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CLASSIFICATION OF HVAC CONTROL SYSTEMS,SENSORS,ACTUATORS AND CONTROLLERS

ANEURINE MATHEWS, SATHYA ,VIDYA SAGAR, Sunmugham

M-ARCH GENERAL HIETINTELLIGENT BUILDINGS ASSIGNMENT

HVAC SYSTEMS,UNITS,CONTROL,SENSORS,ACTUATORS,

DUCTS DESIGN,FANS, NEW TECHNIQQUES&

CASE STUDY

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INTRODUCTION TO HVAC-BASICS

DEFINTION

HVAC: Heating, Ventilation, Air Conditioning

Mechanical intervention to condition air to a preferred temperature and relative humidity

HVAC SYSTEMS

Are a Circular Stream of Moving Air: The Loop

Along Which:

Temperaturecan be Raised or Lowered

Humiditycan be Raised or Lowered

Filtrationcan Occur

Outside Air can be Added and Removed

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VARIOUS AC SYSTEM

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Windows AC

These types of AC are designed to be fitted in window sills. A single unit of Window Air Conditioner houses all the

necessary components, namely the compressor, condenser, expansion valve or coil, evaporator and cooling coil enclosed

in a single box. Since a window AC is a single unit, it takes less effort to install as well as for maintenance.

Advantages

Single unit air conditioner

Less effort needed for installation

Costs lesser in comparison to other varieties

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Split AC

These are kits of 2 units, one internal and another external. The indoor unit installed inside a room intakes warm air

and throws in cold air. The outdoor unit on the other hand is installed out of the house. It contains the compressor

and is linked to the internal unit via drain pipes and electric cables. This external unit throws out the warm air.Advantages

Internal unit takes up less space for installation

Usually more silent than window ACs

Minimally affect your home decor

Can be installed in room with no windows

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Floor mounted Split AC

Tower AC

These are also known as floor-standing air conditioners. Like

split ACs, a tower AC set consists of 2 units- one internal andan external. However, the indoor unit doesnt need wall

installation. It rather occupies some space on the floor. Tower

air conditioners usually have high cooling capacity and

suitable for very large rooms.

Advantages

Suitable for high capacity cooling

Ideal for large rooms at home and in offices

Doesn't need windows or wall installation

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CEILING TYPE EXPOSED SYSTEM

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CEILING TYPE HIDE AWAY

Unit is completely built into the ceiling and cool air is delivered via a duct system which complements the interior decor in

accordance with the shape of the room.Hidden in the ceiling, this model is designed for buildings that require floor level air conditioning for many individual rooms

or large areas, like restaurants, concert halls and hotels. Installation is not restricted by lighting fixtures or the building

layout and interior renovation is made easy by installing ventilation diffusers.

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CEILING CASSETTE SPLIT UNIT

These space-saving ACs are shaped like cassettes and are designed to be installed on ceilings. The panel of these air

conditioners is designed to blend with all kinds of home dcor. They are stylish, and are known to deliver fantastic

performances. Most cassette type air conditioners require no ducting. They are perfect for large spaces where windows or

split AC may not reach out.

Advantages

Best at saving space

Able to cool large areas where other ACs dont reach out

Blends with decor

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DX SYSTEM (DIRECT-EXPANSION SYSTEM)

A direct expansion air conditioning (DX) system uses a refrigerant vapour expansion/compression (RVEC) cycle to

directly cool the supply air to an occupied space.

DX systems (both packaged and split) directly cools the air supplied to the building because the evaporator is in direct

contact with the supply air,

Expansion refers to the treatment of the refrigerant (a valve reduces its pressure and temperature) prior to it entering

the evaporator. DX systems can come equipped with all the components in the unit (packaged system) intended for

installation on the rooftop or by the side of a building; or it may have some components installed inside the building

and some outside (split system). DX systems require a ventilation fan to distribute the cool air and resupply/re-circulate

it.

HOW IT WORKS

A RVEC cycle has four basic components; an evaporator, compressor, condenser, and thermal expansion controldevice.The evaporator(located insidethe supply air ductwork) absorbs heat through the process of expanding the

refrigerant flowing within it. The refrigerant then flows to a compressor which compresses it causing it to condense

in the condenser and release the heat it removed from the supply air. The condensed liquid refrigerant then flows

through the thermal expansion control device which controls the flow and pressure of the refrigerant back into the

evaporator.

