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Inverter air conditioner

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Air conditioner Inverter vs. Air conditioner not Inverter or stable speed

Until a few years ago every single air conditioner unit was those of stable speed, what does it mean? It means that when we switched on our unit with a remote or wired remote our unit began to run and it worked at its full power, at its 100% of capacity, when it reached to the adjustable temperature or when we stopped it manually, the unit “stopped” completely and it didn’t keep throwing cold or heat (heat pump). Well, and now what?

The air conditioner stable speed units have or used to have (nowadays practically there aren’t for sale units which are not the inverter ones) some good things that we are about to set down now, although in general the new models with inverter technology beat those old ones, nevertheless we are going to remember the good things the air conditioner stable speed units had, for those old good times!


Advantages of air conditioner stable speed units


Cold feeling:

Neither once nor twice, nor thrice but more times I have been told:

“I’d like more the not inverter machines, at the very moment it was switched on and every time the machine was running, a much colder air was felt, it was felt from the beginning, the inverter machines it seems that they don’t cool down!”

Well, that’s true and not at the same time, the air conditioner stable speed units only have 2 speeds (0% and 100%) and when you start them they pass from being completely stopped to be at their full capacity because they give their maximum capacity right after switching on them. That’s the reason we could feel in the intensity of current of our house or office creating in many occasions a lowering in the light intensity of our room, dining hall, etc. It was noticed like the bulb didn’t give off much light just when you switched on the air conditioner (voltage descent) due to the big energy consumption the unit needs to pass from 0% to 100%, later the situation was settled and there weren’t more intensity descents (until the next starting), that’s why after starting the unit directly to 100% of its nominal capacity and maintain itself through all time the unit was running, we noticed that feeling of an intense cold so many people miss, the inverter air conditioner units don’t work this way, because these begin running slowly and then they accelerate to its full capacity reaching a 140% of its nominal capacity, but…

What does this thing about the 140% mean? We are going to explain that later


The reparations are easier and cheaper:

That’s absolutely true, the older air conditioner unit and in general, not the inverter ones, used to be more economic when we have to repair them, but why?, this answer is very simple, the older machines have less electronic boards (some of them don’t have), the starting condenser is isolated from the boards (in the inverter ones is integrated) and you can buy private label condensers because they don’t have to be special for every unit, some of them have relays which replace in many cases the electronic boards, the relays can also be from private label,  the fan motors used to be single-phase motors and they don’t have any electronic board integrated (yes, even fan motors of inverter units, if they are direct current they have a board inside the motor), the compressors are stable and no inverter and therefore you can always adapt one of another brand if there isn’t any spare part or this is very expensive and thanks to its easy way of reparations because they don’t have much electronics, every expert can solve a problem.

And now what?

I consider there aren’t more advantages. It’s true they are a few, because of that and because the evolution is wise, they were born and got multiplied the inverter air conditioners.


Advantages of inverter air conditioner units


Speed in cooling and warming

We said before that stable units gave us a feeling of a “colder” air, that’s not true, but not always.

It’s true that inverter units start slowly, it’s like a long-distance race, starting this way there’s neither a change in the intensity of current nor we feel a change in the intensity of bulbs, but they began to increase its capacity until they reach a 140% capacity in some cases.

What do you mean?

In comparison to steady speed air conditioner units which either go or don’t go, the inverter air conditioner units have a wide range of operations, that’s the reason why catalogues used to show three different capacities: the nominal capacity, which is the “real” capacity or “basic” of that air conditioner and it’s the one we have to use to do the numbers more accurately (there are so many people who are wrong when taking as a reference the maximum capacity), the minimum capacity and the maximum capacity.

Calculation to choose the inverter air conditioner

The nominal capacity, as we said before, it’s the real capacity, the one we must use in order to calculate everything.

The minimum capacity is the lowest strength or capacity this unit can give

The maximum capacity is the highest strength or capacity our inverter air conditioner unit can give. As we said, this capacity can’t be the one taken as a reference because sometimes it reaches a 140% of the nominal capacity, which can’t stay at that level for a long period of time. In general, it will reach its maximum capacity fifteen or twenty minutes every working hour, but it will suppose to the compressor to force itself and that will be inadequate. In any case, it will be the own machine and its electronics which will decide that, we don’t have to worry about anything, “the machine knows what it’s doing”.

The A+++ MSZ-FH25VE Mitsubishi inverter air conditioner unit provides us a very high EER and COP in cold and heat mode.


Now I give you a practical case for a better understanding, taking as a reference an actual machine from Mitsubishi Electric and the best of them (MSZ-FH25VE model) we see in its technical specifications three different capacities in cold:

2,5 (1,4-3,5) kW

2,5 kW will be the machine’s nominal capacity, with this we will calculate if this air conditioner unit is adequate or not for the place we want to air-condition.

