The compressor and its motor are manufactured to operate at constant speed or single speed only. In simple terms, it is either in the on (Full Power) or off (No Power) mode.
Therefore for Non Inverter, you will actually feel the air conditioner blowing cold air one moment and normal wind at another.
Due to this operating principle, the electrical consumption is higher and the compressor tends to spoil more easily because of the frequent start-stop. And there is no part load capabilities.
1) Orginally, Non Inverter air con uses only one big compressor linking to a few indoor units. Thus no matter how many rooms u use, you are always using the full capacity of the compressor. This is actually very inefficient. For example, the electrical comsumption will be the same when using 1 room and 3 rooms.
2) But as technology improved, most of the Non Inverter air conditioners in the market are using 2 compressors. For example, a System 3 will have 1 compressor of 8500 btu and the other at 12000 btu. The 8500 btu will be connected to 1 indoor unit while the 12000 btu will be connected to 2 indoor units. Therefore when operating 1 room, you will be using only 1 compressor.
** If you are using the 2 indoor units that are connected to the 12000 btu compressor, you will only get max 6000 btu each. **
3) May it be new or old, as long as it is a Non Inverter, you will get the 'cut in' and 'cut out' of the compressor. In other words, everytime the room reaches the pre-set temperature, the compressor will stop working. And when it senses an increase in temperature, it will start running again. Thus through out the night, you will experience the 'start and stop' of the compressor. In addition to that, the temperature will fluctuate as the indoor unit changes from 'COOL' to 'FAN' mode accordding to the 'start - stop' of the compressors.
4) Due to the frequently start-stop of the compressor, more eletricity will be comsumed as more power is needed to start the system all over again whenever it stopped. In addition, the compressor will also have a shorter life span.
5) Most Non Inverter Multi Split Systems have 'standard' combinations. For example, Sys 3 will be 9+9+9. When you required other combinations, you usually have to pay more as it may require a high capacity outdoor unit. And the largest indoor unit capacity for Multi Split System is 12k btu.
** For some brands, the largest can be 18k but usually it requires a higher capacity of compressor. The compressor capacity should never be smaller than the highest indoor unit capacity individualy **
So why not just have the Inverter and phase out the Non Inverter?
Price is the main reason. The difference can range from $600 to $800. Therefore for owners that do not have a habit of using air conditioner every night, it may be more worthwhile getting a Non Inverter air conditioner.
But do consider the following factors before making the final decision
a) the Electrical Tariffs might rise in the future.
b) your air conditioning usage might increase when your family gets more members.
c) you may be so used to sleeping in an air conditioned environment thus it becomes a habit even when it is raining outside.
d) the air conditioner might last longer than 5 years.
** These do not apply to those who have too much money and dun know where to spend **
What is an Inverter?
It is a power conversion circuit that is able to regulate the current, voltage and frequency of a device
Then what is an Inverter Air Conditioner?
This circuit board is able to vary the frequency of the motor which in turn control the revolution of the compressor. Therefore the compressor speed can be adjust to meet the cooling load neccessary. And with continous, precise and fast feedback process, changes in cooling load will be responed effectively thus minimising temperature fluctuation.
So how does an inverter saves electrical bills?
This is because of its part load capabilites. After an inverter air conditoner attains the set temperature, instead of 'switching off' like a non inverter, it uses the minimum power to ensure your room is maintain at the required temperature and adjust smoothly with response to any changes in the cooling load. Overall, you use less electricity.
But an Inverter air con costs more than a Non Inverter. Then why should I get an Inverter instead of a Non Inverter?
1) Because an Inverter is more energy efficient. Strictly speaking, you should calculate the 'breakeven period' or 'simple payback period'. If it falls within 5 years, then it will more economical to purchase an Inverter now.
2) When you lived in an old HDB with 8.5amp or 11amp current limit. But you want to install a System 4 for 3 bedrooms and 1 living. But a System 4 usually runs at a current of 11amp and above. Accordding to HDB regulations, you cannot install more than 1 outdoor unit or any outdoor unit having a running ampere of more than 8.5 or 11.
Therefore the only solution is to go for an inverter with variable current settings.
3) When you want a special combination like 15K+12K+9K. Only inverter allows you to choose the indoor unit combination freely.
4) When you cannot stand the outdoor unit noise level. Go get an inverter QUICK! Inverters are generally quieter in terms of outdoor unit than Non Inverters.
5) When you do not like anything that is using older technology. Tech Savy!!!!
Summary of Inverter Air Conditioners
1) Are generally of higher quality especially those using R410A refrigerant.
2) Has longer compressor life span.
3) Are very much quiet.
4) Will reduce your electrical consumption especially when using for long periods.