Building Services: Air Conditioning B.

Arch III semester V

 SESSION I

Building Services: Air Conditioning B. Arch III semester V

What is air conditioning?
Air conditioning is defined as a process which cools (or heats), cleans, circulates, freshens air
and controls its moisture content simultaneously.

OR

Air conditioning is the process by which the air in a space is modified to make it comfortable for
the occupants.

• Cooling is needed when the room air temperature rises above threshold of 27°C.

SITUATIONS MOST LIKELY TO REQUIRE AIR CONDITIONING ARE;

• Rooms subjects to high gains, such as south facing rooms especially those with large
areas of glazing.
• Rooms with high equipment densities such as computer rooms and offices which make
extensive use of IT.
• Rooms in which environment (temperature, dust or humidity) sensitive work is being carried
out such as operating theatres, laboratory and microprocessor manufacturing units.

•Thus the primary function of the air conditioning is cooling although all systems filter the air and
some also provide heating and adjustments to the humidity levels.

Building Services: Air Conditioning B. Arch III semester V

 What is Air-conditioning ?
 Air conditioning is defined as a process which cools (or heats), cleans, circulates,

freshens air and controls its moisture content simultaneously.

AIR-CONDITIONING

 It is a system for controlling the humidity, ventilation, and temperature in a building

or vehicle, typically to maintain a cool atmosphere in warm conditions.

 Air conditioning is the process by which the air is modified to make it comfortable
for the occupants.

The machine which do all above process is known as air-conditioners

Building Services: Air Conditioning B. Arch III semester V

HUMIDITY
• The presence of water or water vapour in the air is called as humidity. When the water is more,
there is a high amount of humidity in the air.

• Humidity indicates the likelihood of precipitation, dew, or fog. High humidity makes people feel
hotter outside in the summer because it reduces the effectiveness of sweating to cool the body
by reducing the evaporation of perspiration from the skin.

HEAT
Most often air-conditioning is also about removing heat. There are two types of heat:
-‘Sensible Heat’ is any heat that rises the temperature but not the moisture content of the
substance. This is our regular and familiar every day heat. Because it raises the temperature it
can be detected by the senses, and this in fact, is why it is called Sensible heat.

- ‘Latent Heat’ is the tricky one. When we talk of Latent Heat we mean’s Latent Heat of
Vapourisation’.

Building Services: Air Conditioning B. Arch III semester V

 •It is that heat required
to transform a liquid to
vapour. Take water for
example. Water can be
heated to its boiling
point of 100’c. If more
heat is added at this
point the temperature
of the water does not
increase. The water
continues to boil and
becomes steam. So
where does all the
heat go? Well, the
heat goes into
changing water into
the steam. The latent
heat of vaporization
in this instance is the
heat required to
change water from
liquid at 100’c to
vapour at the same
temperature.
Building Services: Air Conditioning B. Arch III semester V
•Latent heat plays as important part in Refrigeration and Air-conditioning. It explains the
principle of refrigeration and is also is a component of Heat Load, Human beings generate
Latent Heat by the way of moisture on their skin. This perspiration requires to be dried; therefore
a change of its state from liquid to vapour is required. Fresh air which is added into the air
system, very often brings plenty of moisture with it. Removal of this additional moisture
also involves latent heat removal.
•A portion of the air-conditioning heat load is therefore in the form of latent heat. For e.g
heat load in an office 10% of the air-conditioning heat load could be in the form of latent
heat. This goes up around 25% in a restaurant and around 33% in a movie theatre.

Building Services: Air Conditioning B. Arch III semester V

Heat Load Estimation
• In warm countries the primary aim of air-conditioning is to bring the temperature down
within the conditioned space.
• It is important to select the right air-conditioning equipment to do the job. A system that is too
large for the requirement would not only cost more, but also be a waste of capacity.
• On the other hand, a system with low capacity would not be able to satisfy the comfort needs
of the occupants.
• Further, being of low capacity, the system would have to run for a longer time thereby
being prone to abnormal wear and tear
• It stands to reason therefore, that in order to select the equipment of the right capacity,
one must know the quantity of heat that is to be removed from the conditioned space,
This ‘quantity of heat’ is calculated using certain formulas and the process is referred to
as Heat Load Estimation.
• The heat within the space comes from various sources both external and internal. The
sun brings in external heat into space through the walls, roofs and glazing.
• Fresh air brought into conditioned space from outside, contributes substantially to the heat
load.
• The internal heat comes from electrical equipment, machinery, lighting and from the
occupants themselves.
• Humans dissipate heat into the space and their perspiration adds to the humidity and
therefore to the latent heat.
• The quantum of heat added by the occupants depends on there level of activity.
• People at rest will contribute less heat load than those doing more physical activity.

