An Air conditioner is no longer considered as a luxury good in India. Although it’s taxed as such. There is healthy growth in the number of Air conditioners sold in the Indian market due to the rising heat and climate changes. Now that you are here, you surely are looking forward to buying an AC. But there are so many AC brands with so many different models in the Indian market which makes it confusing, especially for the first-time buyer. However, we suggest you not to buy any random air conditioner, because an appliance like this would stay for about 8-10 years in your home or office.

Indian Science got in touch with AC experts in the country, had interviews with technicians, researched 77 different air conditioners, bought around 24 air conditioners, chose the 11 best and reviewed them in the time period of 31 days and then gathered all data and came up with detailed reviews of the 11 Best air conditioners in India. While, the salespeople in the local showroom were busy throwing phrases such as Auto Clean, Copper Compressor Dual Inverter Compressor, we actually have explained all of them in our buyer’s guide.

Daikin, a known AC brand in India’s MD and CEO Kanwaljeet Jawa predicts 14-15% growth in the AC market in India during 2019-2020. The growth rate will be similar to that of 2016 which has seen double-digit growth due to a hotter than usual climate. So, it’s not just you who is feeling the heat.

The LG KS-Q18 is a split AC with an Inverter type compressor which can cool rooms up to 150 sq ft quickly and efficiently.

The LG KS-Q18 is a split AC with an Inverter type compressor which can cool rooms up to 150 sq ft quickly and efficiently.

The outdoor unit has a dual rotary compressor that works fast and consumes energy. LG has created the patented Ocean Black anti-corrosive treatment especially for Indian conditions of high heat, salinity, and pollution to protect the coils against rusting.

The device operates using a four-step energy control system that maintains it at between 40% and 80% of its operating capacity and results in significant savings of electric bills. The indoor noise level is 31 decibels which means it is only as loud as a whisper.

The product has a 1-year warranty on all the components and 10 years warranty on the compressor including gas refill. There is a warning system that indicates low levels of gas. Power consumption of 836 units (KWH) annually means just an average of 2.3 units (of course more during summer and nil in winter). That keeps your home cool at little cost.

The air conditioner also has a dehumidifier to make the humid monsoon season more bearable. In our tests, it was able to reduce 90% relative humidity to a comfy 70% with this function. You’ll also love the new Himalayan Cool technology which actually makes the AC cool the place very quickly.

It may be that your room is smaller and you don’t need a 1.5 tons air conditioner. With exactly the same technology you can avail of LG 1 Ton 5 Star Inverter Split AC (Copper, KS-Q12FNZD, Floral White). It has identical tech specifications but consumes 572 units per year. It is also an ideal model for small areas like doctors’ chamber and small shops.

Daikin’s FTKF series has unmatched performance, though it is a little pricey.  The air conditioner has a Power Chill feature which allows it to run at full for half an hour to cool a room down and then revert to a more energy-saving mode.

This means a few minutes after you turn it on, the room is full of cool air. In our tests, it cooled down a full-size room inside 10 minutes from the ambient 36° C to 27°.

The optimized 3D airflow allows it to throw air both vertically and horizontally and cool every nook and cranny. We found our thermometer reading the same in every corner of the room. With a consumption of 767 units every year it is far cheaper to operate than most units made even 3 years ago. That is not even 2 units per day making it remarkably economical (and a good way to recoup the slight extra that it costs).

We tested the sound level and found it to be faintly noisier than usual at 41 dB. But that is not enough to disturb anyone in the room.

You could also opt for the Daikin 1.5 Ton 4 Star Inverter Split AC (Copper, FTKP50TV, White). With a 4 Star rating, it consumes little more electricity but is far cheaper. If budget is your concern but you want to opt for the matchless quality of Daikin this is a suitable choice.

Daikin uses the latest R32 refrigerant gas which is environment-friendly and makes sure that you do not contribute to global warming while staying cool.

The Hitachi 5100X RSB5 is a split air conditioner that employs superior technology to provide you the best cooling solution possible. The inverter AC has wide-angle deflection mechanism that spreads cooled air far and wide across all of 150 sq ft.

Copper condenser coils allow maximum energy efficiency and this reflects in its low power consumption. Hitachi has always been at the forefront of innovative technological solutions and this shows in its grooved condenser coil design. The modification allows the increase of surface area without adding to either the size of the machine or its price.

Use of Tropical Inverter Technology allows the unit to function well in the searing summer that Indian cities face. A convenient On/Off timer allows the AC to be turned off automatically at night after the room has cooled down enough.

Our test unit performed admirably and was able to provide uniform cooling. R410A gas is not as modern as R32 due to its greater global warming potential but it has zero effect on the ozone layer. There is no noticeable difference between the two when it comes to performance.

