2. The heating, ventilation, and air conditioning (HVAC)
system is an integrated setup that can heat or cool the
atmospheric air while conditioning the air quality based on
requirements. The HVAC systems can be implemented for
tasks like cooling, heating, moisture control, dust removal,
and oxygen replenishment in an indoor location.
The HVAC systems produce and supply cooling and
heating to business and domestic buildings. HVAC systems
can be easily found everywhere, from a single-family house
to submarines residence, where these systems deliver an
environmentally friendly environment.
3. The popularity of these systems is increasing day by
day. One of the main reasons for their popularity is
their high efficiency and flexibility. They are popular
in new buildings because they use fresh outside air to
supply high-quality indoor air.
4. The HVAC system works on the basic working principle
of heat transfer, fluid, mechanics and thermo-
dynamics.
The objective of HVAC is not just to heat or cool the
room. Rather, it also helps to increase the quality of the
indoor air and provides comfort for the community of
the specific house. HVAC systems have different types,
but they all start with similar basic elements.
5. The HVAC system is an integrated mechanical setup that
involves several mechanical products as fundamental
components of the system. Although the HVAC systems can
be customized based on operational requirements, the list of
components remains the same. The following are
components of the HVAC system.
Air Return Setup
Air Filters
Electronic Heating Elements
Exhaust Outlet
Compressors
Blowers
Coil
6. The general working principle of an HVAC system is
described below.
To trigger the function of an HVAC system,
the air return setup is activated.
This air return setup acts as an entry
and exit point of a ventilation cycle,
which remains continuously active throughout the
operation of an HVAC system. The outside air is sucked
inside the room with the help of industrial axial fans,
and the inside air is pushed outside the room with the
help of an exhaust fan unit.
The air passes through the air filters during the intake phase
itself and dust and other bacterial matter are filtered out.
7. Further, one of the following two activities can be performed
under temperature control via an HVAC system.
Air Heating: If the heating of air is required, the heating unit
of the HVAC should be activated. The heating operation in
the HVAC setup makes use of electronic heating elements.
The heating element can be an electronic heater, induction
coil, thermostats, etc. The heating element generates a heated
region in the path of suction air, as the air passes through the
heated region it warms up. This way, warm air is injected
inside the room.
Air Cooling: The cooling unit is activated to cool the air. In the
cooling unit, the air is passed through a coil, which is a part of a
heat exchanger. The heat exchangers can be of shell and tube or
cross-flow coil type. The exchanger unit consists of a refrigerant,
which ejects the heat from suction
8. Air Cooling: The cooling unit is activated to cool the air. In the
cooling unit, the air is passed through a coil, which is a part of a
heat exchanger. The heat exchangers can be of shell and tube or
cross-flow coil type. The exchanger unit consists of a refrigerant,
which ejects the heat from suctionair, and only cooled air is injected
into the room. The cooling units are integrated with a compressor
which is responsible for liquefying the refrigerant.
9. The HVAC system has the following major types:
Heating and Cooling Split System
Hybrid Split System
Duct Free (Mini-Split) System
Packaged Heating and Air
10. The heat and the cooling split system is a most famous
type of HVAC equipment. As the name of this system
represents that it is split into two main units:
One for cooling
The second is for heating
The heating and cooling split unit is common because
it has both outdoor and indoor units that can be easily
identified. It has an external cooling system that uses a
coil, compressor, and refrigerant to cool the air and a
fan to expel hot air out of the building.
11. These systems act as large air conditioners
usually installed outside the building and
operate in the summer.
This system also has a conventional thermostat to
control and maintain the internal temperature of the
building at the required temperature. These heat and
cooling split systems are most suitable and popular
because they have no environmental factors or specific
requirements.
12. This system also has a conventional thermostat to
control and maintain the internal temperature of the
building at the required temperature. These heat and
cooling split systems are most suitable and popular
because they have no environmental factors or specific
requirements.
13. The split air conditioner has an easy installation because it
doesn’t need ductwork.
It has an easy and simple operation.
This air conditioning system runs quietly and is best
suitable for conference rooms, libraries, bedrooms, offices,
and classrooms.
These have easy maintenance.
There are many types of split air conditioners that use less
energy and have high work efficiency.
These systems cool various building zones by splitting the
zones into small parts.
They have low maintenance and utility bill costs.
14. The heat and cooling split system is 30% to 40% more expensive than
conventional air conditioners.
You will need a professional technician for the installation of these
systems to confirm the warranty validation and safety. It may be hard
for you to find a professional, or he may cost you high for its
installation.
These systems are not best suitable, especially if you live in an
apartment or high-rise building.
The internal parts of the split system have a very quiet operation, but
the external parts, such as the compressor unit makes high noise. This
can create problems if you have a residence in a highly-populated area.