Building Services: Air Conditioning B. Arch III semester V

 Air conditioner (AC) working principle
An air conditioner collects hot air from a given space,
processes it within itself with the help of a refrigerant and a
bunch of coils and then releases cool air into the same space
where the hot air had originally been collected. This is
essentially how all air conditioners work.

Compressor

Evaporation Condensation

Building Services: Air Conditioning B. Arch III semester V

 Components of Air Conditions

AC
outdoor indoor

compressor condenser evaporator

Building Services: Air Conditioning B. Arch III semester V

 1. Compressor: This increases the
pressure of the refrigerant so that it will
accept the maximum amount of heat
from the air.

2. Condenser: Coils that move heat to

or from the outside air.

3. Evaporator: Coils that move heat to or

from the air inside the home.

Building Services: Air Conditioning B. Arch III semester V

How is cooling made possible?
• The core concept to be understood is Evaporation. (spirit of doctors clinic)

•In the refrigeration cycle this principle is put to work by causing a liquid Refrigerant to
evaporate in a cooling coil. This refrigerant is a specially chosen substance which has
the property of evaporation at very low-temperatures. The cooling coil, in which the
refrigerant evaporates, is in contact with the air (or water in chilled water systems)
surrounding it, there by cooling that as well. Once cooled, this air is then directed to the
spaces which require cooling.

• The main equipment used to produce the cooling effects are.

The Compressor:
The Condenser:
The Evaporator (‘Cooling Coil’ to most of us):

Building Services: Air Conditioning B. Arch III semester V

The Compressor (1)
The heart of every air conditioner system- automotive air
conditioner, home window air conditioner, or central air
conditioner-is the compressor. Residential systems use a
hermetically sealed compressor unit. Hermetically sealed
compressors combine an electric motor and compressor in a
single unit. Automotive air conditioning systems use a radial
compressor powered by the car engine. The compressor takes
in low-pressure gas at its "Inlet," compresses it, and discharges
it as a high-pressure gas at its outlet.
Building Services: Air Conditioning B. Arch III semester V
The Condenser (2)
The condenser take in the high pressure gas, represented by the red dots in the drawing, and changes its
state to a liquid, represented by the solid red in the drawing. The change of state occurs when the
temperature of the refrigerant is 25 to 30 degrees higher than the ambient temperature. If the outside
temperature is 90 degrees, the change of state occurs when the refrigerant is between 105 and 120
degrees. The air flowing through the condenser cools the gas and causes it to change state from gas to
liquid, the condenser fan in a home air conditioner is powered by a small electric motor, in a car, it is the
same fan that forces air through the engine’s radiator.

The Dryer
The liquid refrigerant leaving the condenser passes through a "Dryer" on its way to the evaporator. A dryer
may be a stand-alone component as shown in this basic diagram, or it may be part of an accumulator/dryer
or receiver/dryer. Whatever configuration the dryer takes, it serves the same purpose removing water vapor
from the refrigerant. The dryer contains a desiccant that absorbs water. The dryer is the component that is
replaced every time the system is opened up for repairs.

The Expansion valve (4)

An expansion valve and an orifice tube work differently but they serve the same purpose. As the liquid
refrigerant passes through the metering device, its pressure drops from around 225 psi to about 70 psi. As
the pressure decreases, the temperature of the refrigerant drops from around 110 degrees to around 40
degrees. At 40 degrees Fahrenheit, refrigerants start to evaporate causes an even greater drop in
temperature. As warm air flows through the evaporator, the cold refrigerant gas absorbs heat. The heated
gas is returned to the compressor through the suction line represented by the blue dots.

Building Services: Air Conditioning B. Arch III semester V

Building Services: Air Conditioning B. Arch III semester V
 Car Air conditioner also works on to the same principle
Building Services: Air Conditioning B. Arch III semester V
How Air Conditioning Works
Based on the physical law that evaporation absorbs heat and condensation exudes heat, an air conditioning
system uses evaporation and condensation of a fluorocarbon material that is a gas at normal temperatures
to "move" heat from inside your home to the outside, like this:
Building Services: Air Conditioning B. Arch III semester V
 Points to be considered
while placing an Air
Conditioner

Session-II

Building Services: Air Conditioning B. Arch III semester V

 Points to be considered while placing an Air
Conditioner
Height of the ACs:
We know the fact that, the cool air tends to settle down while the hot air tends to
go up. So, we place the AC at a higher elevation to achieve this natural air cycle of air
flow.

