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Heating Ventilation and Air Conditioning Full Course - HVAC Course (Part 13)

 This is part 13th of the full HVAC course. If you have missed the previous parts, you can access them from the end of this post.
                            Air conditioning systems are used to cool down your home or office space. They use refrigerants like R-22 and R-134a to accomplish this task. These substances are harmful to the environment, but they do not break down easily. This leads to a lot of environmental contamination, especially if they are disposed into landfills.
                            There are two types of air conditioners that exist today. One of them is split systems, meaning they have both heat pump and cooling compressor sections. Another type is called single-system units, or just units. These are devices that only have a cooling compressor section. Single-system units are much less common than split-system units.
                            Heat pumps run off electricity, whereas compressors run off natural gas. If a unit runs off the power, then it will require electricity, while compressors that run off natural gas will require propane or butane. Gas appliances are much cheaper than electric ones, which means that heat pumps are usually better suited for large spaces.
                A venturi tube is a piece of equipment that helps to regulate temperature and pressure. Most ducted systems have one installed at the return side of the furnace. They help to remove hot air from your room before it hits your cold air distribution coil.
                        Ductwork is the conduit through which your conditioned air travels. It can consist of metal, fiberglass, plastic, or some combination of these materials.
                    A variable frequency drive (VFD) regulates the speed of your fan motors. This allows your fans to turn faster or slower depending on the needs of your room or area.

Direct Expansion System (DX) :

A direct expanded type of air conditioner has its own advantages over a conventional one, mainly that its structure is simple and compact, which means less maintenance and easier operation. This is due to the fact that it uses an evaporator coil directly connected to a compressor, so it only needs to connect a fan to discharge heat into the room. The advantage of the DX air conditioner is that it does not require a condenser coil, so it is lighter, smaller, and consumes less electricity. However, it still needs to run at full capacity throughout the year, therefore, it is not suitable for residential applications.
                DX air conditioning systems are used extensively throughout the world for both residential and commercial purposes. They have several advantages over traditional refrigeration methods including increased efficiency, reduced energy consumption, and longer life expectancy.
                The design of the DX system is based on the use of ammonia rather than freon gases. Ammonia has always been considered a safe gas to work with and causes no damage to the ozone layer, unlike other greenhouse gasses. The system works by bringing heat from outside the building into the space inside the building that is being cooled off. This heat then raises the temperature of the ammonia which is pumped out of the unit and into the space that needs cooling. Once the temperature of the ammonia rises it condenses back down creating an extremely efficient way of cooling your home or business. There are many different types of DX systems available today ranging from small portable units to large industrial size models.

Applications :

dx air conditioning systems are used broadly in commercial applications and residential applications. They are used for cooling spaces like offices, homes, factories, warehouses, etc. There are two types of dx air conditioners. One type is split-type and another type is unit-type.

Split-type dx air conditioner works by using refrigerants to create cold airflow. This technique requires a lot of space because they have to use several evaporators and compressors. On the other hand, unit-type dx air conditioners work by producing low temperatures through direct contact heat exchange. These units do not require any separate compressor and can be easily attached to walls and windows.

Applications of dx air conditioning system include

*Commercial Applications

*Residential Applications

*Industrial Applications

Advantages of DX system:

You can control your indoor climate at any time - regardless of the outside temperature.

-It creates a comfortable environment that doesn't require a lot of energy.

-It's cost-effective. A DX Air Conditioner is about $100 less than a conventional central air conditioner.

-It's easy to install. No ductwork is necessary!

-It's low maintenance. Simply clean and oil the filter each month.

-It uses less power.

-It has no moving parts.

-It's quiet.

-It does not use Freon or ozone depleters.

-It works well in small rooms. 

-It has a low initial cost.

-Compact in size.

Disadvantages of DX system:

-DX Air-conditioning systems are not cheap. They cost about $500-$1000. This can make it difficult for some people to afford these units if they do not have at least that much money lying around.

-DX Air-Conditioning Systems aren't always efficient. An average unit may only cool your home down 5 degrees while a normal AC does this at 15 degrees.

-There are two types of fans used in the DX system; the first type is the variable speed fan. This fan has multiple speeds that can be adjusted to suit the needs of the user. However, this feature comes at a cost. In order to achieve different speeds, the motor must work harder. The other type of fan is the constant speed fan. This version does not have any adjustable settings which mean it runs at a constant speed. Constant speed fans are usually recommended if you want to keep your electricity consumption down.