The installation of the drainage system exterior of the room can attract
the attention of other people. If this system leaks, this may cause a
short circuit which may cause the death of someone.
15. This type of HVAC is a little bit different than the split
system. The hybrid split system is popular because it has
the capacity to reduce energy costs by using its hybrid-
electric heating system, which makes it special from other
HVAC systems.
16. TThe owner usually makes this important distinction
to distinguish these systems from other types of HVAC
systems.
The maximum homeowners choose them because
these systems are quieter, highly efficient, and have the
ability to switch quickly between gas power to electric
power.
They have traditional thermostats and ducts and
deliver all the advantages of the split systems. These
systems also offer additional options to save energy
and reduce electricity bills.
17. This system saves energy because it can switch
between oil and natural gas at a low cost.
As long as the temperature is more than 40 degrees,
the heat pump uses less fuel and produces a lot of
energy.
The heat & cooling system of the air conditioning
series integrates various parts of a hybrid air
conditioning system in one device. This way, you can
use a fully customizable split system that suits your
desired requirements.
These systems improve your comfort level.
They have a quiet operation.
18. They have complex installations.
You need a specialist for the installation of these
systems.
19. The mini-split systems have high upfront costs but offer
significant advantages for specific requirements and
applications. This is an independent unit installed in each
room and provides better independent control. They install
on indoor walls and are usually connected to exterior
compressors.
20. This type of HVAC unit has high costs. These units are
easy to install and can be controlled independently,
making them well suited for new buildings like
additions, garages, and other buildings.
These systems are also valuable for services like venues
and hotels because they give occupants control over
the temperature and condition.
21. It has small size
It has high flexibility
This system has an easy installation than other types of
HVAC equipment.
It doesn’t have ducts. Therefore, it saves the energy
that may lose associated with ductwork.
It offers more flexible internal design options than
other types.
22. The main disadvantage of the mini-split system is its
high cost. The cost of cooling capacity for such an air
conditioning system range from approximately $ 1,400
to $ 2,100 per ton (12,050 Btu / hour).
This system requires a qualified installer for
installation. Finding a qualified installer or service
representative for the duct-free system may not be
easy.
Improper installation of this system can lead to short
This system also has an air handling unit. You can’t
ignore the existence of this unit. Even if it is small, it is
large and cannot be hidden, so it can spoil the beauty
of the room.
23. The packaged heating and air system is a best option
than other types of HVAC systems. This system is a
closed heating and air device stored inside the
building. This system has the capacity to both heat
and cool the house.
24. It generally stores in the top floor or attic storage room
to heat or cool the building. It has a compact size
which makes it appropriate for tight spaces or areas. If
you can’t store it in the outdoor environment, you can
place it inside the building. It has a small size.
These types of HVAC systems have easy maintenance
and extreme efficiency. This heating system is not as
powerful as other types. These are most commonly
used in hot climates.
25. It has easy maintenance.
It is a most efficient air condition system.
These have small size.
You can install it inside the building.
26. These systems aren’t so powerful like other types of
HVAC systems.
They are less efficient than other options.
27. The HVAC system has the following major parts and
design:
Thermostat
Heat Generator
Heat Exchanger
Blower
Condenser Coil
Compressor
Evaporator Coil
Air Ducts and Vents
Split Units
28. The temperature sensors of the thermostat indicate
when the heating or air conditioning needs to be
switched on or off. Your home may have different
temperature control zones then each zone will need its
own thermostat.
This component of the HVAC equipment should be as
far away as possible from the area where the
temperature difference from the expected average
temperature of the room is concentrated.
29. • The heat generator or heat pump is an important
part of the HVAC system. The main objective of
the heat pump is to generate heat by extracting
fuel energy in a furnace (also called a combustion
chamber).
• The hot produced gas then adds heat to the air or
other fluids, which heats the air going into the
air-conditioned environment. An electric heater
may also use to warmth the conditioning air.
• There are many devices for generating heat, but a
furnace is the most commonly used heat
generator. Therefore, you must consider the
combustion efficiency for controlling the
environmental emission and resource
management of these HVAC parts.
30. The main objective of the heat exchanger is to transfer
heat from one fluid to another fluid. In the case of an
HVAC system, the heat exchanger absorbs the heat
generated by the heater (such as furnace or
combustion chamber) and transfers it to another fluid.
When it is necessary to regulate the temperature of the
air flowing through the heat exchanger, some control
devices turn on the furnace or other heating units.
In maximum cases, heat transfers directly to the cold
air in order to supply heat to the desired area.
31. Maximum heat exchangers burn fuel (such as petrol,
diesel, coal) as a power source, but it has many safety
concerns which need to be considered. This is because
the combustion of fuels emits NOx. Therefore, CO acts
as a vital product for Carbon combustion process.