Packaged SystemsPackaged DX units contain all 4 parts of the RVEC system, as well as fans and internal ducting.

These units are designed to be installed easily to serve local zones cooling needs; multiple units can be installed to

service multiple zones in a building.

Split SystemsThese systems generally have the evaporator and fans inside the building, while the rest of the RVEC

system components are a separate unit placed outside the building. This allows system designs that are more flexible,

allowing performance that can satisfy greater variations on system demands. Split units are made to an incremental

performance scale, meaning only certain working load sizes are available.

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DX SYSTEM (DIRECT-EXPANSION SYSTEM)

Air-cooled system: Refrigerant hot gas discharge from compressor is being cooled by fan driven by motorto induce

outside air to condense the refrigerant within the condenser coil.

Depending on the system requirements, the basic components of DX system can be categorized into various types ofequipment combinations for split system, built-up DX system and portable/window unit

Built-up DX system: dependent upon cooling capacity requirements which would necessitate larger equipment

combination similar to those in the split system.

Window or portable unit: is a one piece type of air-con equipment installed in wall opening or modified window casing

.

Water-cooled system: Refrigerant hot gas in the condenser coil is being cooled by re-circulating condenser water fromcooling tower.

Water-cooled system consists of water-cooled packaged unit, condenser water pump unit, and cooling tower, including

inter-connecting condenser water pipework

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SINGLE PACKAGE ROOF TOP UNIT)

CONDR

COIL

COMP

FAN

HEAT

ELECTRIC

HEATER

S.A. DUCT

S.A.

TERMINALR.A. DUCT

O.A.

E.A.

HEAT

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SPLIT SYSTEM

HVAC system split into 2 piecesCondensing unit located on roof (housescompressor, condenser coil, condenser

fan motor)Air handler located in space aboveceiling (houses blower assembly, evapcoil, air filters)Connected electrically and withrefrigerant pipingMost prone to refrigerant leaksespecially if long distance between

componentsMany times refrigerant lines are buriedin construction and inaccessible

COI

L

HEAT

AI

R

R.A. DUCT

O.A.

E.A.

FAN

C

O

N

D

R

C

OM

P

CONDENSING UNIT

REFRIGERANT

LINES

S.A. DUCT

POSSIBLE

ELECTRIC

HEAT

AIR HANDLING

UNIT

HEA

T

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Water Cooled Units

It requires water which used to cool the refrigerant in

the condenser .

Water is pump through the shell and tube condenserwhich is the part of the packaged unit

This water is than sent into a cooling tower outside

the air conditioned room where the heat is dissipated

in the atmosphere

Water cooled units give higher capacities and are

more power efficient owing to lower operating

pressure

Air Cooled Models

These aresuitable for places where water is scarce or

of hard quality or were there is no space for a cooling

tower

The heat is removed by away of an air cooled

condenser with a fan blowing through it .

It is mounted outside building in sunshade or a

terrace

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Advantages

They required a small plant room

They are serviced friendly bcozof easy accessibility

They can handle long ducts with used of more powerful fans

Large tonnage can be handle.

Interiors are clean and undisturbed as machines are placed in separate plat room

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The water-cooled type can be completely factory assembled, charged (with refrigerant) and tested.

Thus the laying of refrigerant piping, pressure leak testing, evacuation. Charging. etc. need not have to be carried out

in the field. This not only reduces the field labor, but also ensures a cleaner system, being assembled in the factory with

strict quality control procedures

The air-cooled type obviously cannot be factory assembled and charged. Laying of the refrigerant piping between the

indoor and outdoor units, pressure testing, evacuation, charging, etc. have to be carried out in the field.

Because of the scarcity of water, air-cooled units are favored,Though their capacity will be less than that of, the

watercooledcondenser using the same compressor. For the evaporator side, centrifugal fans are provided, which

can develop higher static pressure. So air distribution duct and grills can be connected to the unit. Air quantities

generally ware 10 to 11.3 m3 /min. (350 to 400

cfm) per ton

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Central system

Central system is an air conditioning system which uses a series of equipements to distribute cooling media to exchange

heat and supply conditioned air from one point (eg. plant room) to more than one rooms.

Central system normally uses water as the cooling media for larger buildings. The refrigerant inside the evaporator

absorbs heat from the water and this water is pumped to coils in order to absorb heat from the air used for space

conditioning. Systems that employ water chillers are commonly called chilled-water system.

