Wednesday, May 30, 2007

All About Air Conditioners

When Should I buy an AC?

In winter you get them for a lesser rate. However, effective warrantee gets reduced. Also new upgraded models generally come out in summer. So as per me the best time is April- May.

What are the type of AC? Which one should I buy?

For use in normal household there are two choices 1) Window AC 2) split AC. Cooling capacity is not dependent of the type of AC you buy. Split AC s are more stylish and often less noisy. But window ACs are cheaper. My suggestion would be go with window AC. If you don't have window at correct places, consider split AC.

I get confused by the technical terms. What are the key parameters

Cooling capacity is expressed in terms of BTUs and Tons. The explanations are as follows- A BTU (British Thermal Unit) is a common unit used for measuring heat output, equal to the amount of energy required to raise one pound of water one degree Fahrenheit. One ton equals 12,000 BTUs/hour-a term derived from the amount of energy required to melt 1 ton of ice in a day.

EER or Energy Efficiency Ratio is a measure of how efficient a particular air conditioning unit is. The higher the number, the more efficient the unit and the less it will cost each year to run. Typical EER is between 8-11

What cooling capacity would be okay for me?

Don’t go by what sales man or company websites say. I have checked several articles and have developed a simple worksheet. (Check the calculation page). Normally for a Room size of 150 sqF, 1 Tn should be sufficient. It also depends on the insulation, other appliances, no of people staying in the room etc.

What if I buy a oversized or undersized AC?

An undersized unit won't cool adequately in extremely hot weather.
An oversized air conditioner would also adversely affect your comfort. The compressor unit would switch on and off too often (every 3 min), without running long enough to dehumidify the room properly or cool the space uniformly. And it will consume more energy than necessary. Further Higher BTU ACs consume more electricity. I have read that an undersize AC is better than an oversized one. Unfortunately in India most of us have oversized AC and we get matching electricity bills.

What are the aspects, I should look for in an AC?

First calculate the capacity you need (0.6 Ton- 1.5 Ton or more)
High EER, low power consumption
Don’t go for a local made. Go for a branded one. Make sure that the AC has rotary compressor.
The AC should have a wide range 18 deg- 30 deg
It should be digitally controlled (you can set them more accurately for lesser billing)
Be sure that your air conditioner comes with at least a one-year warranty that covers labor and parts on the entire unit. Warranty on compressor is normally 5 years.
Variable Fan speed setting
Filter is removable from the front side. If you don't clean the filter, cooling efficiency would come down.
Sleep mode or energy saver mode- These would help to cut energy usage by 25%

What are the aspects I should keep in mind while installation?

AC should be preferably placed in the middle of the room.
Direct Sunlight on ACs should be avoided. (If you have a choice- don’t install on the west side)
Seal the room properly for more efficient cooling.

Which brands are the best?

It is said that Hitachi and carrier are the best. But they are expensive too. I have done a comparison for 1 Ton Ac and the same can be seen in the "comparison" worksheet.

Information compiled by Avijit Das, Plot- 67, Sec-32, Gurgaon- 122001, Ph- 0124-4125114, e mail