What is HVAC? | Heating, Ventilation, and Air Conditioning | Meaning of HVAC

What Is an HVAC System?

HVAC stands for heating, ventilation, and air conditioning. HVAC uses a variety of technologies to control, replace, clean, cool, heat, and circulate the air humidity in an enclosed area.

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.

HVAC System

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.

The word ventilation or V in HVAC represents the process of exchanging or interchanging air in a specific area or room. 

Ventilation has the capacity to remove extreme humidity and unpleasant odors, maintain the air circulation in the room, introduce environmental air and stop indoor air from stagnating. There are following two major ventilation methods:

  1. Natural ventilation
  2. Mechanical or Force ventilation

The HVAC units are used in both commercial and residential areas. They provide ventilation and maintain pressure ratios between the specific areas. The process of transporting and expelling air from a specific area is called indoor air distribution.

How does HVAC work?

The HVAC system works on the basic working principle of heat transfer, fluid mechanics and thermodynamics.

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.

working of HVAC system

Firstly, HVAC performs the ventilation process. In this process, a source of fresh air intakes from outside the building.  

When the outdoor air is introduced into the HVAC system, it is sucked into the air handling unit from where the working starts. As the air draws into the air filters, they remove allergens, dust, dirt, and other contaminations from the air and convert it into contamination-free air.

The next process is to change air quality according to your requirements. The air cools or heats up (depends on your desire) to remove additional moisture. When the air is cleaned, fresh air is delivered into your building at your desired temperature.

For better understanding, watch the below given video:

Types of HVAC Systems

The HVAC system has the following major types:

  1. Heating and Cooling Split System
  2. Hybrid Split System
  3. Duct Free (Mini-Split) System
  4. Packaged Heating and Air

1) Heating and Cooling Split System

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:

  1. One for cooling
  2. 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.

Heating and Cooling Split Systems

These systems act as large air conditioners usually installed outside the building and operate in the summer.

This system also contains a heat pump installed in the basements or other storage areas. It heats the building by using gas. The hot air produced by the heater is distributed throughout the building by using an evaporator or fan.

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.

Advantages of Heating and Cooling Split System
  1. The split air conditioner has an easy installation because it doesn’t need ductwork.
  2. It has an easy and simple operation.
  3. This air conditioning system runs quietly and is best suitable for conference rooms, libraries, bedrooms, offices, and classrooms.
  4. These have easy maintenance.
  5. There are many types of split air conditioners that use less energy and have high work efficiency.
  6. These systems cool various building zones by splitting the zones into small parts.
  7. They have low maintenance and utility bill costs.
Disadvantages of Heating and Cooling Split System
  1. The heat and cooling split system is 30% to 40% more expensive than conventional air conditioners.
  2. 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.
  3. These systems are not best suitable, especially if you live in an apartment or high-rise building.
  4. 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.
  5. 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.

2) Hybrid Split System

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.

The 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. 

hybrid split system

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.

Advantages of Hybrid Split System
  1. This system saves energy because it can switch between oil and natural gas at a low cost.
  2. As long as the temperature is more than 40 degrees, the heat pump uses less fuel and produces a lot of energy.
  3. 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.
  4. These systems improve your comfort level.
  5. They have a quiet operation.
Disadvantages of Hybrid Split System
  1. They have complex installations.
  2. You need a specialist for the installation of these systems.

3) Duct Free (Mini-Split) System

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.

Mini-Split System

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.

Advantages Of Mini-Split System
  1. It has small size
  2. It has high flexibility
  3. This system has an easy installation than other types of HVAC equipment.
  4. It doesn’t have ducts. Therefore, it saves the energy that may lose associated with ductwork.
  5. It offers more flexible internal design options than other types.
Disadvantages Of Mini-Split System
  1. 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).
  2. This system requires a qualified installer for installation. Finding a qualified installer or service representative for the duct-free system may not be easy.
  3. Improper installation of this system can lead to short
  4. 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.