Body Experiencing Airflow from Split AC

Body Experiencing Airflow from Window AC
The indoor AC unit of split AC projects out from the
wall surface in the room. So, we recommend
The AC air diffuser of window AC unit are at installing the AC unit at a height more than a
the centre of the unit. So, there is a straight human height to avoid any obstruction. But, we
flow of air from the AC unit. Therefore, the need cool air at a lower level than the human height.
ideal height to fix a window AC is at 3ft – Thus, the designers of AC have designed the split AC
4ft (0.9 -1.2m) from floor level. air diffuser in the bottom of the unit, giving us
the optimal air throw in a downward direction.

Building Services: Air Conditioning B. Arch III semester V

 Points to be considered while placing an Air
Conditioner
•Place an AC unit in the centre of room maintaining the symmetry of your room,
which is technically also correct, as it diffuses uniformly distributed air.

Avoid asymmetrical Location of

Prefer Locating AC in the
the Indoor Unit
Centre of the Room

Building Services: Air Conditioning B. Arch III semester V

 Points to be considered while placing an Air
Conditioner
AC units according to the window openings and furniture layout of the
room. For example, for a layout having an asymmetrical sitting arrangement,
we recommend planning home AC unit in the centre of the sitting arrangement.

AC Location Depends on Furniture Layout of the

Room
Building Services: Air Conditioning B. Arch III semester V
 Points to be considered while placing an Air Conditioner
•You want to place your air conditioner in an area where the natural air flow of the space
is going to work with the air conditioner not against it. In other words if your air
conditioner is facing an often used door than it has to work twice as hard each
time the door opens.

•Place your unit where the air flow can move about freely. In other words do not
install your unit behind a piece of furniture and don't block it with anything in front of it. It
is imperative that an air conditioning unit is able to have a free flow of air surrounding it.

•You need a power source so you will need to mount your AC where there is an
outlet. It is best NOT to run extension cords to your AC.

•In the room that the AC unit is going try room darkening drapes. You can also try sun
screens that can keep out 60-70% of the suns heat.

•If you are using a window unit a good way to get more out of your air conditioner by
simple placement is to put the unit in a shaded window or to build a shade for it if it
is placed in the sun. A window unit that is shaded can run 30% less electricity to cool
down a space compared to a unit that is placed in a sunny location.

• Make sure the unit is installed correctly and that there are no gaps around the
window when using a window AC unit
Building Services: Air Conditioning B. Arch III semester V
 A temperature maintained by an AC depends on many factors like

•The capacity of the AC

•The size of the room
•The location of the room
•Openings in the room & size of opening
•The location of an AC unit in the room
•The thickness of the walls, etc

Building Services: Air Conditioning B. Arch III semester V

 Selection of Air-conditioner
(calculation of tonnage capacity)

The term ‘ton’ is used in connection with heat load or capacity of the air-
conditioning equipment.

1 ton refrigeration equals to 12,000 Btu or 3000 K Cal.

For example :

Ton = Volume in cu.ft /1000

If room size is 10’ x 10’ & ht is also 10’

So,
Volume =10 x 10 x 10 =1000 cubic feet
Ton = 1000/1000
= 1 ton
Building Services: Air Conditioning B. Arch III semester V
 http://bluestarindia.com/ac-tonnage-calculator/toncalculator.asp

Building Services: Air Conditioning B. Arch III semester V

 SESSION III

Building Services: Air Conditioning B. Arch III semester V

 TYPES OF AIR-CONDITIONING SYSTEMS

Air-conditioning

Non-ducted system Ductable System

Window A.C. Split A.C. Centralised air system Partially centralised air/water system

Constant volume system Thermal re heat or fan coil system

Floor Mounted Wall Mounted Ceiling Mounted

Variable air volume (VAV)system Induction system

Dual duct System Chilled ceilings and displacement ventilation

Exposed type Hide-Away type Cassette type

Building Services: Air Conditioning B. Arch III semester V

Building Services: Air Conditioning B. Arch III semester V
- Non-ducted system (local comfort cooling system) is in those air conditioners that do not
use any air ducting to cool the conditioned space.
These systems are suitable where air throw is limited to around 4 metres and small spaces are
involved, it also cools the air in a room to bring its temperature down to acceptable levels. The
cooling equipment is located in the room itself.

