|A Split AC unit|
A Split AC unit has two parts. The indoor unit takes in air from the room, cools it , removes moisture and throws it back into the room. The outdoor unit throws out heat into the atmosphere.
Human body temperature is 37 deg. Celsius. A comfortable Room may have temperatures of 21-26 degrees Celcius with 20 to 50% relative humidity.
The heat removal load of an AC should be calculated precisely for every room because a lower capacity AC will not cool the room, and a higher capacity AC will make the room humid. Insist on your AC dealer submitting a cooling load calculation sheet explaining how much tonnage of AC is required for each room.
It should consider the following:
Insulation properties of walls, roof and floor Direction of walls (west-facing walls get hotter than south-facing walls) Number of people in the room Number of windows, type of glass Electric appliances such as lights, fans, TV, refrigerators or Computers
Typically any normal room with two occupants can be cooled by taking away 50 British thermal units (BTUs) of heat per hour, per square foot of the room area. So, for a 15 ft by 15 ft room, AC capacity is 11250 BTUs/hr (15 ft x 15 ft x 50 BTU/hr) If the room is heavily shaded, reduce the cooling required by 10%. If it has walls exposed to sunlight, increase the cooling required by 10%
Add 600 BTU/hr for every additional person in the room.
Add 1000 BTU/hr for every appliance.
British thermal units (BTU) is the amount of heat required to raise the temperature of one pound (0.45 kg) of water 1 degree Fahrenheit (0.56 degrees Celsius). 1 ''ton'' = 12,000 BTU
1 KW Kilowatt (1000 watts) = 3400 BTUs per hour
Make sure your AC runs on single phase. 3 phase connections are expensive to install and maintain. The efficiency of an AC is measured by the Energy efficiency rating (EER) is the ratio of cooling capacity to power consumption (BTU rating over wattage). The higher the EER, the better. Coefficient of Performance (COP) is another popular ratio for essentially the same thing. EER=COP x 3.412
Air Flow Or Moisture Removal ?
Air flow rate can impact speed of cooling, so the faster the air flow, the better. However, high air flow rates can mean lower moisture removal rates. Buy a model with higher moisture removal rate because high moisture levels can decrease comfort even if the air flow is good.
Which Compressor type?
Rotary vane compressors are more efficient and more reliable than reciprocating compressors because there are fewer moving parts. They are also newer in technology.
Most AC units have similar features. Ask for a detailed explanation of each feature and enjoy different explanations from different dealers.
Look for the following:
Wireless Remote Control, Auto diagnosis/ self-test, Auto Restart after powercut, anti-corrosion treatment for outdoor unit fins, temperature sensor on remote control, Fast cooling (power cool, jet cool), air direction control, dehumidifying function, automatic changeover to dehumidification, selectable fan and cooling steps, auto-wind mode, sleep timer, preset settings, on/off timer, filter cleaning warning alarm/LED, deodorizing filter, passive dust filter, washable front panel, on/off switch for indoor unit (in case your dog chews up the remote).
Can the bio-sani-fresh-logicool-plasma filter really protect your baby?
Many companies lay claims to their AC units having filters that remove bacteria, mold, fungus and smells from the neighbor's kitchen. At this rate of technological progress, AC filters will soon replace Viagra. Your home is only as hygienic as you make it. An AC can't make up for bad housekeeping.
Most indoor units have Noise levels below 50 db, which is ok. Make sure the outdoor units are rated below 58db. Also, make sure the outdoor unit is mounted on a sturdy support and there are no loose covers that will vibrate and increase the noise.
Locally assembled vs. fully imported
Many companies have assembly units in India where they assemble imported kits (to save on import duty). My experience is that a fully imported unit has a better chance of quality because these units are built on a larger scale for global consumption. Of course, a company that sells imported units can wind up shop at any time as they do not have any solid investments like factories to keep them committed. So you may find that there is no service or spares after a couple of years.
Which AC dealer?
An air conditioner depends on chemical processes to work, unlike a TV which is an electronic device. So, you can not expect a TV showroom guy to install and maintain an air conditioner (although they will tell you otherwise). Go to a technically sound expert for installation because in both compressor types, the refrigerant flows over the compressor motor to cool it. If the refrigerant is not charged sufficiently into the piping, the motor will burn out. If there is too much refrigerant, then the compressor gets flooded. In both cases, the compressor will have to be changed. If you are lucky, the rest of the AC unit will survive.
There is also a myth that the AC will lose its refrigerant gas after a few years. There is no reason why a system should lose refrigerant unless there is a leak and all leaks can be found during installation.
This is a ridiculous cost that every AC company charges you. Unlike a TV or refrigerator, an AC unit is not designed to be installed by the customer, so how can they charge extra for installation? Imagine Toyota selling you a car and charging you extra for tires ! So, negotiate and do not pay any installation charges, unless more than 2 meters of extra copper tubing has to be used for running refrigerant to the outdoor unit. The dealers get a cut anyway.
Finally, why do AC Prices vary so much?
The price of a one ton system can vary from Rs. 25,000 to Rs. 50,000°≠why?
1. Fully imported units have additional customs duty included.
2. Although expensive doesn't always mean good quality, sometimes a company charges a premium for good design, product build quality & performance over the competition. Something like the Mercedes. How do you know if this is the case? Insist on seeing a physical unit before you buy. Look for marks of bad product quality like slight differences in color shades between parts, visible or uneven gaps, "cheap" looking plastic covers or buttons, misaligned stickers or labels, bad packaging, uneven painting on metal, visible internal parts, etc.
3. Sometimes companies that make many consumer products (like Samsung, LG, etc.) can leverage their wide sales and distribution network for TVs to sell ACs. However, a company that sells only Air Conditioners (like Ogeneral or Daikin) must support a dealer network only for that one product and hence pass on extra cost to customers.
4. Company business models can differ, leading to price variations. A company may decide to sell only 50 units at a higher price while a competitor sells 500 units at a lower price.
Status Quo (November 2003)
Toshiba, Ogeneral and Daikin target the higher end quality conscious customers. Hitachi also is a higher-end player, while they have lower-end models under the Amtrex brand name. LG is fast getting there with their new range of Artcool and Mirror ACs, and they have a lower-end Plasma range competing with Samsung. Carrier is usually the cheapest.
Usually the time spent in buying a product is inversely proportional to its price.
Take time off and look at different options before you buy. Involve an AC expert early.