or aluminum fins to aid heat transfer.

Heating and/or cooling elements

Ifdehumidificationis required, then the cooling coil is employed toover-coolso condensation occurs. A heater coil placed after the cooling coil re-heats the air to the desired supply temperature. This has the effect of reducing therelative humiditylevel of the supply air.

Dehumidifier

HumidifierHumidification is often necessary in colder climates where continuous heating will make the air drier, resulting in uncomfortable air quality

Various types of humidification may be used:Evaporative: dry air blown over a reservoir will evaporate some of the water. The rate of evaporation can be increased by spraying the water onto baffles in the air stream.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.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. This type of humidifier can quickly clog if the primary air filtration is not maintained in good order.

Humidifier-Humidification is often necessary in colder climates where continuous heating will make the air drier, resulting in uncomfortable air quality Various types of humidification may be used:

Evaporative: dry air blown over a reservoir will evaporate some of the water. The rate of evaporation can be increased by spraying the water onto baffles in the air ..stream.

Humidifier-Humidification is often necessary in colder climates where continuous heating will make the air drier, resulting in uncomfortable air quality Various types of humidification may be used:Vaporizer: steam or vapor from a boiler is blown directly into the air .stream.

Humidifier-Humidification is often necessary in colder climates where continuous heating will make the air drier, resulting in uncomfortable air quality Various types of humidification may be used: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.

Humidifier-Humidification is often necessary in colder climates where continuous heating will make the air drier, resulting in uncomfortable air quality Various types of humidification may be used:

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. This type of humidifier can quickly clog if the primary air filtration is not maintained in good order.

Mixing chamberIn order to maintain indoor air quality, air handlers commonly have provisions to allow the introduction of outside air into, and the exhausting of air from the building. 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 hasdamperscontrolling the ratio between the return, outside, and exhaust air.

Blower/fanAir handlers typically employ a large blower. The blower may operate at a single speed, offer a variety of set speeds, to allow a wide range ofair flowrates. Flow rate may also be controlled by inlet vanes or outlet dampers on the fanMultiple blowers may be present in large commercial air handling units, typically placed at the end of the AHU and the beginning of the supply ductwork .

Heat recovery deviceA heat recovery deviceheat exchangerof many types, may be fitted to the air handler between supply and extract airstreams for energy savings and increasing capacity. These types more commonly include for:

Heat recovery deviceRecuperate, or Plate Heat exchanger: A sandwich of plastic or metal plates with interlaced air paths. Heat is transferred between airstreams from one side of the plate to the other. The plates are typically spaced at 4 to 6mm apart. Heat recovery efficiency up to 70%.

Heat recovery deviceThermal Wheel, or Rotary heat exchanger: A slowly rotating matrix of finely corrugated metal, operating in both opposing airstreams. When the AHU is in heating mode, heat is absorbed as air passes through the matrix in the exhaust airstream, during one half rotation, and released during the second half rotation into the supply airstream. When the AHU is in cooling mode, heat is released as air passes through the matrix in the exhaust airstream, during one half rotation, and absorbed during the second half rotation into the supply airstream. Heat recovery efficiency up to 85%.

ControlsControlsare necessary to regulate every aspect of an air handler, such as:flow rate of air, supply air temperature, mixed air temperature, humidity, air quality. Common control components include temperature sensors, humidity sensors, sail switches,actuators, motors, and controllers.Vibration isolatorsThe blowers in an air handler can create substantial vibration and the large area of the duct system would transmit this noise and vibration to the occupants of the building. To avoid this, vibration isolators (flexible sections) are normally inserted into the duct immediately before and after the air handler and often also between the fan compartment and the rest of the AHU. The rubberized canvas-like material of these sections allows the air handler components to vibrate without transmitting this motion to the attached ducts.

Overall View

AHU System - DisadvantagesLong, big in size and expensive GI Duct.Taking extra space from the building.Relatively high noise levels (at high output) Might have week return from far branch.High operating and maintenance costs(for changing the filter and fan)

Full Equipped FAHU

By Eng. Juma Yousef Juma jumayjuma@gmail.com +971-50-4948385