-Window sill air-conditioning

-Split air-conditioning

1. Floor mounted
2. Wall mounted
3. Ceiling mounted
3.a Exposed type
3.b Hide-away type
3.c Cassette type

Building Services: Air Conditioning B. Arch III semester V

Window Air-conditioners
• These machines can be seen mounted in windows and therefore are also referred to as
‘Window Air-conditioners’.
• In Window Air-conditioners the compressor, condenser-fan, condenser and evaporator are all
enclosed in a single cabinet.
• The unit is to be installed in a wooden frame either in a window or in a hole in the wall.
• The air being blown through the condenser must pass freely through without restriction.
• These air-conditioners come in cooling capacities of 0.5, 0.75, 1, 1.5 and 2 tons, adequate for
a room between 5 and 20 sq.metres in size.
• Larger spaces may be handled by using multiple units of this type. While Window Air-
conditioners are economical and most convenient to install they could be noisy for some
applications.

Building Services: Air Conditioning B. Arch III semester V

Building Services: Air Conditioning B. Arch III semester V
Split Air-conditioners
• The Split Air-conditioner is split into two basic
components, the Indoor unit and the Outdoor unit.
•These two units are connected by refrigeration tubing and
electrical wires that can pass through a hole in the wall
barely 10 CMS in diameter.
• Because the relatively noisy components, such as the
compressor and condenser fan, are in the outdoor unit, the
conditioned space tends to be quiet.
• There are situations where it is not possible to mount a
window air-conditioner because of obstructions from neigh-
bouring walls or non availability of a suitable window.
• In such cases the Split Air-conditioner is used because
the outdoor unit can be mounted on the roof or on a ledge
some distance away from the room to be air-conditioned.
• Though Split Air-conditioners are more expensive than
the Window Mounted type they are preferred for there low
noise levels.
• The outdoor unit houses the compressor, condenser and
the condenser fan.
• The indoor unit consists of the evaporator (cooling coil)
and the evaporator blower. Since the noisier. Components
are outside the building the conditioned space is much
quieter.
Building Services: Air Conditioning B. Arch III semester V
 Split air conditioner is one of the most
popular home air cooling appliances at this
time. It is usually divided into two main
units that are indoor unit and outdoor unit
(compressor and condenser). Both are
connected with refrigerant pipes. The big
advantage of the split system is quieter,
particularly if we compare to free standing
units like portable air conditioners and
window air conditioning units.
Therefore, split ac systems are favorite
choice for rooms where the silent is so
valuable, such as office room, bedroom,
and so on

Like other home appliances, split air conditioners also require the proper maintenance to ensure
they keep working powerfully and efficiently and also helpful to make them last longer (more
durable). The high efficiency performance indicates the unit will not work harder and will not
consume the electric energy higher than it normal should be. The totally maintenance should be
done minimum two times a year (pre-season maintenance and storage maintenance). The other
factors that can influence the performance of the unit is the way on how you operate it daily and
the weather condition of your local area.

Building Services: Air Conditioning B. Arch III semester V

Types of Split Air-conditioners Indoor Units
While the outdoor units of split air-conditioners are all similar the
indoor units are available in different types to suit the needs of the
air-conditioned space. The types of indoor units are:
Floor mounted:
The indoor unit of this Air-conditioner is typically kept on the floor
against the Wall of the space to be air-conditioned. This type is
ideal for living rooms or office rooms where adequate floor space
is available. Since the air throw is from the top, the space above
the indoor unit must be free from obstructions.

Building Services: Air Conditioning B. Arch III semester V

 High Wall Mounted:
This unit is fixed to the wall at a height of about 2.5
metres usually below the false ceiling. The
controls are generally operated either by a corded
or cordless remote control unit, on the wall is
preferred for rooms having less floor space. This
model is widely used for domestic and commercial
applications.