An excellent alternative to this model is the smaller but equally advanced Hitachi 1.0 Ton 3 Star Inverter Split AC (Copper, MERAI 3100s RSF312HBEA White). Through rated at 3 Star it is very affordable and works fine in confined spaces. The remote control has a backlight so you can operate it in the dark without turning on your bedside lamp. What can be more convenient when you are feeling sleepy?

Blue Star is the most well known Indian brand when it comes to air conditioners and the product does not disappoint. Loaded with the latest features it gives the Japanese and Korean models a  run for their money.

The dual rotor compressor is extremely efficient at cooling without sky-high utility bills. The air intake incorporates no less than seven filters to remove all dust and suspended particulate matter. Due to high SPM in most Indian metros, this is a very worthwhile feature.

The biggest USP is the revolutionary iFeel technology that is used. There is a temperature sensor in the remote control that can sense if any part of the room is warmer. Most air conditioners have only one sensor inside the unit and none on the remote.

Even after you switch it off the blower will continue to run for a little while, and this allows the coils to dry and removes the possibility of rusting. Not only that, but a sleep mode is present which ensures a sufficiently cool but not cold room through the night.

With the help of a self-diagnosis tool, the AC immediately alerts you about any fault in its operation. The presence of error codes makes it easy for the technician to figure out the problem.

We found it to be the most convenient air conditioning unit since it is user-friendly and easy to operate.

If a 1.5 tonner is too big for your needs then, by all means, opt for a Blue Star 1.25 Ton 3 Star Inverter Split AC (Copper, IC315AATU, White) with the same impeccable performance. With a 10 years compressor warranty, it is probably the cheapest air conditioner to operate.

Voltas is owned by the Tatas and as expected has made superb air conditioners for over half a century.  The latest 185V JZJ is no different and shows why Voltas sells the largest number of air conditioners in India.

Voltas claims that it cools even at 52°C external temperature. A few years back such a claim would have been unnecessary but with parts of Delhi reaching 48°C in early June it seems that Voltas is set to become a bestseller.

In our tests, the AC quickly cooled a room of 150 sq ft in about 5 minutes but the sole drawback we found was the noise. It is not a very quiet machine and there is a steady drone in the background. However, this noise is due to a very powerful blower that helps in cooling quickly and reducing the blower speed would fix the problem for most.

The two-stage compressor would make your room feel cool and comfortable at very little cost. The inbuilt air purifier provides a welcome relief from the heat and dust of the Indian plains. The remote control has buttons that glow and is easy to use at night. Dehumidifier comes in handy at monsoon time and keeps your room dry.

Installation is easy and the technical support is quite good. The price of the machine is quite reasonable when you take into account the reputation of the manufacturer. The unit is by no means flimsy but made with high-grade plastic.

Many find it unnecessary to buy a 1.5 ton AC. For them the Voltas 1 ton 5 Star 125VCrown Inverter AC is excellent. It is easily able to withstand wide fluctuation of voltage from 130-270 volts and can be used without a stabilizer.

The brand new ESKO NEO model from Carrier is an extraordinary split AC with inverter compressor. With a capacity of 1.5 tons but incurring low energy expenditure, it does not burn a hole in your pocket to run this air conditioner.

The Flexicool Technology that Carrier has used allows the deployment of four modes of cooling – free running, hot, moderate, and comfortable. The AC is capable of automatically adjusting the cooling based on the requirement.

There is an innovative Sleep Mode that allows the temperature to rise by 1°C for the first two hours and after 8 hours the AC will be automatically switched off.

There is also a gas leak detector that switches off the machine and displays an error code. Carrier claims that it operates smoothly even at 55°C and that is going to come in handy in India.

The compressor has a new design called HYBRIDJET that gives fast and efficient cooling. In our tests, the ESKO NEO performed remarkably well and cooled the room evenly without any residual pockets of warm air.

The air purifier and dehumidifier are also well designed and deliver pure and clean air with the touch of a button.

With a Carrier installed you can forget fretting all through the summer and look forward to relaxing in your home and office at the optimal temperature all day long.

If you wish for something smaller, Carrier offers the Superia Plus Inverter Split AC (1 Ton, White, Copper). With only 660 units of annual energy consumption feel energetic no matter what season it is outside.

Amazon’s in-house brand is priced very reasonably but that does not mean it does not work well. As a value for money machine, it is suitable if you are on a tight budget and willing to forego an MNC brand name and logo for functionality and some great features.

We were quite taken aback by the way this AC performed. Frankly, we had expected Amazon had not put in time and effort into its home brand especially in a white goods category product that is as complicated as an AC.

But it is amply clear that Amazon has done its research well and sourced it from vendors who are capable of supplying quality at low cost. The biggest surprise is a filtration system capable of trapping particles as small as 0.3 µm!

The machine is equipped with an ingenious energy saver mode that allows it to automatically lowers output if the requirement is less. Sleep Mode lets the AC maintain a comfortable temperature at night but not cool the room too much. Amazon has focused on making the operation as affordable as possible to reach a broad segment of customers.

