Basic Things to Know Before Buying an Air Conditioner
An Air Conditioner (AC) is no longer a luxury in India; it has become an essential item for comfortable living. Before buying, it is crucial to understand the engineering basics: how an AC works, how much power it consumes, and how to calculate the right size for your specific room.
Air Purification and Dehumidifier Functions
Now with India's problem of air pollution, especially in winter months, you can convert your AC into an Air-Purifier. Since cooling is not needed in winter months, the AC can run in Fan mode with a special Air-Purifier filter, consuming only about 40 watts (similar to fan's electric use).
This new innovation air-purifier filter for ACs by 'AIRTH' (Filtrix) developed with technology from IIT Bombay and IISc Bangalore, works to make an AC to work as an Air-purifier as explained with full details on our * How to convert an AC into an Air-Purifier
Filter to convert an AC into an Air-Purifier:
🛒 Filter convert AC to Air-Purifier
What is inverter and non inverter ac
The difference in an inverter and non-inverter AC is mainly how the compressor of the two types of ACs work. The compressor in an AC is its heart and it uses almost 90% of the electricity used by an AC.
In a non-inverter AC, the compressor is either on or off. It runs at its set fixed speed when "On" and is completely "Off" or stopped at other times. For example, if the AC thermostat temperature is set at 23°C, the non-inverter AC will over-cool the room by -2°C to 21°C before the compressor shuts off. The room then warms up. When the room temperature reaches +2°C above set temperature of 23°C, that is when it reaches 25°C, the compressor restarts with a loud 'clunk' sound. This 4°C fluctuation leads to "hot and cold" spots and higher energy waste.
Inverter AC: An Inverter AC uses a variable-speed compressor that never truly stops. It slows down to a "crawl" once the room is cool, maintaining the temperature within a precise ±0.5°C range. Thus the Inverter ACs has a variable speed compressor, allowing it to be a 0.15 Ton to 2.25 Ton AC as needed. This also eliminates the noisy 'clunk' sound of stop and restart which disturbs your sleep and creates a far more comfortable, consistent environment. The inverter AC uses about 30 to 50% less electricity than a non-inverter AC, because it runs at a slower speed most of the time and it does not waste electricity by starting and stopping regularly. See our page on How inverter ac works
2. What is a "Ton" of Cooling?
The term "Ton" dates back to when ice was used for cooling.
- 1 Ton of AC = The cooling power of 1 ton of ice melting uniformly over 24 hours.
- In Technical Terms: This is standardized as 12,000 BTU/Hour (British Thermal Units). In metric units: 12,000 BTU/hr ≈ 3.517 kW/hr.
- In Simple Terms: A 12,000 BTU/hr unit can remove about 3.5 kilowatts of heat energy per hour, which is a common rating for a "one-ton" air conditioner that cools a medium-sized room.
3. Window AC vs. Split AC: Which is Better?
| Feature |
Window AC |
Split AC |
| Noise |
Noisy (Compressor is inside) |
Silent (Compressor is outside) |
| Installation |
Requires a large hole in the wall |
Requires a small 5-7cm drill hole |
| Fresh Air |
Can pull in fresh outside air |
Only recirculates indoor air |
| Aesthetics |
Blocks a window/bulky |
Sleek and modern |
4. AC Size (Tonnage) for Your Room
Buying an oversized AC is a mistake. It cools too fast without removing humidity, leaving the room feeling "clammy". Use this table based on Energy Star standards:
| Room Size (Sq. Ft) |
AC Capacity (Ton) |
| 100 - 150 |
0.75 Ton |
| 150 - 250 |
1.0 Ton |
| 250 - 450 |
1.5 Ton |
| 450 - 600 |
2.0 Ton |
Engineer's Tip: If your room is on the top floor with direct sunlight on the roof, increase the capacity by 0.5 Ton. Building a shade or insulating the roof with Thermocol can significantly reduce your power bill.
How an Air Conditioner Works
An AC doesn't "create" cold; it pumps heat from inside the room to the outside using a refrigerant like Freon.
- Evaporation (Inside): The refrigerant evaporates in the copper coils (Evaporator) inside your room, absorbing heat and cooling the air.
- Compression & Condensation (Outside): The compressor sucks that gas and compress it back into a liquid releasing the heat from inside to the outside through the Condenser coils in the outdoor unit.
Refrigeration Cycle explained: Evaporator, Compressor, Condenser, Expansion Valve
🌡️ The Secret of "Latent Heat": How Freon Actually Moves Heat
Most Indian students remember "Latent Heat" as a complex topic from school physics—the "hidden" energy required to change a substance's state without changing its temperature. In an air conditioner, this principle is the "engine" of the entire cooling process.
Instead of just blowing "cold air," an AC uses Latent Heat to physically transport heat from inside your home to the outside world using a refrigerant (Freon).
1. Inside Your Home: The Evaporator (Liquid to Gas)
- The Process: Low-pressure, cold liquid Freon flows through the indoor coils.
- The Engineering: As warm room air passes over these coils, the Freon absorbs the heat and reaches its boiling point.
- The Latent Heat Angle: To turn from a liquid into a vapor, the Freon must absorb a massive amount of energy—this is the Latent Heat of Vaporization. Even though the Freon is absorbing heat, its temperature stays the same during this phase change, allowing it to "soak up" an incredible amount of heat from your room.
2. Outside Your Home: The Condenser (Gas to Liquid)
-
The Process: The AC compressor in the out-door unit, compresses the gas Freon coming from the cooling unit inside the room. Compression of the Freon raises its temperature.
-
The Engineering: Outdoor air is blown over the hot Freon in the condensor coils, causing the Freon to release the heat it took from your room.