Sometimes, a cracked heat exchanger may leak carbon
monoxide into the air flowing throughout the
particular area.
Carbon monoxide is an odourless and colourless gas.
CO may cause nausea, dizziness, headaches, and even
death in high concentrations. Therefore, you must
install a CO detector to monitor such leaks.
32. A blower or fan uses to force the air from the heat
exchanger into the air duct and delivers it to the desired
area. This component of the HVAC system is driven by
an electric motor. You can adjust the airflow by
changing the speed of the motor. This motor must have
a variable speed.
Variable speed electric fans gradually increase speed
and reduce noise when less air is needed.
The combustion process finishes when the blower
motor stops. As the heat exchanger produces hot air, the
blower motor extracts all of the hot air present in the
heat exchanger and duct system, transfers this hot air
into the room and waits for the next heating cycle
before the motor shuts down.
33. One of the key components of the HVAC system is a
condenser coil or compressor, which is usually found
outdoors. As the hot refrigerant gas is transported to
the compressor, it compresses the refrigerant gas and
increases its pressure and temperature.
The compressor extracts the heat of the gas and
releases this heat into the external environment, and
converts the gas refrigerant into liquid form. This
vapour liquid then enters the evaporator coil via an
aluminium or copper tube. The fan increases the air
amount that flows through the condenser coils and
accelerates the condensation process.
34. The main objective of the evaporator coils is to lower the
temperature of the compressed liquid refrigerant and
converts it into vapor form.
The evaporator coil is an indoor component of the air
conditioning system. It uses to collect the liquid refrigerant
from the compressor. It has a nozzle. This nozzle mixes
condensed liquid with the warm indoor air and increases
the evaporation process. The evaporation process starts as
the condensed liquid mixes with the warm air.
35. The fan of HVAC lets the warm air in the room flow by the
return duct to the evaporator. The room’s indoor hot air
transfers its heat to the sprayed refrigerant, cools down; after
that, it distributes to the specific areas via ducts.
When air passes by the cool evaporator coils, moist air
condenses on the coil and reduces the humidity or moisture.
As the air humidity level drops, the indoor air cools down,
and the cooling process becomes more efficient.
In this process, the liquid refrigerant extracts heat from the
indoor hot air and converts it into vapour or gas refrigerant.
The hot refrigerant gas is then returned to the compressor,
and the cycle is repeated.
36. Air ducts use to transfer or direct air to various parts of
the HVAC system. Proper installation of the ducts is
very important to deliver high-quality air to the
desired areas or rooms.
If your ducts have been leaked, they may generate high
noise during operation. Even if you have a damaged air
duct, the air can be filled with extreme moisture or
unpleasant smell.
The vents use to deliver air into the desired rooms or
areas. They are installed with an air filter to prevent
dust and small particles from going into the room. The
air filter can also install in another part of the ducting
system.
37. These components are the most commonly used
components of the heat pump or air conditioning
systems. The split units are placed outside the room.
38. An air conditioner or air conditioning system provides
controlled cooling or moisture for a specific area or room. Air-
conditioned houses also have closed windows because open
windows can interfere with systems that are designed to keep
indoor air conditions constant.
During the working of the air conditioner, the fresh air from the
environment is usually sucked through the air vents into the
mixed air chamber and mixes with the indoor exhaust air. The
mixed air then goes into an outdoor or indoor heat exchanger,
which lowers the air temperature.
As the air cools according to the requirements, the air directs
into the desired area. The proportion of return air from fresh air
can generally be controlled by adjusting the ventilation
openings. Generally, an outside air intake is approximately 10
percent of the total air intake.
39. The word V or Ventilation in HVAC represents to
exchanging air in a specific area. This process improves
indoor air quality by removing carbon dioxide, bacteria in
the air, smoke, dust, heat, odour's, moisture, other gases,
oxygenation replacement, and temperature control.
In simple words, Ventilation is a method of improving air
freshness, composition and quality by exchanging air
between an air-conditioned space and the outside to dilute
gaseous pollutants in the air.
This ventilation process can be done in two methods:
Mechanical ventilation
Natural ventilation
40. Natural ventilation is a most ventilation process
in maximum buildings. In natural ventilation, air
passes naturally by the vents, doors, windows, and
other natural airflow ways.
There is no use of fans or dust for the airflow. This
process of air exchange plays a vital role in
fulfilling the oxygen requirements for breathing
and removing excess indoor humidity, carbon
dioxide, and unpleasant odors.
41. The second ventilation method is mechanical ventilation.
As the name of this method represents that it uses
mechanical units (such as fans or ducts) to allow air to flow
inside and outside the building.
These systems don’t rely on the natural airflow by windows,
ceilings, or walls to maintain a good environment inside
the building. The mechanical ventilation system uses fans
and ducts to circulate fresh air in and out of the
building.