You will also find all the advanced features of far more expensive air conditioners such as latest anti-corrosion coating and self-diagnosis. Moreover, the functioning of the AC is almost noiseless and unless someone told you there would be no way to know it is not made by a highly reputed manufacturer.

Amazon offers an even cheaper model (if that is even possible) with the AmazonBasics 1 Ton 3 Star Inverter Split AC. At a price less than that of a usual 3 Star Window AC you get the latest new design features with an annual consumption of only 700 units of electricity.

LG is one of the most reputed names when it comes to consumer durables in India. The products from this Korean giant have been well received over the last two decades.

There is no need to think that a 3 Star machine is outdated. With its proprietary Ocean Black anti-corrosion protection, LG Q18YNXA can withstand the hazards of a tropical and humid country.

The novel Himalaya Cool technology drives the AC with enough power to cool your room almost instantly.

The four-step energy saver mode can provide over 50% energy savings making it the finest 3 Star AC in the market. With an auto-clean feature which keeps the insides of the unit free from fungus and bacteria, you can be sure that the air you breathe is pathogen-free.

Besides, the air purifier system works just fine and provides clean and crisp air all through the room and cools all the corners uniformly.

The real clincher is that you get a 10-year warranty on the compressor inclusive of gas recharge. With the auto restart, there is no need to reset the parameters due to a power cut. The air conditioner remembers the previous settings and works as before. Copper condenser coils are highly efficient at acting as a heat exchanger and the result is very affordable running.

The best part is that LG air conditioners provide hassle-free operation for years and helps you to combat the heat without any effort. If you feel this unit is too large for your needs, why not opt for the LG 1.0 Ton 5 Star Inverter Split AC (Copper, JS-Q12HUZD, White). Requiring only 1100 watts, it is a good cooling solution for small rooms and shops.

Hitachi is a brand name that is associated with quality engineering. From this trusted brand we review another inverter AC, the RSD31.

The use of Hitachi ACs has grown since they have successfully demonstrated that they are highly economical to own and operate. Durability is one of the chief concerns of a buyer and it is here that Hitachi has scored over probably every other brand.

No one wants to buy an AC with half of a month’s salary only to find after three months that it has knocked out. With R410A refrigerant you can be sure that the air conditioner will deliver consistent cooling year after year across at least 150 sq ft of space.

The other worry that buyers have is of technological obsolescence. Hitachi makes its machines future proof by providing them with all possible features that other brands do not even think of including. That is why the antifungal multistage filtration system that makes the air clean and pure is only to be found in a Hitachi.

Do not be fooled by the 3 Star tag. The Air conditioner which is 5-star today will be 3-star within 20 months. So this machine was the most advanced cooling system when it first came in the market.

If your needs are satisfied by a smaller unit, go for the Hitachi 1.0 Ton 3 Star Split AC (Copper, RIDAA 3100f RSG312HBD White). A smaller sized air conditioner that packs a punch at a reasonable and affordable price it is well suited for your second bedroom or dining area.

The other Korean giant in India is well known for its premium smartphones and televisions. Its innovative streak extends to manufacture of air conditioners too.

This is amply displayed by the 8-pole digital inverter compressor that consumes far less power than other brands. Not only that but it has aluminum alloy condenser coils for the most efficient working.

When you combine this with features such as Durafin heat exchanger you surely have a winner.  You can even switch it to single user mode which operates it at lighter load and reduces bills. Samsung products are well known for their novel ideas and the air conditioner did not disappoint us during tests.

The ease of use increases when you consider the inbuilt voltage stabilizer that allows it to work from 146-290 volts without any hitch. There is a special controller circuit that prevents power surges from affecting the compressor.

Unlike most of the air conditioners, we have discussed above it can not only cool but also heat a room in winter. The advanced 8 pole compressor does not have to switch on and off but changes speed to adjust to the needs. This prevents wear and tear and extends the life of the unit.

A fast cool mode makes the compressor cool a room in a few minutes and then steps down operation to normal mode.

Maybe you need something smaller for your home. Then you can install the Samsung 1 Ton 3 Star Inverter Split AC (Copper, AR12NV3HFTRNNA, Starflower). With a 10 year warranty on the compressor, it can cool rooms up to 110 sq ft in size in no time.

Whisper silent cooling will be your first impression of the LG JS-Q18. The inverter compressor with GoldFin condenser coils is able to give a cooling experience that you can hardly imagine.

Combined with the Himalaya Cool mode it will cool down any room to 25°C in minutes. In our tests, we found that rather large areas were often not cooled by other brands but the LG is consistent at cooling all the nooks and crannies.

The use of the proprietary 3M filter keeps dust and SPM at bay and lets you breathe in pollution-free air. Meanwhile, the unit stays corrosion free with Ocean Black anti-rust treatment over the coils.