-
The Latent Heat Angle: As the Freon turns back into a liquid, it releases the Latent Heat of Condensation. This is why the air coming out of your outdoor unit is always hot—it is literally the heat from your bedroom being dumped outside.
-
See prices of latest 5 Star ACs available in India.
🛒 5 Star ACs on Amazon
👨🔧 Engineering Fact: This ability to move heat through phase changes is why an AC system is officially called a "Heat Pump." It uses the physics of latent heat to move energy against its natural flow (from a cool room to a hot outside).
Understanding Different Types of Air Conditioners
Split AC: The Most Popular Choice
The split AC has become the preferred choice for Indian households, and for good reason. Unlike window units, a split air conditioner consists of two separate units—an indoor unit that disperses cool air and an outdoor compressor unit. This design makes split ACs quieter, more aesthetically pleasing, and easier to install in modern homes where wall-mounted cooling is preferred. Split ACs are available in various capacities, from 1 ton for small rooms to 2 ton for larger spaces, making them versatile for different room sizes.
Window AC: The Traditional Option
Window AC units have been cooling Indian homes for decades. These compact, single-unit systems fit into a window frame or wall opening, making installation straightforward and cost-effective. While window ACs are generally more affordable than split systems, they tend to be noisier and may not suit modern architectural designs. However, they remain an excellent choice for those on a budget or living in rented accommodations where permanent installations aren't feasible.
Inverter AC: The Energy Efficient Revolution
Inverter AC technology has transformed the cooling industry by offering superior energy efficiency. Unlike conventional ACs that constantly switch on and off, an inverter compressor adjusts its speed based on the cooling requirement. This continuous operation at variable speeds results in significant electricity savings, reduced wear and tear, and more consistent temperature control. While the initial investment in an inverter AC is higher, the long-term savings on electricity bills make it a smart choice for Indian consumers facing rising power costs.
Portable AC and Central Air Systems
For flexibility, portable AC units offer cooling without permanent installation, though they're less common in India due to their higher running costs. Central air conditioning systems are typically found in commercial spaces, large bungalows, or premium apartments, providing comprehensive climate control through ductwork.
Top AC Brands Leading the Indian Market
Voltas: The Trusted Indian Name
Voltas has established itself as one of India's most trusted AC brands, combining affordability with reliability. Known for robust build quality and excellent after-sales service network across the country, Voltas offers everything from budget-friendly window units to premium inverter split ACs with advanced features.
Daikin: Premium Japanese Engineering
Daikin represents the pinnacle of air conditioning technology in India. Their inverter ACs are renowned for superior energy efficiency, quiet operation, and exceptional cooling performance even in extreme temperatures. While positioned at a premium price point, Daikin's durability and advanced features justify the investment for those seeking the best.
LG: Innovation Meets Affordability
LG has carved a significant market share by offering feature-rich ACs at competitive prices. Their smart AC lineup includes WiFi enabled models with AI capabilities, allowing remote control and intelligent temperature management through smartphone apps. LG's dual inverter compressor technology delivers fast cooling while maintaining energy efficiency.
Blue Star: The Commercial Cooling Expert
Blue Star brings commercial-grade cooling expertise to residential applications. Their air conditioners are built to withstand harsh Indian conditions, offering reliable performance and strong after-sales support. Blue Star excels in providing customized cooling solutions for diverse requirements.
Other Leading Brands
Hitachi, Samsung, Carrier, Panasonic, Lloyd, O General, Godrej, Whirlpool, and Haier each bring unique strengths to the Indian market. Samsung focuses on smart AC technology, Carrier offers premium cooling solutions, while brands like Lloyd and Haier provide value-for-money options without compromising essential features.
Essential Features to Look For
Energy Efficient Technology
With electricity costs rising, energy efficient ACs have become crucial. Look for high star ratings (preferably 5-star) from the Bureau of Energy Efficiency (BEE). Inverter compressor technology significantly reduces power consumption, with some models offering up to 50% energy savings compared to conventional units.
AI and Smart AC Capabilities
Modern AI AC systems learn your cooling preferences, adjust temperatures automatically, and optimize energy usage based on occupancy patterns. WiFi enabled smart ACs allow you to control your air conditioner remotely, schedule operations, and even integrate with voice assistants like Alexa or Google Assistant.
Auto Clean and Anti-Bacterial Features
India's humid climate makes air conditioners susceptible to mold and bacterial growth. Auto clean functions dry the internal components after use, preventing moisture accumulation. Anti-bacterial filters and coatings protect your family's health by eliminating harmful microorganisms and allergens from circulated air.
Fast Cooling and Air Distribution
Fast cooling technology is essential during peak summer when temperatures are unbearable. Look for ACs with powerful compressors and optimized airflow design. The 4-way swing feature ensures uniform cooling by directing air in multiple directions, eliminating hot spots in your room. Long air throw capabilities are particularly important for larger rooms, ensuring cool air reaches every corner.
Making the Right Choice
Selecting the perfect air conditioner involves balancing multiple factors: your budget, room size, climate conditions, electricity costs, and desired features. Inverter technology and energy efficient models offer better long-term value despite higher upfront costs. Trusted brands like Voltas, Daikin, LG, Blue Star, and Hitachi provide reliability and service support crucial in India's diverse market.
Consider advanced features like AI controls, WiFi connectivity, and air purification if you value convenience and health. Don't compromise on proper capacity selection and professional installation—these fundamentals determine your AC's performance and efficiency.
With this comprehensive guide, you're now equipped to make an informed decision that will keep you cool and comfortable through India's demanding summers while managing energy costs effectively. Remember, the right air conditioner is an investment in comfort, health, and quality of life.
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