Building Services: Air Conditioning B. Arch III semester V

Ceiling mounted:
Split air-conditioners are equipment designed to be suspended from
the main ceiling. They are available in three models'
Exposed
Hidden and
Cassette
A. Ceiling mounted (Exposed): These units are fixed directly to
the ceiling and are visible. The unit is similar to the Floor mounted
(exposed) type. They are easy to mount and are preferred in
commercial areas or offices that do not have a false ceiling.
B.Ceiling mounted(Hide-away): These units are also mounted at
the ceiling but are designed for being hidden. They are generally
concealed by a panelled box or false ceiling. These units are
suitable for commercial areas where the interior design requires the
air-conditioning equipment to be concealed so as not to interfere
with the aesthetics. You will find such units working in restaurants
and offices.
c. Ceiling mounted (Cassette Type): Cassette type indoor units
are mounted above the false ceiling in such a way that the outlet grill
of the units is flush with the bottom of the false ceiling. While the
other types of indoor units provide for condensate draining by
gravity the same is not possible for the cassette type. To overcome
this problem a small motorised pump is employed to drain out the
condensate.
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
• A Multi Split System Air Conditioning unit has an outdoor and multiple indoor units. A Multi Split
System Air Conditioner is versatile, clean, quiet and energy efficient. The indoor units can be
placed in many locations, they also allow for quiet operation and easy use.
• Multi Split Systems provided for cooling and heating all year round. They have also been
designed to be discrete to blend in with your home décor.
• Multi Split systems come with an individual controller to operate each indoor system allowing
for complete comfort with the flexibility to choose your own temperature in each room.

Building Services: Air Conditioning B. Arch III semester V

• Multi-split Systems comprise of multiple indoor units attached to a single outdoor unit.
Depending on the brand selected, limitations exist as to the number and capacity of the units
available.
• The benefits of multi-split systems include less space requirements outside, ideal for air
conditioning or heating more than one room and all the features of standard split system air
conditioners. The multi-split system can also be inverter driven
• Today, Inverter Multi-Split Systems can come in a variety of combinations and configurations.
For example, an inverter multi-split system can be designed for you with wall or floor mounted
indoor units, ceiling-cassettes or small hide-away ducted units all attached to the one outdoor
unit. Some models run on single phase power only and can run up to seven indoor units with a
single powerful outdoor unit.

Building Services: Air Conditioning B. Arch III semester V

Mounting of outdoor units
All types of split units are
connected to a box like
cabinet placed outside the
conditioned space. This
‘box' is the 'Outdoor Unit/
(ODU) through which the heat
from the conditioned space is
dissipated into the
atmosphere. If we look inside
the outdoor unit, we will find a
Compressor, a Finned-Coil
Condenser and the a Fan
Motor with a fan blade, used
for blowing or sucking air
through the finned coil. We
would also find some
electrical components and
cables.
The outdoor unit is typically
mounted on an external wall,
the roof, sunshade or skirting
around the building.
Building Services: Air Conditioning B. Arch III semester V
Drainage of condensed water
• When the air around the evaporator is cooled, the moisture in the air accumulates as water
under the evaporator.
• This happens because the cold air cannot hold as much water vapour as it held when it was
warmer, you experience the same phenomenon when a small puddle of" water accumulates
under a chilled glass of water.
• This water referred to as 'condensate' is collected in a pan under the evaporator and must be
removed from the conditioned space. Therefore, wherever indoor units are mounted, there must
be a gently sloping drain tube to carry {condensate water away from the room. If the water is not
drained properly it may collect in the drain pan until it overflows and drips into the room.}

Building Services: Air Conditioning B. Arch III semester V

Mounting, Safety and Serviceability
• When the unit is wall mounted, we must ensure that the wall to which the ODU support
framework is grouted, is structurally sound and is capable of supporting the load of the ODU.
• This applies to any other structure on which the ODU is mounted.
• We should also make sure that the ODU support frame work is properly designed, with a
catwalk to permit servicing and a safety railing must be provided around the structure.

Coastal installations
• Special care must be taken while installing ODUs on the seacoast. We must ensure that:
the condenser fan outlet is not facing the sea wind. This is done to reduce the risk of the fan not
running at all or losing speed while working against the wind the ODUs are not located near
ground level, close to the beach, since sand can clog the condenser coils care is taken to give
the supporting framework a good quality anti corrosive paint treatment the isolator switch and
electr/cr.1 components are properly protected from moisture

Building Services: Air Conditioning B. Arch III semester V

Building Services: Air Conditioning B. Arch III semester V
Installation practices for Air-cooled units

Copper Standards for Piping

• We know that the Indoor Unit (IDU) of any Split air-conditioners is connected with the Outdoor
unit through refrigerant piping.
• Most often imported copper pipe is used for this purpose.
• Soft Drawn Copper Tubing is used for single phase Non Ducted split air-conditioners.
• Hard Drawn L-Grade Cooper tubing is used for 3 phase Ducted Splits/Packaged units.