In the previous time, maximum buildings had natural
ventilation due to windows, ceilings, cracks in buildings,
and the closing and opening of the doors. Though, the
mechanical ventilation system is becoming a progressively
vital part of home HVAC systems because modern
buildings create more enclosed houses.
42. HVAC system works on the refrigeration cycle. A refrigeration cycle
works in the following way:
First of all, the hot gas or vapour refrigerant enters the compressor.
At the compressor inlet, the vapours refrigerant has low
temperature and low pressure. As the vapours enters the
compressor, it starts the compression process of the refrigerant. It
compresses the gaseous refrigerant up to desired pressure and
temperature. After the compression process, the high-pressure
compressed vapours refrigerant is delivered into the condenser for
condensing process.
43. As the compressed vapours refrigerant enters the condenser or
condensing coils, the condenser extracts heat from the
compressed vapours refrigerant, decreases its temperature, and
converts it into liquid form.
After condensing process, the liquid refrigerant enters
the expansion valve, which expands the liquid refrigerant. This
expansion process further lowers the pressure and temperature
of the refrigerant and cools it.
After passing through the expansion valve, the liquid refrigerant
enters the evaporator. As the refrigerant enters the evaporator, it
absorbs the heat of the indoor air and cools the indoor air. As the
liquid refrigerant extracts heat by the indoor air, it evaporates
and again converts into vapours refrigerant and goes back into
the compressor, from where the whole cycle repeats. The main
purpose of this process is to extract heat by the indoor air,
transfer it into the environment, and cool the room or specific
area.
44. The maintenance, repair, and service cost of AC vary
according to the area where you live and the type of
repair or service.
The average maintenance servicing costs of the AC
vary from $70 to $210 for one-time service. The service
cost of the whole HVAC system varies from $140 to
$550.
The below-given table represents the maintenance and
repair costs of th
e air condition system. Average Cost $90
High Cost $210
Low Cost $70
45. The installation cost of the air conditioning system varies
according to your residential area and type of brand. The
installation cost of AC varies from $3,400 to $7,600.
Is it necessary to service AC every year?
It is not compulsory to service your AC unit every year.
However, it is best to repair your system every year for the
best performance of your HVAC unit. In this way, you can
reduce the repair and maintenance costs of your AC unit.
46. The AC maintenance package mainly includes the following things
Duct inspection
Thermostat inspection
Cleaning and inspection of drain lines
Removal of the fan debris
Amp measurement
Lubricate all rotating components
Refrigerant check
Seal and belt inspection
Electrical diagnostic
Cleaning and replacement of the air filter
Inspection of the coil fins
Electrical control sequence inspection to ensure that you don’t have the
AC and heater on simultaneously
Cleaning of condenser coils
Evaporator coil airflow tests
47. When should I change my AC filters?
You must replace your AC filters every 30 days. This will
increase the efficiency of your system and indoor air
quality.
Why is my AC Running But not cooling?
There are many reasons due to that your AC is running,
but it is not producing cooling. Some of the most
common reasons for which your AC unit can’t produce
cooling are given below:
Ice build-up
Dirty filters
Dirty condenser coils
Damaged or faulty condenser or air filters
Leakage in the evaporator
48. What are the parts of HVAC system?
The HVAC system has a compressor, vents, air ducts, evaporator,
condenser coils, heat exchanger, and blower. These parts play a big role
in the working of the HVAC system.
What are important factors to consider in the overall designing of a
HVAC system?
Following are some major factors that you must consider in the HVAC
system design:
Air conditioning system type
Available space for installation
Size of the system
Ventilation
Ducts
Efficiency of the system
Cost of the system
Required maintenance
Safety requirements
Service life of the system
49. What is the design of HVAC system?
HVAC system design is a sub discipline of mechanical
engineering, established on the principles of heat transfer
principles, fluid mechanics, and thermodynamics.
50. Mechanical Room: chillier, 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
53. Components
Weather louvers: To prevent insects, leaves, dirt and rain from
entering
Silencer: To reduce noise caused by air circulation
Flow rate controller: Automated adjustment of volume of air
(night and day, pressure control)
Control damper: Fixed adjustment of volume of air
Heating unit: To heat the air to the proper temperature
Cooling unit /de humidifier: To cool the air to the required
temperature or to remove moisture from the air
Humidifier: To bring the air to the proper humidity, if too low
Filters: To eliminate particles of pre-determined dimensions
and/or micro-organisms
Ducts: To transport the air
54. Flow rate controller
Control damper
Humidifier
Cooling battery
Filters
Ducts
Blocked
Poorly adjusted, bad pressure differential system
Bad water/steam quality/poor drainage
No elimination of condensed water/poor drainage
Incorrect retention rate/damaged/badly installed
Inappropriate material/internal insulatorleaking