-Also, DX systems require a little maintenance which can be costly. Maintenance includes replacing filters, cleaning coils and evaporators, and lubricating motors. When these parts start showing wear and tear, they need to be replaced immediately. If left untreated, the components may fail resulting in downtime.

-Finally, DX cooling units are noisy compared to window ACs. They can be heard through walls and windows.

Window AC system:

Window AC systems range from 0.75 TR to 3.0 TR.
Window air conditioning systems are ideal for both residential and commercial applications. They can provide cooling comfort while significantly reducing energy consumption.

Applications :

Window AC's are used for small rooms, shops, labor camps, etc.

Advantages :

Using a Window Air Conditioner (window AC) can help save energy costs in your home. You are able to use electricity that would otherwise go unused in the summer months. This type of air conditioning uses less power than other types of systems. Most models come with a built-in timer to automatically turn off the unit during night time hours. If you have multiple units in your home, this feature allows them to operate independently from each other. These units do not require ductwork or any other modifications to your house. They usually have higher efficiency ratings, but may cost slightly more. The size of these units differs depending upon the model you choose. Some smaller units tend to last longer than larger ones. Window ACs can be used to cool your entire family room, bedroom, or even your office space. This type of air conditioner works best if you live in a cold season climate. You should try to keep your blinds closed at night. This way the heat will not enter through your windows. If you have a small apartment, then installing two window ACs might be beneficial. In order to get the maximum benefit out of this device, it’s recommended that you clean both your window and the area around your A/C unit on a regular basis. Dirt buildup along the sides of the casing can reduce airflow and cause the unit to work harder. Ensure that you keep your channels clean. If you notice condensation build-up inside your house, then you may want to consider replacing your filter. This could prevent damage to your unit and ensure that you receive the most efficient performance possible. An additional advantage of having a window AC installed in your home is that they create a cooling effect on your ceiling. This means that indoor temperature is lowered while still allowing fresh outdoor air to enter your home. This helps to eliminate excess humidity. When you install a window AC, you are not only helping to lower your monthly utility bills, but you are also improving the comfort level of everyone inside your home.

Disadvantages :

Window AC systems are great for heating/cooling your home but they have some disadvantages that can make them not as effective as they could be. One disadvantage of using a window AC unit is that each time a fan pushes air through a vent, it has to fight against the outside air temperature. That means if the house is cold, then the fans may have to work harder than necessary to keep the room at a comfortable temperature.

Another disadvantage of window AC units is that they only heat/cool rooms where a window is open. They do not provide full-home coverage. This means if you leave your bedroom door closed while it's hot, it won't help cool down the entire room.

Split AC system :

The split-air conditioning system is a highly efficient way to cool your home. All that you need is to purchase a split-system unit and install it inside your house. If you have a large enough space, the unit can easily fit into any corner of your room. You will find this type of air conditioner much affordable than traditional central systems and you can enjoy its benefits without spending too much money.

Here are some pros and cons of using a split-system air conditioner.


• High efficiency - Most split-system units use less energy than other types of coolers. They typically run at about 90% efficiency. This means they consume less power than standard cooling systems while working just as well.

• Easy maintenance - Split systems require little or no upkeep. You can easily repair them yourself, making them perfect for homeowners who want easy access to their AC units.

• Quiet operation - Split systems provide a much quieter experience than central units. Their quiet operation makes them ideal for people who like to sleep late without having their night disturbed by noisy air conditioners.


There are many disadvantages of using a split air conditioner. One disadvantage is that if the compressor is located away from the return duct then moisture tends to condense on the cold side of the unit and drip down into the return duct. This is not good since it can cause mold growth and damage to the HVAC unit. Another disadvantage is that the split system requires two compressors. This leads to higher energy consumption and increased noise level. Thirdly, the split system doesn’t have any built-in cooling effect. In other words, it does not utilize the waste heat generated as part of its operation. Therefore, it is recommended that in order to save electricity and money, consider installing a whole-house mini-split system.

Cassette Type AC system :

Cassette Air Conditioning systems are used to cool a large space like a gymnasium or a warehouse. They are commonly seen in industrial buildings. A cassette unit can be operated either mechanically or electrically. In mechanical operation, the compressor is driven directly by the motor through a belt drive. This arrangement offers better efficiency than the electrical variants.