LG has for long been the leader in this industry and that has received another boost due to its reliance on copper coils that are very suitable for heat exchange. They are a little more expensive but the company has never relented on performance.

An inbuilt stabilizer keeps the circuits safe from power surges and you can go to sleep at night knowing that it will not be harmed by thunder and lightning.

A nine-year warranty on compressor further demonstrates the confidence the company has in the performance of this machine. This is the reason why LG is the leading name in cooling solutions be it refrigerators or air conditioners.

But will you like something smaller? Then LG has the perfect product for you – LG 1 Ton 3 Star Inverter Split AC (Copper, KS-Q12YNXA, White). It requires only 685 units annually and will be a perfect fit for your small office or guest bedroom.

You don’t want to buy an AC from a company which can’t provide service in your area or can’t help you when there’s an issue with the unit. After doing crazy research and calling almost 15 brands from more than 340 cities from 24 different states which took more than 173 hours, we’ve made the list of the brands which are best across the entire country.

If you are looking to buy a new AC or you are a first time AC buyer it is important that you have a clear idea of the brands, and what they have to offer. The cooling equipment hash vastly changed in the last few years as more and more stringent energy efficiency criteria have been adopted.

An air conditioner is no longer something that guzzles electricity but most of them consume within 600 and 1100 units annually or at most an excess annual bill of Rs. 10,000 for normal use of 6-8 hours daily.

Several manufacturers are offering their product and we have chosen to highlight the finest and those who are well known due to their quality, reach, technology and reliability.

Daikin from Japan is a specialized cooling solutions manufacturer. That means their research efforts are not spread thin across many different types of white goods but focused on Air Conditioners.

The USP of this well-regarded brand is that they bring in the most advanced technologies that are soon adopted by other brands. Take for example the Econo Mode using which Daikin air conditioners can detect the power being drawn by other appliances such as hair-dryer and washing machine and adjusts its consumption accordingly.

Daikin ACs also have the new Coanda Airflow System which does not simply throw out cold air but guides it above and allows it to spread evenly through the room.

We have been acquainted with the LG brand in India since the mid-90s. The Korean manufacturer produces top of the line air conditioner models with all the latest technology including inverter compressor that allows consistent cooling instead of peaks and troughs. Most of their models also carry a 10-year warranty on the compressor.

This is a sign that the company has confidence in its product and is willing to take the chance of repair and replacement costs for a decade. LG ACs work superbly even when the temperature outside is scorching and with its Himalaya Cool technology provides prompt initial cooling within a few minutes.

A true-blue Indian brand which has been around for many decades with happy customers everywhere. The Blue Star logo is very visible since they provide central cooling and indoor environment products to 1/3rd of the shopping malls and offices in the country.

Blue Star ACs offer the best in class cooling and can withstand competition from any foreign brand. With no less than 5 manufacturing facilities in India, they offer both window and Split air conditioners from 0.75 tons to 1.5 tons.

With the revolutionary iFeel technology with a second temperature sensor on the remote, it is designed to ensure the greatest comfort at home for you and your loved ones. Their air conditioners are also able to do a self-diagnosis when there is a problem and use error codes.

A brand whose expertise spans from making smartphones and laptops to air conditioners and refrigerators. The Korean giant is one of the world’s largest companies by any metric you want to use and at the forefront of new tech in all types of consumer durables.

The greatest strength of Samsung is its huge service network present in probably every small town in India. Samsung has on offer only split inverter ACs of 1 and 1.5 tons capacity obviously since they believe window air conditioners and traditional compressors are on their way out.

They offer the latest tech like 8-Pole inverter motor for durability and power and Smart Install using which the AC performs a self-test to find if it is correctly installed.

Hitachi, the Japanese conglomerate builds everything, from power plants to trains and air conditioners. It is enormously respected name due to its high quality and trustworthiness.

It was one of the first manufacturers to introduce copper coil condensers in 2014. Hitachi air conditioners are known for keeping a room cool during the hottest of summers without requiring any maintenance.

However, you pay for this dependability with a slightly higher price. You need to note that Hitachi service network does not extend as wide as the Indian and Korean brands. But if you are in a metro or a well known Tier II city, have no reservations about installing a Hitachi.

The founder of Carrier Airconditioning was Willis Harrier credited with being the inventor of air conditioning back in 1902. With such illustrious history, it is no wonder that they are the leaders in air conditioner sales across the world.

Carrier is the priciest of all the brands we discuss with a Carrier window AC costing as much as a split AC from many manufacturers. But in return, you get to display the Carrier name which is regarded as the Rolls Royce of indoor cooling. Pedigree is worth a premium and if you care for it you have to pay a little extra (or a lot).

There is no much scope for discussing how advanced their ACs are since in features they lead and others follow. Put aside “common” advanced features such as auto-restart or self-cleaning and look at novel ones such as Refrigerant Leak Detection. You will always find that they were pioneered by Carrier.

