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Dual inverters are significant in A/C

The Advantage Of Dual Inverters In HVAC Systems

You have probably seen ads about dual inverter air conditioners. It is being marketed by appliance manufacturers who are big names in the industry. They make claims that you will get much better performance and efficiency, but is that true? If you look at the brands who are marketing dual inverter appliances, they are industry recognized names like Whirlpool, LG and Hitachi.

HVAC Basics

The typical home requires 1 ton of air conditioning for every 400 to 1,000 square feet to cool or heat. For removing heat, the ton refers to the amount of heat that an A/C can remove in an hour. The amount of heat is measured in units called BTU (British Thermal Unit). For example, a 1 ton A/C can remove 12,000 BTU per hour. The more tonnage rating an A/C unit has, the more air it can cool. The specifications depend on the type of A/C and the manufacturer.

When it comes to HVAC systems, compressors driven by motors are an important element. BLDC (Brushless Direct Current) electromotors provide the power for compressors, which are mechanical devices that increase the pressure of vaporized refrigerants and pass it through condenser coils. The condensed refrigerant releases heat in the process, that has been removed from a space in order to provide cooling. In an air conditioner (A/C), the heat is released to the outside and the refrigerant returns to a liquid state and is recirculated back to vapor through the evaporating coils. The function can be reversed in some A/C, this time to provide heat instead of cooling during winter.

The problem with higher tonnage is that in order to remove all the heat to cool the air, plenty of energy is required. We have to understand that not all rooms are the same. Some are large (e.g. convention halls) while others are small (e.g. bedroom). The heat load varies with different conditions and even if the rooms are the same size. There are certain factors that determine the heat load besides room size like ceiling height and how heat gets inside the room (e.g. insulation). For example, a well insulated room with more shade and less exposure to sunlight and outside heat would be cooler thus requiring less tonnage.

This is what led to the development of dual inverter systems, which use variable tonnage. Thus it is more efficient since it does not require using the full capacity tonnage when it is not needed. For example, when only 3 tons is required, an A/C unit does not need to operate at its full rating of 5 tons. This is just an example to show the logic behind variable versus fixed.

Dual Inverter

A typical A/C inverter uses a variable speed single-cylinder compressor with a single compression chamber. The inverter operates the compressor for modulating the cooling capacity of an HVAC system. The dual inverter uses a twin rotary compressor. It has 2 compression chambers that produces a phase difference of 180° compression timing. The rotary compressors work between 720 rpm and 9,000 rpm (Revolutions Per Minute).

The Benefits

With dual inverter compressors, the benefits are significant when it comes to:

  • Energy Efficiency
  • Lower vibration
  • Faster Cooling

Energy efficiency brings cost savings to homes. Some brands claim 53% savings since dual inverters consume less energy. There is also less energy lost, which means less waste in cooling and heating. This also requires lower frequency of rotation and therefore less demand for power.

The lower vibration means less noise during operation. In single inverter systems, the rotor operates at high speed rotation which creates more noise due to more vibrations. At full capacity it generates plenty of noise. In a dual inverter system the rotors turn at a 180° phase, which is more stable when operating at full capacity. This results in fewer vibrations and thus less noise.

Faster cooling time is another benefit due to precision in temperature control. The rotor speed is varied according to the external demand on the A/C. It also doesn’t need to run at maximum speed to achieve this. Dual inverter systems use twin rotators that provide variable tonnage when removing heat from the air. This allows reaching the desired room temperature faster than conventional A/C.


Efficiency has become important in the last few decades. This led to more energy star compliant appliances that consume less power and demand less energy to operate. This was due to concerns of higher carbon emissions and the high costs of burning fossil fuels. The introduction of dual inverters in A/C made variable tonnage possible. With variable tonnage, the A/C can adjust to the rotor speed and tonnage based on the temperature of the room or space. When it comes to performance it does not mean dual inverters are always better than its conventional A/C counterpart. They are just more efficient. As the room cools, the compressor reduces its power consumption and electrical costs. For homeowners, this translates to greater savings.



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Vincent Tabora

Vincent Tabora

Editor HD-PRO, DevOps Trusterras (Cybersecurity, Blockchain, Software Development, Engineering, Photography, Technology)