Building Services: Air Conditioning B. Arch III semester V

Length of interconnecting piping
• We must always ensure that the right distance is maintained between the IDU and ODU.
There are limits to the distance between them imposed by the equipment design. As the
distance between the units increases the following happens:
- The refrigerant pressure drops, resulting in decreased cooling capacity.
- The lubricating oil does not return to the compressor easily, leading to compressor
damage (it is a good idea to provide an oil trap every 3 meters or so on the suction
line.
- This helps to return the lubricant to the compressor along with the return gas.) and
- The extra refrigerant required by long tubing can lead to un-evaporated liquid
refrigerant flowing into the compressor thereby damaging it.

Building Services: Air Conditioning B. Arch III semester V

Refrigerant pipe insulation
• Refrigerant Piping carrying gas from evaporator (cooling coil) to the compressor is known as
Suction line and the piping carrying liquid refrigerant from the condenser to the evaporator is
known as Liquid line.
• The insulation requirement will depend on where the metering device, usually a capillary or a
expansion valve, is located.
• If the metering device is located in the ODU the Suction and liquid lines must be separately
insulated and a gap maintained between the two lines.
• If however the device is located in the IDU, the Suction and discharge lines must be insulated
together.

Building Services: Air Conditioning B. Arch III semester V

 SESSION IV

Building Services: Air Conditioning B. Arch III semester V

Building Services: Air Conditioning B. Arch III semester V
Ductable systems can be further subdivided into
1. partially centralized air or water system
2. Central air system.
Where large spaces are involved, multiple units are used to distribute the air. Alternatively in
order to distribute the air uniformly using less units, Ductable systems are preferred. The term
‘Ductable’ implies any air-conditioning systems suitable for ducting.

Centralised air system – all of the heating or cooling is carried out in a central air handling unit.
Room by room control of temperature is achieved using the following system:
- Constant volume system
- Variable air volume (VAV) systems
-Dual duct systems

Centralised air systems do not just provide heating or cooling but can filter, humidify the air as
required. The central plant is usually in a ground floor plant room or may be a packaged unit
situated on the roof top or on to the margins of the campus .

• They are service friendly because of easy accessibility.

• They can handle longer ducts by virtue of having more powerful fans.
• Large tonnages can be handled with less units by using 10LTR or 15LTR units.
• Interiors are clean and undisturbed since the machines are located in a separate plant room.

Building Services: Air Conditioning B. Arch III semester V

Central plants
- Central Plants are usually large air-conditioning plants assembled at the site. These plants are
used for big buildings such as hotels, theatres, hospitals, large office complexes and factories.
- They are designed for accurate control of all the parameters of comfort. As the name implies
the Plant is housed in a central location, usually in a plant room. This plant room could be in a
basement or adjacent to the building to be air-conditioned.
-Though the Central Plant can look quite complex with large compressors, pumps, gauges,
miles of piping, ducts and cables, the basic components are the same as smaller plants.
- Central Plants comprise Compressors, Condensers, Air-Handling Units, Water Chillers and
Cooling Towers.
-The main divisions are those that use Direct Central Expansion (DX) and Chilled Water.

Direct Expansion (DX) system:

-In this system, air is cooled and conditioned in the plant room.
-This created air is then pumped to various parts of the building.
-The air returning from the air-conditioned area is sucked through a coil-fin arrangement by a
fan.
-Reffrigerant inside the coil picks up heat from this air and evaporates.
-The cold air is then pumped back to the air-conditioned space.
-In DX plants the place where this heat exchange takes place is called an Air Handling Unit
(AHU).
-This type of system typically uses ducting passing through the structure to various parts of the
building to be conditioned.

Building Services: Air Conditioning B. Arch III semester V

Chilled Water System:
-Where Refrigerant and water interaction takes place the system is called a Chilled Water
System.
- The refrigerant in the shell (or tube, depending on the design) of a shell & tube heat
exchanger, evaporates by picking up the heat from the water which is in the other portion of the
heat exchanger.
- This chilled water, is then circulated to various water-air heat exchangers called Fan Coil
Units/Air Handling Units.
- The system is also preferred where multiple zones are to be cooled like a hotel or hospital.