When using a cassette-type air conditioner, the refrigerant gas circulates inside the cabinet under pressure. As the temperature rises, the refrigerant gas expands and absorbs heat from the air in the room. After absorbing the heat, the compressed refrigerant is passed back into the evaporator where it releases heat into the air. Inside the evaporator, the liquid refrigerant undergoes a change into a vapor phase that is forced out of the evaporator via a fan coil or other means.

Some of the benefits of using a cassette-style air conditioning system include easy installation, lower maintenance cost, higher capacity, better energy performance, and quiet operation. But there are several disadvantages of using a cassette-style unit. One of them is that these units do not provide sufficient cooling power for spaces with high humidity levels.

Advantages :

1. Less maintenance costs

The first advantage of using cassette type air conditioning systems is that they are easy to maintain. Since cassettes only require cleaning once or twice in a year, compared to other types of air conditioningsystems, it saves money and time. This allows your business to keep running without making any major repairs.

2. Lower energy consumption

Another benefit of using cassette-type air conditioners is that they consume less power than their counterparts. Cassette units can easily save up to 30% of the power used by conventional compressors because they use less electricity.

3. Reliable performance

As previously stated, cassette air conditioner systems do not need regular maintenance. Their reliability makes these units perfect for businesses that operate 24/7. They can provide continuous cooling services without compromising the quality of the product.

Disadvantages :

1. Efficiency

Cassette Type Air Conditioners are generally less efficient than Window Units. They use higher amounts of power (watts) to achieve the same cooling effect. This can result in higher electricity bills. In addition, they cause noise pollution around your home. Also, unless you have the proper insulation in place, your house may heat up as well.

2. Noise Pollution

Cassette systems create lower sound levels than window units. However, if you have children or pets, this could be an issue for you.

3. Maintenance

Cassette systems require cleaning at least once per month. A filter change should be done according to the manufacturer’s instructions.

Package AC

1. Why do we need to use package air conditioning systems?

Package air conditioners are used in many homes to cool down their indoor spaces. They come in various sizes and shapes that can easily fit into your home without taking up much space. If you have ever visited a grocery store or shopping mall, chances are that these units are being installed as they are becoming more popular than traditional window systems.

2. What are some of the benefits of using package air conditioners?

There are several benefits to having package air conditioners compared to conventional window air conditioning systems. First off, these units usually take up less space in your house than other types of units. This means you won't have to worry about where to put them since they don't require any additional room. Another benefit of package air conditioners is that they work just like a window unit would but better. You can still enjoy natural sunlight while keeping the warmth out of your home. Package air conditioners also provide great value since they typically cost half as much as window models.

3. How does a package air conditioner work?

The basic working principle behind a package air conditioner involves the intake of heat from outside and then releasing it back through a fan. As the heat moves up and around the unit, it gets pulled towards the vent. Once inside, the warm air is pushed out through vents located at each end of the unit. Depending on what type of unit you buy, you may be able to control the direction of the fan. There are also different settings that allow you to vary how fast the fan turns. You can also regulate the temperature of the unit. Some fans are capable of cooling down an entire room while others only cool down part of a room.

Disadvantages :

1. It will not save energy - Package HVAC systems are less efficient than window/indoor units. They use much more energy to cool your home, especially if they have been installed improperly. In addition, they tend to leak cold air out in the summer and warm air in winter.

2. Poor airflow pattern - While some types of equipment may create better indoor environments, you cannot count on them to provide optimal comfort. Indoor air can be affected by other factors like humidity, ventilation rate, and temperature.

3. High maintenance costs - You'll pay high monthly fees for electricity, heating, water, and cleaning.

4. Noise pollution - There's no doubt that this type of heating and cooling system can produce lots of noise. This includes everything from the fans to the compressor motors.

5. Noisy neighbors - If you live in a multi-unit building, using a package unit means you're going to be sharing space with your neighbors who may have their own units and vents.

6. Expensive repairs - Packaged units require regular service and repair work. Also, some models aren't designed to last long term, meaning replacement parts could be hard to find.

Variable Refrigerant Volume (VRV) or Variable Refrigerant Flow (VRF) System :

Variable refrigeration (VRV) uses low pressure to extract heat from one location and transfer it to another. VRV can be used to create a cooling effect, but this concept has many other applications. When used for air conditioning, it works by creating a lower temperature around your home than outside. This causes your body to lose heat faster, keeping your indoor temperatures consistent year-round.