Central air-conditioning system is a process of removing heat content from multiple sources in the building through a

series of heat exchange equipments which ultimately remove the heat to the outdoor atmosphere. This process involves

the application of chiller, water pump units and cooling tower as shown below.

According to the type of condenser used, the central air-conditioning system has air-cooled or water-cooled system. Air-

cooled and water-cooled systems are categorized by capacity and efficiency.

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Chilled Water System Schematic Layout

C SS C O O C CO O S S S S SO S C O S CO O S

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Air-cooled chilled water system

Air-cooled condenser: A type of condenser in which refrigerant flows through the tubes and rejects heat to air that is

drawn across the tubes.

Water-cooled condenser: A type of condenser that rejects the heat of the refrigerant to water flowing through it.

AHU: An air handler, or air handling unitoften abbreviated toAHU, is a device used to condition and circulate air as part

of HVACsystem. Usually, an air handler is a large metal box containing a blower, heating and/or cooling elements,filter

racks or chambers, sound attenuators, and dampers. Air handlers usually connect to ductworkthat distributes the

conditioned air through the building, and returns it to the AHU.

Fan-coil unit (FCU): A small terminal unit that is often composed of only a blower and a heating and/or cooling coil (heat

exchanger), as is often used in hotels, condominiums, or apartments.

Expansion tank: A component of a closed piping system that accommodates the expansion and contraction of the water

as temperature and, therefore, density, changes.Water-cooled chilled water system

Cooling tower: Cooling towers are heat rejection devices used to transfer process waste heat to the atmosphere. Cooling

towers may either use the evaporationof water to reject process heat and cool the working fluid to near the wet-bulb air

temperatureor rely solely on air to cool the working fluid to near the dry-bulb air temperature.

Condenser water pump unit: is a set of device by using mechanical forces to move the condenser water.

Chiller: A device that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. This cooled

liquid flows through pipes in a building and passes through coils in air handlers, fan-coil units, or other systems, cooling

and usually dehumidifying the air in the building. Chillers are of two types; air-cooled or water-cooled.

Air-cooled chillers are usually outside and consist of condenser coils cooled by fan-driven air.

Water-cooled chillers are usually inside a building, and heat from these chillers is carried by recirculating water to

outdoor cooling towers.

CLASSIFICATION OF HVAC CONTROL SYSTEMS SENSORS ACTUATORS AND CONTROLLERS
http://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Fan_(mechanical)http://en.wikipedia.org/wiki/Air_filterhttp://en.wikipedia.org/wiki/Damper_(architecture)http://en.wikipedia.org/wiki/Duct_(HVAC)http://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Wet-bulb_temperaturehttp://en.wikipedia.org/wiki/Wet-bulb_temperaturehttp://en.wikipedia.org/wiki/Dry-bulb_temperaturehttp://en.wikipedia.org/wiki/Dry-bulb_temperaturehttp://en.wikipedia.org/wiki/Dry-bulb_temperaturehttp://en.wikipedia.org/wiki/Dry-bulb_temperaturehttp://en.wikipedia.org/wiki/Wet-bulb_temperaturehttp://en.wikipedia.org/wiki/Wet-bulb_temperaturehttp://en.wikipedia.org/wiki/Wet-bulb_temperaturehttp://en.wikipedia.org/wiki/Wet-bulb_temperaturehttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Duct_(HVAC)http://en.wikipedia.org/wiki/Damper_(architecture)http://en.wikipedia.org/wiki/Air_filterhttp://en.wikipedia.org/wiki/Fan_(mechanical)http://en.wikipedia.org/wiki/HVAC

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Chiller Components

There are several types of water chillers. They differ from each other based on the refrigeration cycle or the type of

compressor they use.

Absorption water chillers make use of the absorption refrigeration cycleand do not have a mechanical compressor

involved in the refrigeration cycle.

Water chillers using the vapor-compression refrigeration cyclevary by the type of compressor used. Reciprocating

and scroll compressorsare typically used in small chillers. Helical-rotary (or screw) compressorsare typically used in

medium-sized chillers. Centrifugal compressorsare typically used in large chillers.


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Mechanical Room: Boilers, chillers, pumps, heat exchangers

Air Handling Units (AHUs): heat, cool, humidify, dehumidify, ventilate, filter and

distribute the air.