Air & Water-cooled Systems

-In the air cooled system, the heat from the conditioned area' is transferred to the cold
refrigerant warming it up. This warm refrigerant then sheds the heat to the air outside in the Air
Cooled Condenser.
-In the water cooled system the heat from the conditioned area is transferred to the cold
refrigerant warming it up. This warm refrigerant transfers the heat to water in the Water Cooled
Condenser thereby warming the water. This warm water in turn transfers the heat to the
atmosphere through the cooling tower.

Building Services: Air Conditioning B. Arch III semester V

Partially centralised air/water systems
– a central air handling unit is used first to filter and then heat or cool an air stream. Final
adjustment of temperatures is carried out rising room based equipment.
System types are;
- Terminal reheat or fan coil systems
- Induction system
- Chilled ceilings and displacement ventilation.
-The indoor portion of these units are located above the false ceiling and connected to the
ducting.
- Consequently they do not occupy floor space.
- Currently in India they are available in 3, 5 &. 7.5 Ton capacities.
- Since the indoor unit is located above the false ceiling the space available limits the capacity to
7.5 Tons per unit.
- However, great care must be taken to select the location of the indoor units. Ideally, they must
be located in corridors, above lofts, etc., where accessibility is not a problem.
-shapes like cupboards and are typically placed in a small enclosure adjacent to the conditioned
area.
- Inside this 'cupboard' like enclosure is housed the Compressor, Evaporator and the Evaporator
blower.
- Though these units are typically used with ducting they can also be placed directly in the room
to be conditioned whereby the cooled air is thrown directly into die rooms without ducting.
- Currently in India these units come in capacities of 5, 7.5, 10, 15 and 20 Tons Machines.
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
These air-conditioners come in both the Air-cooled and the Water-cooled units
Water-cooled models
- Water-cooled units require water.
- This water is used to cool the refrigerant in the condenser.
- Water is pumped through the shell & tube condenses which is a part of the packaged unit.
- This water is then sent into a 'cooling tower' outside the air-conditioned room where the heat is
dissipated to the atmosphere.
- Water cooled units give higher capacity and are more power efficient due to lower operating
pressure.

Building Services: Air Conditioning B. Arch III semester V

 Air-cooled models
- Air-cooled models are especially suitable for places where water is scarce or of 'hard' quality,
or where there is no space for installing a cooling tower.
- The heat is removed by way of an air-cooled condenser with a fan blowing through it.
- This Condensing Unit is mounted outside the building on a sunshade or a terrace.

Building Services: Air Conditioning B. Arch III semester V

Air handling Units
-The Air Handling Unit (AHU) is a centrifugal type fan that pumps air.
- The fan is usually located in the Air Handler/ Water Coil Cabinet.
- Its purpose is to create a pressure differential so that the air from the conditioned space is
drawn to the unit.
- The air is passed through a filter first to remove dust particles and then over the cooling coils
or chilled, water tubes where the heat is rejected.
- This cooled and dehumidified air is then drawn into the suction side of the fan and discharged
back into the conditioned space.
- A damper arrangement in the suction side of the AHU is kept a little open to draw in fresh air.

-The typical AHU is a sheet steel cabinet which houses the Cooling Coil and the blower fan.
- The motor is mounted on the outside of the cabinet and drives the blower by a pulley-belt
arrangement.
- Depending on their application, AHUs vary in size from small/medium sized packaged units to
large walk-in models.

There are two types of AHUs, The‘ single skinned' and the 'double skinned' type.

Building Services: Air Conditioning B. Arch III semester V

-The 'single skinned' AHUs are widely used.
- They have a single layer cabinet and are usually placed inside an AHU room.
- It is advisable to insulate the room so that the air in the AHU does not pick up heat from the
outside warm air.
- Keeping the AHU in an insulated room also reduces the sound levels in the conditioned space.

Building Services: Air Conditioning B. Arch III semester V

-The 'double skinned' type has an inner cabinet and the outer cabinet. A layer of thermal
insulation is sandwiched between the two cabinets.
- Though these AHUs are more expensive than the single skinned type they have the following
advantages:
Because of the insulation, the cool air inside does not gain heat from the surrounding
air thereby improving the efficiency of the plant.
They are more silent because the thermal insulation also acts like an acoustic
insulation.
They do not 'sweat' on the outside and can be kept in the non-air-conditioned space
thereby saving on the cost of a separate plant/AHU room.

