Buying an AC is more complicated than buying any other consumer goods. Apart from price, performance, and quality, you have to also give much importance to its running cost/energy cost. More often than not it becomes a balancing act between initial cost and recurring cost as in case of ACs, recurring costs are higher than the purchase cost. I am trying to explain some important technical aspects of an AC that should influence your buying decision, and also trying to group and rank some major AC brands commonly available in India. I bought mine from 86brands.com.
TECHNICAL ASPECTS:
TYPES OF AC: A room AC for home use can be a Window, Split, Tower, or Cassette(Ceiling) type, a portable AC is also available but that one is not efficient. Here I am not considering commercial solutions. Most commonly used room ACs are either Window type or Split type. A Window AC is a single unit fitted in your window or in a square hole on your wall. This one is cheaper to buy and maintain, and less prone to gas leak compared to a Split AC. However, Window ACs are more noisy and less energy efficient. A Split AC has one indoor unit and one outdoor unit. Though this one is costlier than a Window AC, it is less noisy, more energy efficient, and looks better also. In India most ACs are cooling type, but ACs with both cooling and heating(for winter) are also available.
INVERTER ACs: Inverter ACs are available in India for last couple of years. All Japanese brands and few other brands launched Inverter ACs in India. Standard ACs use a thermostat to automatically switch on/off the compressor to maintain required temperature level. As per the theory, such periodical switch on/off of compressor consumes more power. Inverter AC never switch off the compressor, instead, it uses electronics to run the compressor at variable speed to maintain required temperature. The AC compressor initially runs at high speed to reach required temperature, then slows down to maintain the temperature. Result is less noise and more consistent cooling. It has high EER, and probably saves 10%-15% energy compared to 5-Star ACs in case of continuous use for long time. Marketing departments make tall claims, like it runs at 50% power than a standard AC after 3 hours of operation, but standard ACs also automatically switch off itself. Some 5-Star rated ACs have higher EER than Inverter ACs. Most of the Inverter ACs use R410A gas. Companies also claim that these ACs have longer life, but on what basis is not sure, after all Inverter AC compressor never stops, it run continuously unlike standard ACs! Overall, it is more expensive but advanced technology, and the USP is more consistent cooling and energy efficiency.
THE REFRIGERANT/COOLANT: Commonly known as’gas’, this one is a crucial component of an AC. In India, most commonly used gas is R22, but since this gas is harmful for our Ozone layer, it is due to phase out from 2013 and will be available for servicing of old ACs only till 2020. However, non-ODP(Ozone Depletion Potential) substitutes of R22 like R417A and R407C will be available. The future of AC coolant is R410A gas. This one is widely used across the world, doesn’t make hole in the ozone, rather being costlier, it makes hole in your pocket:-). This gas is known to be more efficient coolant than R22. The AC pipes and compressor walls are need to be thicker to use this gas as it works at 170% more pressure than the R22 gas. Most Inverter ACs in India use R410A gas.
THE COMPRESSOR: A home AC compressor can be of three types, Reciprocating, Rotary, & Scroll, each being more advanced in that order. Most room ACs use Rotary compressors, Scroll is more efficient with bigger AC systems.
COILS: Copper coils are considered to be the best because of its longer life span. Check if your AC has copper coils.
TON OR TONNAGE AND BTU: An air conditioner unit’s cooling capacity is measured in BTU(British Thermal Unit). The higher the BTU of the unit, the higher is its cooling capacity. An 1 Ton AC means cooling capacity of 12000 BTU/hour(+/- 5% depending upon the model/brand of the AC). AC tonnage requirement is calculated on the basis of peak load, like afternoon of the hottest days. In India dealers push for more tonnage than actual requirement, that results into higher electricity bill. In fact, there is an opinion that a little undersized AC(in terms of tonnage) is power saving, as it will run for longer time at a stretch with lesser automatic switch on/off cycle, resulting in power saving. This doesn’t apply to Inverter ACs as these are capable of running at variable speed. You need slightly bigger ACs if the roof is exposed to Sun, or if the room has west facing windows, glass windows are worst unless those are hit resistant. When I was searching for the right AC, all dealers suggested 1.5 ton AC, but I went for a 1.2 ton model. During the afternoons of hottest days at Kolkata, this one chills my 160 sqft room on top floor with a roof totally exposed to sun. Now I think I could have bought a 1 ton also.
Also look at the dehumidifying capacity of your AC. Humidity increases temperature, so, ACs with a powerful dehumidifier performs better in very humid conditions.
ENERGY EFFICIENCY: This is a very crucial aspect that should influence your buying decision. An AC will consume the lion’s share of your power bill. With steeply rising energy costs, it is always advisable to go for the most energy saving ACs. This is how you can find one:
EER: EER or Energy Efficiency Ratio Indicates the ratio of the unit’s cooling power output(BTU/hr) to that of its Power consumption(Watts) & is a measure of Air Conditioner’s efficiency at maximum load. Higher EER means better energy efficiency and less power consumption for same level of cooling.
COP: COP or Coefficient of Performance is the ratio of Output Power to Input Power in Watts. A higher COP means a more efficient system.
STAR RATING:
BEE(Bureau of Energy Efficiency) has instituted a STAR rating system that enables us to identify which AC has the right EER or COP to facilitate lower running costs and hence help us save on electricity costs! The higher the STAR rating the more the efficiency. STAR ratings parameters are upgraded every year. For 2012, a 5-Star rating for a split AC means a EER(W/W) of minimum 3.30, last year it was minimum 3.10. Interestingly, for Window AC the 2012 EER (W/W) for a 5-Star is still minimum 3.10! Look for the color of the band in the rating sticker, if it is Green, then it is of 2012, Red means 2011 rating. Remember, a Red band(2011) 5-Star rating means Green band (2012) 4-Star rating. Star rating stickers are the easiest way to find a energy efficient system, be it an AC or any other electrical/electronics equipment.
There is a price gap of roughly 5000-6000 for a same brand 5-star & 3-star AC with similar features. Some argue that if the usage is low, then one may not recover the extra initial cost of a 5-star rated AC with savings in electricity bills. But, it is very difficult to limit AC usage during summer, plus the electricity cost is always rising. In my opinion it is better to go for the most energy saving AC. Further, advanced technology and better quality components go into 5-star rated machines to achieve such high energy efficiency. Overall, these are better systems in terms of quality also.