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Convertible Technology: Why it makes sense in refrigerators, but not so much in Air Conditioners

By on May 3, 2022 with 4 Comments  

Imagine that you are in the market to buy a car. You are looking for one that has an automatic transmission (gearless). You want to have freedom from changing gears and ease of driving. But then you come across a model that is automatic transmission but also can change gears. This ability to change gears is being sold as a value proposition to you. Would you be interested in it? If you went to buy a car that is automatic transmission or the ability to change gears automatically, why would a feature that lets you change gears be important to you? There may be scenarios where you may want it, but you do not wish to change gears in most cases manually.

Something similar happens when you are in the market to buy an inverter AC, but you are sold a model that lets you change operating cooling capacity.

Let us understand how an Inverter AC works.

Inverter AC is a variable cooling capacity air conditioner. Like your automatic transmission car, it determines the running capacity of the AC depending on the needs of the room. A room never has a constant heat load. In peak summers, your heat load is more, whereas your heat load is less in off-peak summers. During the daytime, your heat load is more; at night your peak heat load is less. Inverter AC constantly analyzes your heat load and adjusts its cooling capacity depending on the heat load and the temperature setting on your AC, it determines its cooling capacity. Just like how an automatic transmission car determines the running gear depending on the speed of your car.

The automatic transmission car will automatically run at a lower gear if your speed is less. Similarly, when your heat load is less, or you keep your AC at higher temperature settings, the inverter AC will automatically run at a lower capacity. You need not set it manually. If your heat load is high or you have set the AC at a lower temperature, then the inverter AC will automatically run at a higher capacity, and you need not set it manually.

Temperature setting plays a big role.

What is important to understand over here is the role of the temperature setting. Temperature is a measure of heat in the room. A higher temperature means more heat in the room and a lower temperature means less heat in the room. If you set your AC temperature to 20 degrees, then it means that you want lesser heat in the room (or excessive cold). The AC will thus have to work more to remove the heat from the room and thus it means that it has to work harder. If you want to run your car at a speed of 120 kmph, then your car’s engine has to work more, work harder. If you run your car on 1st gear and expect that your car will reach the speed of 120 kmph, it will not happen.
Similarly, if you keep your AC at 18 degrees or 20 degrees and run your convertible AC at 20% capacity, it will not happen. But suppose your leave your inverter AC to decide its own running capacity. In that case, it will certainly figure out the right running capacity (if it can achieve that temperature). If you want a speed of 200 kmph, but your car’s engine cannot achieve it (even though you do see a speed of 200 kmph on your car’s speedometer), then your car will never achieve it. Similarly, even if you see a temperature of 18 degrees on your AC’s thermostat, if your AC is not big enough (does not have peak capacity) to cool the room to 18 degrees, your AC will never cool to 18 degrees.

If you know that you want to run your car only at a speed of 20 kmph, and you know that keeping your car at first gear will be good enough for that, then in that case a feature like having manual gear in an automatic car may help. However, the automatic transmission will determine that the car should run on the 1st gear and it will run it. Similarly, suppose your room needs lesser cooling capacity. It may be good to set it at a lower capacity, but then your AC will automatically determine that it needs lower running capacity.

Why does convertible technology make sense in refrigerators?

The key difference between convertible technology in refrigerators and that in ACs is that in refrigerators, convertible technology lets you change the freezer’s temperature and not the running capacity. Whereas in ACs, the convertible technology is about changing the running capacity. And this makes a huge difference.

For years refrigerators had a single heat exchanger for the fridge and freezer section, whichh did not allow independent temperature control of each section. If you increase the freezer’s temperature, the fridge will also become hot. Or, if you cooled the freezer, you would find that the items in your fridge would also become too cold. With inverter technology, it became possible to have separate heat exchangers for the fridge and freezer. This allowed for separate temperature control for the two sections. Imagine if you have a single AC indoor unit for 2 rooms, then you cannot independently control the temperature of each room. But if you have two separate AC indoor units, you can keep the two rooms at different temperatures. This feature gave flexibility in converting the freezer into a fridge. The inverter compressor could independently figure out the running capacity to ensure that each section’s temperature was managed. The key is that the sections were controlled by varying temperatures and not the running capacity of the compressor.

In the case of Air conditioners, there is only 1 section (or one space or 1 room) to cool. And there is only 1 indoor unit (or heat exchanger). And it already has temperature control built-in. There is no real benefit of having a convertible feature in this scenario.

Is there any Scenario where convertible AC makes sense?

None that I could think of. Even if you are on rent and do not know the cooling requirement of your future rooms, or you have a transferrable job and do not know the requirements of your future houses, you do not need a convertible feature. The best thing you can do in such a case is to go for a big enough inverter AC that can handle the most cooling capacities you may need. So, a 1.5-ton inverter AC will work perfectly fine for a room that needs only a 1-ton cooling capacity.

Does Convertible technology save electricity?

Not much. If your room needs your AC to run at 40% capacity, inverter technology will ensure that your AC runs at 40% capacity. The energy efficiency of the AC when it runs at 40% capacity will exactly be the same as the energy efficiency when you manually set it to run at 40% capacity. If you do not set the running capacity, the only difference would be that it will start at 100% capacity and then come down to 40% capacity (cooling your room faster. In contrast, if you start the AC at 40% capacity (capped), it will not go beyond 40% cooling capacity. It will take more time to cool when you cap it, but it may save a small bit of electricity that it may have spent by running at 100% initially and then coming down to 40%.

I must state that an inverter AC runs at better efficiency when it runs at lower capacities than at higher capacities. To read more about it, check this link on this website: Why and How Does Inverter Technology Save Electricity?

Conclusion

The whole idea of this post is to help you decide if you should focus on getting convertible ACs, and for that, I would say, do not pay extra to get this feature. It is not a deal-breaker. Look for better energy efficiency, and do not worry if an AC is convertible or not.

P.S: Just like automatic transmission cars have AMT (Automatic Manual Transmission) and CVT (Continuous Variable Trasmission) options, similarly inverter ACs have stepped and continuous variable-capacity compressor options. A continuous variable-capacity compressor will have a smoother operation and finer temperature control.

About the Author:
Abhishek Jain is an Alumnus of IIT Bombay with almost 10 years of experience in corporate before starting Bijli Bachao in 2012. His passion for solving problems moved him towards Energy Sector and he is keen to learn about customer behavior towards Energy and find ways to influence the same towards Sustainability. .

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