They are the tallest brand offering exceptional value for money in collaboration with Midea, a Chinese company with huge experience in home cooling.

Tatas have since long been well known and respected manufacturers of industrial goods. This goodwill extends to their air conditioning brand Voltas which is a joint venture between Tata and Volkart Brothers.

By the number of ACs sold they are the largest brand and that goes to show the faith that consumers repose in their products.

The Voltas air conditioners are economical to buy but not cheap and flimsy. With multistage filtration and all the newest features such as auto-restart and humidity control, Voltas is the clear leader in the industry.

Voltas also boasts of an extensive dealer network and a huge number of service centers spread throughout the country. No matter where you are, you can be sure that within a few miles you can find their technician to fix your problem.

To understand what to look for in an air conditioner you need to have some understanding of how the contraption works. The first thing you need to understand is what an air conditioner does. It does not make air cool! Surprised? What it does is take heat away. You cannot make something cold but can only draw heat away from it.

If that is as mystifying as what the salespeople say let me share an example. You have a bowl full of hot sambar or soup in front of you. You cannot consume it till it cools down. You turn on the fan. What the fan does is, circulate air and draws heat away from the dal. There is no coldness applied by the fan but taking heat away by making air move faster and faster.

Why is this important? Because in essence, an air conditioner is a heat exchanger. It makes a room cooler than usual by making some other place warmer than usual. Essentially taking heat from a room and transporting it outside the room. That is why if you stood behind a window air conditioner you would feel hot air rising from it. It is nothing but the heat from the room being transported to the air outside.

But how is heat transported out of a room, you ask? Have you ever had rubbing (isopropyl) alcohol applied on your upper arm by a nurse before she sticks you with an injection? Did it not feel slightly cool? Better yet put some aftershave (which also contains isopropyl alcohol) on your arm. You will find it feels a little cool.

This is because isopropyl alcohol evaporates easily at room temperature. But to evaporate it needs heat and it draws that from your skin. As heat escapes from your skin due to evaporation of the alcohol your skin feels cool.

Something that evaporates quickly is called volatile. If we could make something evaporate easily from inside a room we would be able to easily cool the room just like your arm felt cooler.

Chlorofluorocarbons are gases that evaporate at a very low temperature between 8°C and -30°C. This property is what led them to be used in air conditioners and refrigerators. It needs to be mentioned here that air conditioners and refrigerators are the same exact device. Whereas an air conditioner cools a 1600 cubic foot room to 20°C a refrigerator cools a 15 cubic foot cupboard to 3°C.

This is a highly simplified schematic of an air conditioner. An air conditioner is essentially a long tube filled with CFC gas.

The left half is the indoor unit in your room and the right half is the outside unit. In case of a window AC, the left half is inside the room and the right half outside the window.

There is a compressor that turns the CFC gas to a liquid by building up pressure. When pressure mounts up there is heat. The liquefied CFC gas is then forced into the condenser coils (red). As a result, heat is transferred from the gas to the metal in the coil in the same way as an aluminum pan becomes hot when boiling water is poured inside it.

The metal of the coil is in contact with the air outside which not being as hot as the liquefied CFC gas draws away heat from the coil.

The coil is several meters long and the longer the better because that offers more scope for air to come into contact with the heat emanated by the liquefied gas.

Thus the liquefied gas from the compressor travels through the condenser coils, loses heat and reaches the expansion valve. Through a tiny orifice, the liquefied gas is released into the evaporator. The sudden drop in pressure causes the liquid to instantly vaporize. But (and this is the trick of an air conditioner) no matter how low the boiling-point is, it needs some heat to evaporate. It draws this heat from the metal of the evaporator coil. The coil becomes much colder than the air inside the room. The air inside the room transfers its heat to the coil and becomes cooler.

In brief, sudden vaporization through the expansion valve causes the gas to become vapor. This needs heat and it draws the heat from the room. This heat trapped in the CFC gas is turned into liquid by the compressor and sent through condenser coil which cools it down. Thus heat from inside the room is brought outside which is why at the outset I mentioned an air conditioner is a heat exchanger.

This process happens several times every minute and at every iteration cools the room down slightly until after 15 minutes or so the room temperature is conveniently low.

It is important that a lot of air flows over both the condenser and evaporator coil. That is why both ends have efficient fans. The fan over the evaporator is called the blower.

A common-sense question to ask at this point is why does cooling stop at a preset temperature? Why does an AC not cool enough to reach 0°C. It would if it was allowed. The expansion valve stops it from doing so.

Notice the polished silver-colored cylinder next to the brass colored expansion valve. It is actually a sensor that is attached next to the evaporator coil. It senses how cold the evaporator coil is and switches off the flow of the gas and also working of the compressor.

If the compressor was allowed to run endlessly then there would be huge electricity expenditure. And the cooler the room gets the more the compressor has to work to cool it down by a degree. To prevent damage most ACs use some sort of protection mechanism to switch the compressor off from time to time. This is how a real AC looks if you could “blow” it up.