Room Controls: thermostats and Variable Air Volume (VAV) boxes


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Joe cool

Building Environment

Air Handling Unit

Fan

Chilled water

system

Htg & Clg Coils

Boiler

Hot water

system

Cooling

Tower

Chiller

supply air

distribution

system

EA

OA

RA

Air Handling Units


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37

Boiler

Chiller

Pictures from https://rfd-training.tac.com/docs/HVAC.pdf


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CENTRALISED AIR CONDITIONING


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VAV SYSTEMS

Air handler/Packaged Unit

buildingautomation

system (BAS)

VAVterminal

units

supplyductwork

returnductwork

supply-airdiffusers

Constant air

temperature off AC

Unit

Vary the air volume

as load requires


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VAV System Types

Changeover

Bypass(Varitrac)

True VAV

(Varitrane)Single Zone VAV

Used in Smaller buildingsseeking cost-effectivezone control

Simpler System ControlLess expensivethanVariTrane

Smaller Constant VolumeAHU/RTU (Typically15tons or less)

Up to 24 zonesPressure Dependen

Used in Larger Buildingsseeking idealoccupant comfort

Very Flexible System

Control (morecomplex sequences)

Larger Variable VolumeAHU/RTU equipment(up to 130 Tons)

Up to 120+ zones30% fan energy savings

over CVPressure Independent


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VAV System Types


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VAV System Types

EA

OA

RA

variable-speed drive

supplyfan

coolingcoil

thermostat

VAVbox

PA

SA


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NEW INVENTED TECHNOLOGY FOR AIR-CONDITIONING SYSTEM

DISTRICT COOLING

SYSTEM

CHILLED BEAM

SYSTEM


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C ASSIFICATION OF HVAC CONTRO SYST MS,S NSORS,ACTUATORS AN CONTRO RS


M-ARCH GENERAL HIET

INTELLIGENT BUILDINGS ASSIGNMENT


District Cooling Systems (DCS) is a system which distribute chilled water or other media, usually provided from a dedicated

cooling plant, to multiple buildings for air conditioning or other uses.

The Objectives :To centralized production of chilled water by using district cooling plant. The generated chilled water will then be channeled

to various building blocks thru pre-insulated seamless underground pipes.

DC means the centralized production and distribution of cooling energy. Chilled water is delivered via an underground

insulated pipeline to office, industrial and residential buildings to cool the indoor air of the buildings within a district.

Specially designed units in each building then use this water to lower the temperature of air passing through the buildings

ACS.

The output of one cooling plant is enoughto meet the cooling-energy demand of dozens of buildings. DC can be run on

electricity or natural gas, and can use either regular water or seawater. Along with electricity and water, DC constitute a new

form of energy service


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, ,


M-ARCH GENERAL HIET




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, ,


M-ARCH GENERAL HIET


DCS- APPLICATION IN MALAYSIA

PUTRAJAYA

KUALA LUMPUR

INTERNATIONAL AIRPORT

BANGSAR

UKM


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, ,


M-ARCH GENERAL HIET


CHILLED BEAM SYSTEM

It is a type of convection HVAC system designed to heat or cooled high rise building such as commercial building.

Its primarily gives off its cooling effect through convection by using water to remove heat from a room.

Pipes of water passed through the beam suspended short distance from the ceiling of a room.

As the beam chills the air around it, the air becomes denser and falls to the floor.It is replaced by warmer air moving up from below, causing a constant floe of convection and cooling the room.


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M-ARCH GENERAL HIET


SYSTEM

In many buildings there is a variety of spaces with different users and varying thermal loads.

These varying loads may be due to different inside uses of the spaces, or due to changes in cooling loads because the sun

shines into some spaces and not others. Thus simple system, which supplies a single source of heating or cooling, must be

modified to provide independent, variable cooling or heating to each space.

When a system is designed to provide independent control in different spaces, each space is called a zone. A zone may be

a separate room. A zone may also be part of a large space. For example, a theatre stage may be a zone, while the audience

seating area is a second zone in the same big space. Each has a different requirement for heating and cooling.

This need for zoning leads us to the four broad categories of air-conditioning systems, and consideration of how each can

provide zoned cooling and heating.

The four systems are

1. All-air systems

2. Air-and-water systems

3. All-water systems

4. Unitary, refrigeration-based systems


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M-ARCH GENERAL HIET


ALL-AIR SYSTEMS

All heating, cooling, and humidification is supplied to a space by the air

1. Single-duct systems

Constant volume

Multi-zone, variable-air volume (VAV)Multi-zone with re-heat

2. Dual-duct systems

R.A DUCT

S.A. DUCT

HEAT

R.A. DAMPER

COIL

E.A.

