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Why The Inverter Air conditioning Range Of Operation Is Important



Inverter air conditioning has revolutionised energy saving for the air conditioning industry since its introduction around the time R407c was introduced as a interim refrigerant. Air conditioning compressor technology before inverter technology used fixed speed compressors which came on or off according to the thermostat setting where a inverter air conditioning compressor operates at a variable speed according to the temperature setting slowing and speeding the variable speed compressor to keep the temperature at a constant and linear temperature.

An inverter air conditioning unit is perfect for linear temperature control but there are limitations, if the air conditioning unit is undersized for the area the inverter compressor will then operate at a high speed level which in affect works comparably with a fixed speed compressor working at 100% capacity thus using more power. The flip side to this is if the inverter air conditioning compressor unit is oversized for the area the unit will not be able to operate within its designated range. Inverter air conditioning units have a working range for their capacity which usually starts at a minimum of 1.0kW on small models. Below is a common operating range of capacity for inverter air conditioning listed by the main manufactures Mitsubishi and Daikin air conditioning:


Typical Inverter Air Conditioning Operating Ranges:

2.5kW / 9000Btu Inverter air Conditioning units (0.9kW to 2.5kW)

3.5kW / 12000Btu Inverter air Conditioning units (0.9kW to 3.7kW)

5.0kW / 17000Btu Inverter air Conditioning units (1.3kW to 5.4kW)

7.0kW / 24000Btu Inverter air Conditioning units (1.9kW to 8.23kW)


Why It Is So Important To Size The Area Up Correctly:

The above figures are relevant when selecting your air conditioning heat pump inverter unit for the area to be cooled / heated as they give the user a idea of the minimum heat load. This is usually overlooked as most users go for a slightly larger capacity for their area to be on the safe side. The downside to this is the compressor short cycles and never runs to full capacity. A good example of this is a 3.5kW air conditioning unit that has been installed in a area that requires ideally a 2.6kW air conditioning system. The 3.5kw unit has a minimum output of for example 0.9kw which mean that while operating at its minimum operation limit it will not take long to cool or heat the space and the compressor needs to switch off before it over cools or over heats the area. This will affectively mean the air conditioning compressor will switch on and off when it is designed to run continuously to keep the temperature setting and it is operating beyond its design capabilities and limiting its life expectancy. The energy savings that the inverter air conditioning compressor was designed for is ineffective when installed in a large area.


Key Considerations When Sizing Up Inverter Air Conditioning:

  • Do not oversize the air conditioning unit as it will end up switching off and on like a old fixed speed compressor

  • Do not undersize a inverter air conditioning unit as it will run at full speed like a fixed speed compressor

  • Look at the operating range when sizing up your area

  • Try to match the capacity to the room size to the nearest 500 Watts




Full range of inverter systems can be found by following this link to our sales website

Mitsubishi Heavy Industrial SRK20ZJX-S (2.8 kW / 9000 Btu) HYPER-INVERTER Air Conditioning

Mitsubishi Heavy Industrial SRK25ZJX-S (3.0 kW / 10000 Btu) HYPER-INVERTER Air Conditioning

Mitsubishi Heavy Industrial SRK35ZJX-S (3.9 kW / 13000 Btu) HYPER-INVERTER Air Conditioning

Mitsubishi Electric Super High COP Inverter Heat-pump Air Conditioning unit

Fujitsu ASYA18-LE Wall Mounted Inverter Air conditioning (5.2Kw / 17000Btu) Inverter


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Tel: +44(0)0845 567 7080





Orion Air Conditioning & Refrigeration Ltd, 10 Grisedale Court, Woburn Road Industrial Estate, Kempston, Bedfordshire, MK42 7EE, UK

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Last updated - 22/07/2018