Building Services: Air Conditioning B. Arch III semester V

Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
 1. Warm air from the room is sucked in through a grille at the base of the
machine
2. The air flows over some chiller pipes through which a coolant fluid is
circulating. This part of the machine works just like the chiller cabinet in
a refrigerator. It cools down the incoming air and a dehumidifier removes
any excess moisture.
3. The air then flows over a heating element (similar to the one in a fan
heater). On a hot day, this part of the unit may be turned right up so the
HVAC works as a heater.
4. A fan at the top blasts the air back through another grille into the room. If
the heating element is turned down, the air re-entering the room is much
cooler, so the room gradually cools down.
5. Meanwhile, coolant (a volatile liquid that evaporates easily) flows through
the chiller pipes, turns from a cool liquid into a cool gas, and carries the
heat from inside the room to the outside of the building. Just like in a
refrigerator, the coolant flows through a compressor unit and some
condensing pipes and turns back into a cool liquid ready to cycle round the
loop again
6. What happens to the heat? In the unit outside the building, there are lots of
metal plates that dissipate the heat to the atmosphere. An electric fan blows
air past them to accelerate the process.
7. Over time, the heat inside the building gradually pumps away into the
outside air.

Building Services: Air Conditioning B. Arch III semester V

Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Ducted Rooftop Packaged Air Conditioning System Overview
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
 AC for CAR

Building Services: Air Conditioning B. Arch III semester V

Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Facts:
A furnace works to keep a home warm in the winter and plays a critical part in the
operation of an air conditioning system.
Furnaces produce heat through the combustion of natural gas in the furnace's burner.
The heat produced from this process then passes through a heat exchanger. Air from
your home's return air ducts is blown over the heat exchanger, thus warming the air.

The furnace's blower then blows the warmed air into the ductwork, which carries and
disperses the warmed air throughout the home.

During warmer months, the blower inside a furnace continues to circulate return air
throughout the home--only this time, the return air has been cooled by being blown over
the indoor coil portion of the home's split-system air conditioning system. The
evaporator coil is typically installed down strean of the furnace.

Building Services: Air Conditioning B. Arch III semester V

Benefits:

Indoor warmth any time it is required. Energy efficiency -The efficiency of a furnace can
be determined by its AFUE--or Annual Fuel Utilization Efficiency. The minimum efficiency
level for furnaces currently manufactured in the U.S. is 80% AFUE. A rating of "80%
AFUE" means that for every dollar you spend heating your home; 80 cents are actually
applied to the generation of warmth. Compared to many of the 60% AFUE furnaces in
older homes, 80% AFUE furnaces are a significant improvement. However, for enhanced
energy efficiency, you may wish to consider a 95% AFUE furnace, such as Goodman's
line of 95% AFUE Furnaces. Cleaner air - As your HVAC system draws air out of various
rooms in the house through return air ducts, the air is pulled through an air filter, which
removes airborne particles such as dust and lint. Sophisticated filters may remove
microscopic pollutants, as well. The filtered air is then routed to air supply ductwork that
carries it back to rooms. Whenever the HVAC system is running, this cycle repeats
continually, constantly filtering and cleaning the air in your home.
1. This cleaning process improves with the installation of a variable-speed furnace.
Variable-speed furnaces use variable-speed blowers, which shift between several
speeds. These furnaces will run longer at a low speed, which causes them to filter the
indoor air more frequently.
2. And remember - because the furnace plays an important role in the operation of the air
conditioner, its variable-speed blower helps maintain both a consistent indoor
temperature and improved air quality year-round.

Building Services: Air Conditioning B. Arch III semester V

Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Building Services: Air Conditioning B. Arch III semester V
Why is it important to service your air-conditioning and refrigeration system?

- Air-conditioning and refrigeration systems, like all mechanical equipment, are subject to wear
and tear.
- They lose efficiency and consume more power over time, unless you monitor and maintain
them regularly.
-Studies reveal that with regular tune-ups, a system will deliver up to 95% of its original
efficiency.
- This helps reduce operating and revamp costs, and also helps to save a lot on power.
- There is a prevailing misconception that you don’t need specialised skills to keep your
- Air-conditioning and refrigeration system in peak condition. Or that in the case of a breakdown,
any local AC repair man can step-in for troubleshooting.
- Nothing can be further from the truth. Most local technicians lack in-depth understanding of the
complex designs and circuitry that make up the innards of modern day air-conditioning and
refrigeration systems. Also, they are ill informed when it comes to indoor air quality, airside
management and energy efficiency. In addition to this, their lack of resources and infrastructure
can cause irreparable damage to your system.

Building Services: Air Conditioning B. Arch III semester V

 Thank U…………
Building Services: Air Conditioning B. Arch III semester V