4) Packaged Heating and Air System

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.

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.

Packaged Heating and Air Split System

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.

Advantages of Packaged heating and air system 
  1. It has easy maintenance.
  2. It is a most efficient air condition system.
  3. These have small size.
  4. You can install it inside the building.
Disadvantages of Packaged heating and air system 
  1. These systems aren’t so powerful like other types of HVAC systems.
  2. They are less efficient than other options.

HVAC System Components

The HVAC system has the following major parts and design:

  1. Thermostat
  2. Heat Generator
  3. Heat Exchanger
  4. Blower
  5. Condenser Coil
  6. Compressor
  7. Evaporator Coil
  8. Air Ducts and Vents
  9. Split Units

components of HVAC, components of HVAC system

1) Thermostat

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.

2) Heat Generator

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.

3) Heat Exchanger

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.

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 odorless and colorless gas. CO may cause nausea, dizziness, headaches, and even death in high concentrations. Therefore, you must install a CO detector to monitor such leaks.

4) Blower

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.

5) Condenser Coil and Compressor

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 vapor liquid then enters the evaporator coil via an aluminum or copper tube. The fan increases the air amount that flows through the condenser coils and accelerates the condensation process.

6) Evaporator Coil

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.  

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 vapor or gas refrigerant. The hot refrigerant gas is then returned to the compressor, and the cycle is repeated.

7) Air Ducts and Vents

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.

8) Split Units

These components are the most commonly used components of the heat pump or air conditioning systems. The split units are placed outside the room.

What is an Air Conditioning?

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.

What is Ventilation?

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, odors, 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.

Types of Ventilations

This ventilation process can be done in two methods:

  1. Mechanical ventilation
  2. Natural ventilation

1) Natural Ventilation System

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.

2) Mechanical Ventilation System

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.

What is the full form of HVAC?

The full form of the HVAC is heating, ventilation, and air conditioning.

Working cycle of HVAC system

HVAC system works on the refrigeration cycle. A refrigeration cycle works in the following way:

Working cycle of HVAC system

  • First of all, the hot gas or vapor refrigerant enters the compressor. At the compressor inlet, the vapor refrigerant has low temperature and low pressure. As the vapor 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 vapor refrigerant is delivered into the condenser for condensing process.
  • As the compressed vapor refrigerant enters the condenser or condensing coils, the condenser extracts heat from the compressed vapor 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 vapor 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.

When the weather changes, you can install a switching valve in your system that can switch from heating in winter to cooling in summer. By the backflow of the refrigerant, the heat pump’s cooling cycle changes from heating to cooling and vice versa. In this way, you can heat and cool your home with a single device in the same way and with the same hardware.

How Much Does It Cost to Service an Air Conditioner?

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 the air condition system.

Average Cost$90
High Cost$210
Low Cost$70

FAQ Section

What is the installation cost of AC (Air conditioner)?

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.

What is HVAC meaning?

The HVAC represents heating, ventilation, and air conditioning. This system uses different technologies to maintain the humidity, temperature, and indoor air quality according to the requirements. 

What is HVAC used for?

The HVAC system uses to supply cooling and heating inside the building. These systems are most commonly installed in modern buildings.

What does AC maintenance include?

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

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:

  1. Ice build-up
  2. Dirty filters
  3. Dirty condenser coils
  4. Damaged or faulty condenser or air filters
  5. Leakage in the evaporator

What is 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:

  1. Air conditioning system type
  2. Available space for installation
  3. Size of the system
  4. Ventilation
  5. Ducts
  6. Efficiency of the system
  7. Cost of the system
  8. Required maintenance
  9. Safety requirements
  10. Service life of the system

What is the design of HVAC system?

HVAC system design is a subdiscipline of mechanical engineering, established on the principles of heat transfer principles, fluid mechanics, and thermodynamics. 

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