DAMPER

FILTER

O.A.

DAMPER

FRESH

OUTDOOR

AIR

EXHAUST

AIR

R.A. GRILL

COOL

AIR

S.A.

TERMINAL

S.A.

FAN

R.A.

FAN


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M-ARCH GENERAL HIET


ALL-AIR SYSTEMS

Five primary types of all-air systems are commonly encountered in new and existing buildings.

Single zone and multi-zone systems are constant volume, variable supply-temperature systems that are controlled at the

central air handler.

Terminal reheat and dual duct systems are constant volume, variable temperature systems that are terminally controlled -

- a control approach that increases system flexibility and adaptability.

The variable air volume system is a variable flow, constant temperature system with terminal control .

The dual duct and multi-zone systems are multiple path systems with two or more separate supply air ducts, while the

single zone, terminal reheat, and variable volume systems are single path systems with one common main supply duct.

Numerous variations and hybrids of these systems may be encountered.

SINGLE ZONE

A single zone system consists of an air handling unit. The integrated package is most commonly a rooftop unit, as access to

the exterior environment for heat rejection or combustion air is readily available.

In a single zone all-air HVAC system, one control device (most commonly a thermostat) located in the zone

controls the operation of the system.

The primary advantage of a single zone central system is its simplicity. Single zone systems are the most basic and least

complex of central all-air systems. Because of this simplicity, they are usually the lowestfirst-cost all-air system, the easiest

to maintain, and the simplest to design. The primary disadvantage of asingle zone system is that it can condition only one

zone.


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M-ARCH GENERAL HIET


ALL-AIR SYSTEMS

Multi-zone system

delivers conditioned air to several zones from a single, central air-handling unit.The zones served should have similar

thermal load requirements such as offices or classrooms. Condi-tions in each space are maintained by temperature

controllers in each zone, which vary the amount ofheated or cooled air to be delivered.AIR-AND-WATER SYSTEMS

Air-and-water systems condition spaces by distributing air and water

sources to terminal units installed in habitable spaces throughout a

building. The air and water are cooled or heated in central mechanical

equipment rooms.

The air supplied is called primary air; the water supplied is called

secondary water. Sometimes a separate electric heating coil is included

in lieu of a hot water coil. This chapter is concerned primarily with airand-water induction units, fan-coil units, and radiant panels as used in

air-water systems

Air-and-water systems apply primarily to exterior spaces of buildings

with high sensible loads and where close control of humidity is not

required.

They may, however, be applied to interior zones as well. These

systems work well in buildings such as office buildings, hospitals,hotels, schools, apartment buildings, and research laboratories


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ANEURINE MATHEWS, SATHYA ,VIDYA SAGAR

M-ARCH GENERAL HIET


Actuators :

An actuatoris a type of motorthat is responsible for moving or controlling a mechanism or

system.

It is operated by a source of energy, typically electric current, hydraulic fluidpressure,

or pneumaticpressure, and converts that energy into motion. An actuator is the

mechanism by which a control system acts upon an environment. The control system can

be simple (a fixed mechanical or electronic system), software-based (e.g. a printer driver,

robot control system), a human, or any other input.

For effective HVAC systems performance and improved energy efficiency, Johnson Controls

offers high quality HVAC products including pneumatic valve actuators. Each of our valve

actuator products is designed to work seamlessly within your overall HVAC system,

guaranteeing that your building remains energy efficient at all times.

http://en.wikipedia.org/wiki/Motorhttp://en.wikipedia.org/wiki/Hydraulic_fluidhttp://en.wikipedia.org/wiki/Pneumatichttp://en.wikipedia.org/wiki/Pneumatichttp://en.wikipedia.org/wiki/Hydraulic_fluidhttp://en.wikipedia.org/wiki/Motor

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M-ARCH GENERAL HIET


Dampers

A damperis a valve or plate that stops or regulates the flow of airinside

a duct, chimney, VAV box, air handler, or other air handling equipment. A damper may beused to cut off central air conditioning(heating or cooling) to an unused room, or to

regulate it for room-by-room temperatureand climate control. Its operation can be manual

or automatic. Manual dampers are turned by a handle on the outside of a duct. Automatic

dampers are used to regulate airflow constantly and are operated

by electricor pneumaticmotors, in turn controlled by athermostator building

automationsystem.