In reality, the compressor is located right next to the condenser coil and the evaporation valve is near to the evaporator coil. This arrangement allows for maximum efficiency in heat transfer.

Of course, one thing would have struck you by now. In winter if only we could turn an air conditioner inside out it could heat a room. A few air conditioners do that through what is known as a heat pump mechanism causing the evaporator coil to act as the condenser coil and the condenser coil as an evaporator. The Daikin FTYN series is advertised as a heat pump AC.

At this stage, I am more or less sure that you know much more about how an AC works than a salesperson ever will. Time has come for you to learn about the small print that carries important information about an air conditioner.

Buying an air conditioner is a tidy investment. Most of them are the second most expensive thing you will buy, after a car. In this section of the article, we attempt to demystify the art of buying an air conditioner.

At a typical shopping mall or mega electronics store, the salespeople are remarkably pushy and will throw around jargon with no meaning, such as “grooved copper coil”, “R-32 gas” which makes little sense to someone who is not an engineer.

1 Ton here implies the amount of heat required to melt a ton of ice in a day (which happens to be 288,000 British Thermal Units or BTU). A one-ton AC takes away 288,000/24 = 12,000 BTU of heat from your room in an hour and a two-ton AC takes away double that or 24,000 BTU in an hour and so on.

But much depends on ambient temperature if the surrounding air. In Indian conditions, it is considered that a one-ton AC can cool a small room (10 ft by 10 ft) with 2 people in it and a 1.5 ton AC can cool a larger room 12 ft by 13ft with 4 people in it satisfactorily from 35°C to 22° C. Most large office rooms (80 ft by 100 ft) use ten 2 ton AC units.

In colder climates, the tonnage needed is much less. In Germany where average summer temperature is about 25° C you would need half the tonnage to take the temperature down to a comfortable 19° C (of course in such a climate, heating that is more important for most of the year).

It is also important to note that apartments on the topmost floor are far hotter than those below. This is because they not only become hot due to warm air but also heat transfer by conduction from the roof. Any flat on the top floor will need a larger AC.

If you just wish for a summary, then for an average room a 1.5 ton AC is sufficient and a 2 ton AC is more than enough. For small rooms, guest bedrooms, doctor’s chamber, small shops a one-ton AC is enough.

The compressors in use till a decade back used a piston. There is an inlet valve through which gas entered the piston cylinder (much in the same way as a car cylinder) and the piston would push the gas into a more confined space thus compressing it into a liquid.

In case of a rotary compressor, it is force generated by a screw shape that creates the pressure (much like the water pump at your home).

The chief advantage of a piston-type or reciprocating compressor is that it is slightly more efficient (since it pushes) than a rotary compressor (which in effect squeezes). But a rotary compressor has a lesser number of moving parts, which means a fewer number of components which can fail, less maintenance, greater durability.

Probably many of the ACs you see around you have a non-inverter compressor (though they are on the whole on the way out). The sole problem is they are binary – either on or off. This means they cannot step down their performance once the room is cool.

What does it mean in real terms? The room has to be allowed to warm once it is cool and the compressor will again work and take away the heat. This is sort of a wave with highs and lows of temperature through the day. Ideally should not an AC maintain more or less the same temperature it is preset to?

This is what happens with an inverter compressor. Instead of switching off when a temperature is reached it just idles down a bit. An inverter compressor still continues to work but at a slower pace. An inverter compressor is designed to work at speeds from 1100 to 4500 rpm (revolutions per minute).  It never switches off unless the AC unit power is switched off.

The temperature is consistently maintained. This is much more comfortable and efficient. The compressor monitors the temperature level and steps up rpm if needed by 30% or steps it down. This is a vastly more efficient way of cooling.

A linear compressor has to bring down the temperature every time. This needs more energy and larger payout in the form of electricity bills. With the introduction of inverter compressors, there is a 30 to 50% drop in electricity bills.

Starting and stopping a device causes it to grow warm and cold. This heating and cooling have an effect on durability. Have you noticed how your ceiling fan rarely breaks down though it seldom gets any rest? That is because it is in a constant state. Change of state affects durability. Inverter compressors are better since they constantly run.

The mechanism of the inverter compressor needs less energy though they work longer. Pushing gas out by use of centrifugal force is a much more efficient way of pumping gas than using a piston.

Just like a car engine, a piston is noisier since it has more moving parts. An inverter compressor has a less number of moving parts and is quiet.

Do you notice in the graph above how the constant start/stop cycle makes the non-inverter AC consume more electricity on average as shown by the yellow line?

In this era of expensive energy who will not want to save more on a machine that is going to run several hours a day for many years. Even if at a minimum you save one-two units a day during summer that works out to several thousand rupees over 8-10 year life of an air conditioner. In actuality, you save far more.