This system consists of two chambers separated by a barrier. Inside the first chamber are fans that blow chilled air into the second chamber where your home's interior is located. Heat is transferred through the wall separating the two chambers. The cold side of the barrier is connected to a compressor while the warm side is connected to a condenser coil.

The compressor compresses refrigerant gas causing it to change state. Once the gas changes to a liquid, it enters the condenser coil. The coils absorb heat from the room air passing over them and turn liquid back into gas. The compressed gas leaves the condenser and moves through a tube to the evaporator coil. There it absorbs heat from air flowing over the tubes. As the vapor travels down the tubes, it cools and becomes a liquid again. The liquid then flows through a valve, expands, and returns to the compressor where it begins the cycle anew.

A blower fan pushes air across the surface of the evaporator coil. Air passes through the coil absorbing heat from the liquid refrigerant and changing back to a gaseous state before entering the return duct. In this way, the air inside your house is cooled.

There are many advantages to utilizing this sort of framework. You save energy because you don't have to use an electric heater to keep your home comfortable. Additionally, you save money because buying electricity isn't necessary. Also, your home doesn't need any ductwork since everything is contained. Finally, the system is easy to install. All you'll need is some plumbing skills and a bit of time.
                    VRF (Variable Refrigerant Flow) Air Conditioning systems are a great way to improve efficiency and save energy by using less refrigerant than traditional central ACs. They offer many benefits including greater comfort, improved indoor environment quality, lower running costs, and increased durability. They can operate at higher efficiencies, due to their ability to use different amounts of refrigerant depending on cooling demand. They are also more environmentally friendly since they utilize much smaller amounts of Freon and thus release significantly less CO2 into our atmosphere.
                    This system consists of a number of air handling units (possibly up to 48) connected to a modular external condensing unit. In this system, there is one outdoor unit and multiple indoor units. Here, refrigerant flow is varied using either an inverted control variable speed compressor or multiple compressors of varying capacity in response to change cooling/heating requirements within air cooling space. 


1. VRF Air conditioning can help reduce energy usage by up to 70% depending on your climate conditions.

2. A VRF is a very efficient way of cooling down your bedroom area. This is because the temperature inside the room doesn’t rise too high due to the fact that air blows directly from outside into the room.

3. The efficiency at which the unit works helps ensure that you won’t have to worry about running out of electricity.

4. Most importantly, this type of air conditioner is designed to protect the environment. Since they use less electricity than conventional AC units, they don't emit harmful gases like carbon dioxide.

5. With these benefits, there's no doubt that a VRF is one of the best ways of keeping cool in the summer months.

6. Wastage of energy is less/negligible.

7. Individual temperature control is possible as per zone requirements.

8. It does not require a big size.

9. Uses the HFC category of refrigerants (ex R134a).


- In case of refrigerant leakage from any of the indoor units, the complete refrigerant will be released from the circuit. This will increase the maintenance cost and will cause a system failure.

- There is no fresh air option, except ductable indoors.

Applications of VRF system

The application of VRF (Variable Refrigerant Flow) air conditioning systems has been around for years. VRF systems are used extensively in refrigeration applications to cool large spaces like warehouses, factories, and commercial buildings. But did you know that they can also be applied to cooling individual rooms? In fact, this method has many advantages over traditional central air conditioners and is not only cost effective but also environmentally friendly and energy efficient.

VRFs operate much similar to conventional air conditioners except instead of using a single compressor to move refrigerant throughout the system, multiple compressors are used to send refrigerant through tubes to different locations. The amount of refrigerant sent to each location is controlled by a valve which allows a small amount of refrigerant to flow at any given time. The result of this design is that the room being cooled receives a cooling effect, while simultaneously the other areas remain relatively warm. This means that VRF air conditioning systems can be used to provide cooling without completely freezing your entire home!

In addition to its use in homes, VRF technology has been widely used in several industries including manufacturing, food processing, pharmaceuticals, and agriculture. These types of industrial environments require high-quality cooling solutions that are stable and reliable. VRF air conditioning systems have proven themselves in these industries and can help businesses overcome challenges associated with temperature control, saving them money as well as reducing their carbon footprint.

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