http://en.wikipedia.org/wiki/Airflowhttp://en.wikipedia.org/wiki/Duct_(HVAC)http://en.wikipedia.org/wiki/Chimneyhttp://en.wikipedia.org/wiki/Variable_air_volumehttp://en.wikipedia.org/wiki/Air_handlerhttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Climate_controlhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Pneumatic_motorhttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Pneumatic_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Climate_controlhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Air_handlerhttp://en.wikipedia.org/wiki/Variable_air_volumehttp://en.wikipedia.org/wiki/Chimneyhttp://en.wikipedia.org/wiki/Duct_(HVAC)http://en.wikipedia.org/wiki/Airflow

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HVAC Sensors

Sensors measure the controlled medium and provide a controller withinformation concerning changing conditions in an accurate and repeatable

manner. The common HVAC variables are temperature, pressure, flow rate

and relative humidity.

Controller

Controlled

Element

Controlled Variable = Space Temperature

Controlled Medium = Room Air

Controls

Heat/Cool Source

Control Agent


M-ARCH GENERAL HIET



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HVAC DUCTING

Ductwork Design Basics

HVAC duct systems deliver air from fan to diffusers, which distribute air to space Fan creates

a pressure difference which moves air Duct layout/sizing is related to this pressuredifference Goal: size ductwork to minimize pressure drops, while keeping costs

installation/material costs down.

Duct Sizing Concepts

Use even duct sizes (ex: 24/12) Branch ducts ideally

should be 2 shorter than duct main (ex: 12 deep

duct should have no more than 10 deep takeoff)

Exception: some fittings available for same size

takeoffs Internal duct insulation: 1 reduces 2 total

of ductwork dimensions Coordinate exposed

ductwork as it may be preferred to be round, spiral

and/or painted by client or architect. Keep ductaspect ratios less than 4:1. (Square or Round is ideal.)


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Rectangular duct Round duct w/ spiral seam

Flat oval duct Flexible duct

(Source: Wang, S. K., 2001. Handbook of Air Conditioning and Refrigeration)


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M-ARCH GENERAL HIET


Duct Construction

Shapes of air duct Rectangular

More easily fabricated on site, air leakage

Round

Less fluid resistance, better rigidity/strength

Flat oval

Flexible

Multiple-ply polyester film w/ metal wire or strips


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Ductwork Comparison

Round ductwork is the most efficient but requires

greater depth

Rectangular ductwork is the least efficient but can be

reduced in depth to accommodate smaller clearances

Avoid aspect ratios greater than 5:1


M-ARCH GENERAL HIET



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Duct Construction

Duct specification

Sheet gauge and thickness of duct material

Traverse joints & longitudinal seamreinforcements

Duct hangers & their spacing

Tapes & adhesive closures

Fire spread and smoke developed

Site-fabricated or factory-/pre-fabricated


M-ARCH GENERAL HIET



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Duct Construction

Duct heat gain or loss

Temperature rise or drop

Duct insulation (mounted or inner-lined) Reduce heat gain/loss, prevent condensation, sound

attentuation

Minimum & recommended thickness

See ASHRAE standard or local codes

Temperature rise curves

Depends on air velocity, duct dimensions & insulation


M-ARCH GENERAL HIET



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HVAC Air Distribution Equipments

4 Way Diffusers Two Way Diffusers One Way Diffuser

Round Diffusers


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M-ARCH GENERAL HIET


Return / Exhaust Grilles


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ARCHITECTURAL , AESTHETICAL TREATMENT FOR HVAC


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EXPOSED DUCTS TREATED


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FABRIC DUCTS AVAILABLE IN

COLORS


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FABRIC DUCT

NYLON DUCT


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RUSTIC LOOK TO THE INTERIORS


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OPEN CELL CEILING, RETURN IS TAKEN CARE IN THE OPEN

CELLS


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TOP HVAC BRANDS


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M-ARCH GENERAL HIET


The ASHRAE standards collection includes more than 4,000 standards pertaining to a

variety of topics such as:

Condensers and compressors

Airflow (outlets/inlets)Heat pumps

Refrigerators and freezers

Automatic ice makers

Proportion of oil in liquid refrigerants

Energy conservation

ASHRAE standards are used by designers, manufacturers and installers of heating, air

conditioning and refrigeration equipment. They are also used by architects and

mechanical engineers to specify equipment.


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ANEURINE MATHEWS SATHYA VIDYA SAGAR Sunmugham

Documents

2- Hvac Notes