We have all seen the snaking coil at the back of a window air conditioner. It is like the veins of the body through which blood flows and the refrigerant is the blood. The body is only as strong as the blood vessels and an air conditioner is only as good as the coils that make it. At the very beginning of this part of the guide, I had stated that an AC is nothing more than a very long metal tube filled with refrigerant gas.

There are two types of metals in use for air conditioning – copper and aluminum (usually some type of aluminum alloy).

Copper is far better than aluminum and alloy materials when it comes to condenser coils. A condenser coil needs to be able to pass heat quickly from the liquefied gas to the air outside.

Why then do manufacturers use aluminum in some models. The reason is cost. Copper is at this moment three times more expensive. In an era of cost-cutting, it is important to save every penny from a manufacturer’s point of view and the low cost of aluminum is attractive.

Not only is copper better at heat exchange but it is more resistant to corrosion. The corrosion of copper happens slowly and can be avoided by regular maintenance every year. Aluminum corrosion cannot be defended against so easily and there is bound to be fatigue and wear at the site of corrosion.

A leak in the copper coil can be repaired. However, it is far more difficult to weld or solder aluminum. That is why with any leak the entire coil subsystem has to be changed. If you can afford always choose an air conditioner with copper tubing. It will last longer and seldom fail if it is cleaned periodically.

It is the most mystifying of all the criteria. It is also the criteria where the most numbers of misstatements occur by those trying to sell you an AC. It is the Star Rating for energy efficiency that has been developed by BEE (Bureau of Energy Efficiency).

Note that the BEE ratings do not only apply to an AC, but refrigerators, bulbs and a variety of energy-intensive appliances. Since televisions consume no more than 50 watts they are as yet not sold by the BEE rating criteria.

The ratings have been developed to help a consumer understand how energy efficient a product is. This is important because you would be spending a vast sum of money to run a machine that is not very efficient.

If somehow I could bring to you a 20-year old air conditioner in a brand new box packed condition and sell it to you for only a thousand rupees do you think that would be cheaper than a modern AC which would cost you 30 times more?

Not really since that old design air conditioner consumes about 15 units of electricity every night and the new models spend no more than 2-3 units.

In about 18 months running the electricity bill would be large enough for you to have bought the new model AC (10 units a night means 5000 units over 18 months which is about the cost of a new model AC).

Moreover, think of the impact on the environment. Lesser the energy that is consumed by each family the better it is for all of us.

But how do the BEE Star ratings work? It is not as complicated as the Duckworth-Lewis method in cricket but will take some explaining.

It is the ratio between the cooling capacity of the AC measured against the electrical input in watts.

The question is how to know how many stars is 3.2 or 2.9 or some similar decimal. The BEE from time to time publishes it on its website. Remember it is also upgraded from time to time so what was a 5 Star AC in 2016 is a 3 Star AC today. Indian Seasonal Energy Efficiency Ratio (ISEER) is a measurement introduced by BEE in 2016.

The most important number to look at is the annual units consumed. It is always better to pay more for a higher star but only if the model is current. Do not pay a premium for a 5 Star AC from 2016. It is going to be a 3 Star machine now.

However, it has to be remembered that the BEE system that India follows is in development. And as yet we do not have a 10 Star system as in advanced countries. EER or Star Rating is an indication of how efficient a device is but cannot always declare it in absolute terms.

Do you buy a 3 Star AC for INR 32,000 or a 5 Star AC for INR 40,000? At the end of the day, you have to calculate the expected life and hours of running and take a decision about how much the extra electricity cost will be covered by the INR 8,000 savings.

The coolant gas is, of course, a very crucial part of an AC system. It is responsible for absorbing heat from the room and transferring it outside. It is repeatedly liquefied by the compressor and loses heat in the condenser coils and then released into the evaporator coil by the expansion valve.

This happens hundreds of times an hour and the nature of the gas as well as its ability to exchange heat is all-important. In the section “How Does An AC Work” the process have been discussed in detail. Let us take a look at the various types of refrigerant gases.

An air conditioner is a pricey thing. Also, they cannot be repaired very easily or even if repaired they can never go back to optimal factory settings and cool very efficiently. Hence the price is an important factor. Although the AmazonBasics model given above costs less, usual 1.5 ton split inverter AC prices start at about INR 34,000.

The price of some brands such as Carrier and Hitachi is more due to the excellent quality of product and goodwill.

But that is no guarantee that those expensive machines will not fail. Very often when an AC fails the entire subsystem has to be changed. Such as if the compressor is leaking, the compressor and a large part of the evaporator coils may need a change.

Also due to rapid changes in BEE standards, an AC no longer needs to last 20 years. A life of 10 years is what must be looked at considering that they have almost no resale value.

Brands such as Voltas and Samsung have a vast after-sales network. It is not something completely irrelevant when buying an AC. Make a Google search for the number of service centers in your city of every brand. Since no brand will have more than 2-3 you could even call a few to find how quickly they can send over a technician to check how fast they will react when you need them.