1,4 kW will be the minimum capacity the inverter air conditioner unit can give us, being the 56% of its nominal capacity.

3,5 kW will be the maximum capacity. Our unit, even being a 2,5 kW unit is able to give a 140% of its capacity or 3,5 kW, which is the same.

As we can see in the inverter units, in this case, the MSZ-FH25VE Mitsubishi has working range between a 56% until reaching a 140%. The machine will be the responsible of giving the strength needed for having the best comfort in the shortest period of time, thanks to its characteristic of surpassing its nominal capacity which achieves to air-condition any room in less time than a stable speed air conditioner unit or not inverter.


Less consumption

As we have explained in the last paragraph, the inverter air conditioner units may vary its capacity according to their needs, this makes the consumption to get adapted and lowers the electrical consumption significantly.

If this wasn’t enough, thanks to its electronics, it is capable to run always at its finest conditions, adapting itself to the climate, though it’s very cold or very hot.

The stable speed units were very old in comparison to that, for they don’t have such electronics and they couldn’t modify its way of running and they worked in the same conditions though the weather was a 24ºC normal day or an extreme hot day with 38ºC, some stable speed units had pressure relief valves and condensing controls or different fan speed in the condenser, but this is nothing in comparison with all the things an inverter unit can do, regulating the gas flow with the electronic expansion valve, reducing or increasing the compressor speed, such as the condenser fan motor does.


More comfort

The inverter air conditioner units get more comfort and faster than the stable speed ones.

As we have explained, the inverter units reach to an assigned temperature faster than the stable speed units, apart from that, being capable of regulate their refrigerating capacity maintain the room in a much more precise way than the stable speed ones because they go reducing their capacity slowly while reaching the desired temperature, maintaining that temperature “never stopping”. And that is put in inverted commas because I have heard that a lot:

“The inverter units never stop, my machine never stops”.

A smaller fluctuation in the air temperature improves significantly the comfort and well-being feeling.


That is not true, the inverter air conditioner units stop, of course they do, but they do it few times, why?

In comparison to a stable capacity unit which switches itself on when the temperature goes a degree over our assigned temperature (cold mode) and it stops when it exceeds -1ºC, the inverter units work in a different way, these go reducing its capacity slowly when they reach their objective, and that’s the reason why seldom they exceed or reduce the temperature more than what it’s needed because it will keep itself a few degrees over or below our assigned temperature. It doesn’t mean it doesn’t stop, it does, but in general reducing its capacity and therefore its consumption is enough to keep the desired temperature.



Much more capacity

The inverter air conditioners are way much more efficient than those which aren’t inverter and they achieve an energy coefficient wider.

This is the biggest war horse ever in the invert air conditioner units: consumption, capacity. It is obvious that among their improvements towards the stable speed units, this is the most important. Thanks to its electronics and the obvious progressions over these years, an actual inverter unit can reach a 5,15 energy coefficient, that in comparison with a 2,76 of a non-inverter unit but same model, it is something to be aware of, it is almost the double of capacity and for that it means the half of consumption when doing the same work and air-conditioning the same room. Just for this reason choosing between an inverter and non-inverter one should be an easy choice to anybody.


Wider working range

Another inverter air conditioner characteristic which makes it better than a not inverter one is its working range, for example in heat mode. When the outside temperature reaches between 5 and 0ºC, a not inverter unit starts to fall its capacity heavily, even becoming ineffective and useless if the temperature descends even more, This is due to working in heat mode, the condenser will be cooling and it reaches to a point when it produces frost and it finally freezes itself, making impossible the heat or cold exchange with the outside. This is a solution with the called “defrost”, which almost every inverter unit has. With this defrost mode, what the unit does during a few minutes is to send the heat that should be going to the outside in order to warm our house, it sends it to the external unit to defrost it, loosing with this process the heat that should be impelling in the internal unit.

After that, the unit will work normally until the next defrost, which will be more usual and shortened in time if there is more cold and humidity in the outside.

The inverter units don’t have such problems, or, if they have it is much less pronounced due to its electronics regulate the gas flow for this not to happen thanks to measurements, being able to work to -15ºC and loosing much less capacity than not inverter air conditioner units.

It also exists special inverter units which works to -25ºC, giving a full capacity when they reach -15ºC, like Mitsubishi Electric Zubadan units.



Given the pros of one and another kind of technology, I believe there are no more doubts about the benefits or not of buying an inverter or a stable speed unit; an inverter unit gives more comfort, capacity, saving and it has more working possibilities given the weather. On the contrary, the only benefit I see to a not inverter unit will be it costs less if it need to be repaired, because they are easier and cheaper to fix, but this is only a benefit that you will only “enjoy” if your air conditioner breaks down =)



If you’re thinking about acquiring an inverter air conditioner unit, we recommend you to take a look at these links before picking one or another. These are the comparatives we did.

Comparative high range air conditioner

Comparative of a cheap air conditioner


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