Brands such as Carrier have very few service centers. This is a definite negative at times unless you happen to live in a large metro.

A couple of brands offer a 10-year warranty on the compressor including gas replacement. This is definitely something worthwhile and needs to be looked at since a compressor is the heart of an AC. An assurance that you will not need to incur any cost on its replacement for a decade is really going to add to the pleasure of buying.

But at the same time make sure of what exactly the warranty covers. Very often companies will claim that the damage in the compressor has extended to the piping and they are unable to fix a new compressor since the piping needs to be replaced.

If you are buying an AC try and have a chat with company personnel (not the salesperson in an electronics mega mart) about what exactly the warranty will provide for.

Also, some companies have a more customer-friendly attitude and some try to wiggle their way out of a commitment. Before buying a model search for it on the internet and read the reviews (both positive and negative).

The nature of a company can often be understood through what a dozen or hundred reviews say. This is not to say that reviews tell the complete truth but they do give an impression. It is also crucial to know if you can install the AC using local workmen. Some companies do not honor the warranty if an AC is installed by unauthorized personnel. But in most cases, local workmen give quicker install and charge less.

Buying an AC has several factors accompanying it. I have tried to give you a bird’s eye view of every topic without going into extreme details. Hopefully, the information that you have gleaned from the above, beginning with how an AC works, what are its different parts, what is an inverter compressor, energy rating, and advantages of the copper coil will stand you in good stead when the buying decision arrives.

Last but not least, do not fall for bundled offers such as an OTG free with an AC. These are given at the dealer level for pushing off old stock. Take care to steer clear of too good to be true assurances.

This is a really difficult one to answer with the performance of LG, Samsung, Carrier, Daikin, Voltas within a hair’s breadth of each other. Due to BEE ratings, most of them consume about the same amount of electricity and have almost identical specifications.

However, in absolute terms, of course, a Carrier or a Daikin is better since they are specialized air conditioner manufacturers.

The Korean brands such as LG and Samsung have a vast service center network alongside Voltas. Carrier and Daikin have less presence in the smaller cities and towns and often deputize local repair shops to act on their behalf.

Yes, it is absolutely reliable. Large companies such as Amazon and Flipkart do not transport consumer durables but have a tie-up with local dealers who forward it using the online company’s logistical partner.

Copper is better at transferring heat but is thrice as expensive. Aluminum may corrode and is not as long-lasting. If you can afford it always go for copper piping.

Corrosion is the biggest enemy of air conditioners since no matter if it is a window or split, one part is exposed to the elements. Blue Fin is an anti-corrosive coating that prevents rusting to a certain degree and prolongs the life of an air conditioner. LG offers Ocean Black protection that is similar.

AC is usually made for wide fluctuation from 150 to 270 volts. But it is better to buy a good stabilizer since it is inexpensive and furnishes additional protection against power surges and brownouts.

Due to the presence of salinity and high humidity in coastal areas you should use copper coils and never aluminum coils. Moreover, make sure that there is good anticorrosive treatment like Blue Fin or Ocean Black.

It is a set of filters (between 3 and 7) that allows the AC unit to filter out dust, dirt, pollens, and bacteria from the air. This makes the air safe to breathe. The filters have to be cleaned at regular intervals and at times replaced when they become older.

During monsoon the humidity is high. At this time the AC turns on the fan constantly and removes the excess moisture. This is known as the dehumidifier function.

It is the technology present in LG air conditioners and uses two rotors inside the compressor instead of one to make it more effective.

LG air conditioners can emit ultrasound waves to keep mosquitoes away. This type of sound cannot be heard by humans but helps to drive away mosquitoes.

If I was going to buy the Blue Star BI-5CNHW18PAFU would be my first choice due to its second sensor in the remote. But at INR 51,000 it is slightly expensive and I would only buy it if I got a substantial bonus.

My choice if it was a cost versus benefit decision would be the Carrier ESKO NEO. At INR 48,000 it is not too expensive for a top of the line product. With an annual energy consumption of, 870 units the expenses come to about INR 6,100. Assuming it is going to be 30% more the expenses would be no more than INR 8,000.

In return Carrier gives me the best possible machine with R32 refrigerant and copper grooved tubing. It also has a 10-year warranty that I like very much. I am sure that a huge brand such as carrier would honor their commitment.

As far as price goes it is about 10% more expensive than Korean brands and less expensive than Blue Star. This makes it a really sweet deal.

Since the mega brand’s design for the US and European market, they are more adept at having highly skilled technicians should something fail. I have the advantage of living in a metro and having ready access to the Carrier service center and that has to some extent, of course, influenced my outlook.

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If I were in a Tier 2-3 city I would have leaned towards the LG, Samsung, Bluestar or Voltas because they would be able to provide support if there was an issue in the AC.

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