One- stage, Two- Stage & Variable-Speed ACs: Differences & Benefits

What are basic difference between the single stage means one stage and Two stage, variable speed ACs. Here in the article we discuss the benefits and differences of each unit.

one stage two stage variable speed systems

According to you the end story is that air conditioners cool your whole house. Right?

Well, no, the story is not yet. Because there are variety of options available now a day’s. It’s actually true when discussing the different air speed options.

So, that’s why you find our article on tempindoors, we are here to guide many house owners that there are variety of options available, so choose that option which suits your budget and your needs of comfort.

The average percentage of house owners does not know that what are the differences in the technology and between the one unit or system and another, Therefore, unless it is dissected by a specialist, it might all appear a bit alike to them. Many house owners are surprised when they know that the benefits of two stage and the variable speed air conditioners can be comparable to their present systems, even if their choices are not the best ones for them in the end.

We are now breaking down all the things just for you and doing face to face conversation like we were present in your house. Our goal, here we discuss all that factor through which our customer gets more benefits and choose the right and best option according to the comfort needs.

Also Read: Furnace Installation Process Step by Step (Complete Guide)

Differences between of One stage and Two stage air conditioners:

The major and main difference between these two is that the air conditioner which has two stages has a compressor which works in two different speeds but the air conditioner which has one stage having compressor which works at 100% or it might be completely off. The two stage compressor having one speed at 100% and another speed which is less than 100%. Although it varies by brand and type, the second stage typically has a capacity of 70%.

Probably, you are familiar with the one stage traditional models and equally you know that how it starts on or off based on the temperature. Imagine that you have the thermostat set at 72 degrees. Before turning on and cooling the house at 72, 71 and the AC may let the temperature to reach 73. The cycle then continues.

When the temperature close to that range then the System with the compressor of two stage works gently. Through this it uses minimum energy and preventing from frequently on or off cycle to 100%.  

Differences between the two stage and Variable Speed air conditioners:

Just like its name, the variable speed of air conditioner having more than 700 setting of compressor that represent various level of airflow intensities. Well, two stage compressor is far better and superior instead of one stage compressor in the terms of its efficiency and variety of options, but compares poorly to the compressor of variable-speed.

Probably, you heard about the SEER rating and how it actually measure’s efficiency. Variable speed of air conditioners is that when you are getting the SEER rating more than 20 which is the best central air conditioning system available.

Similarly, the two stage will be able to work at low speed and also it’s not necessary to have at 100%, but system of variable speed adjust its self, according to the power which is necessary to maintain the temperature in the house.

diagram how heating cooling work

Pros and Cons of One Stage Air conditioner:


The main benefits are its initial cost. Single stage of air conditioners is cheaper in price and its installation. If you are not having so much budget, then this is among your greatest options.

Air conditioner of Single stage provides cooling to the house frequently, but it’s necessary that it is properly sized and installed in an accurate way. Consequently, you don’t need to be concerned about that.


It is not having good efficiency which affects its cost of long term. You will get high energy bills when it is using 100% power and it consumes 100% power all the time. On the other hand, modern system run efficiently and quietly but frequently on or off of your air conditioner will be annoyance sometime.


The SEER rating of XR13 house air conditioners is more than 14.5 which basically give you the right and accurate cooling with high efficiency, which reduces the cost of cooling your house. XR13 basically gives you the comfortness and reliability to the house which you expect from the trane.

One stage

Pros or Cons of Two Stages of Air conditioners:

Two Stages air conditioner give you more and better efficiency instead of air conditioner of single Stage. Its efficiency and the initial cost will save your cost of energy instead of single stage.

Imagine it as the gas mileage. It will become more efficient when you are driving at lower speed instead of higher speed, frequently slamming on the pedal which can make damages on the car. The benefits according to the second, slower stage work better way in terms of efficiency and usage of systems.

Depending on the brand model, also based on the other variety of factors like size of the house, tag of the initial stage might be closer to the one stage or to the variable speed. SO, you have to talk with professional HVAC contractor that this is better option according to your budget or not.      


The air conditioner model like carrier 24ACB7 give you the perfect and accurate balance between the budget limit you have and your desired saving of energy for long term. It will give more than 17 SEER rating, there is a compressor of two stage in the unit which provide you cooling at the reduced cost.

Two stage

Pros or Cons of Variable Speed Air Conditioner:


Air conditioners with the variable speed are Cadillacs of the central air of cooling. They are working more efficiently and running quietly as well and They frequently use as little as 40% of the maximal power.

You are also saving energy cost and having greatest control on the temperature of the house. You will notice some spikes in the temperature, similar to those that occur during the on or off cycles of one stage and even the systems of two stages.

In other words, your house will be more pleasant all the time.


Higher initial cost and these systems are not cheaper and it cost you more money in the long run. The other major factor is repair cost. If suddenly one of the part of your system is damaged, then it cost you more money if you compared with the total cost of the system. But the advance and modern technology in the ac of variable speed can often increase the cost of replacement and the cost of labor.

If your system is in warranty, but labor cost is not included. So it can cost you more than repairing cost. Before choosing such type of system kindly talk with your HVAC partner.


Trane truComfort unit basically provide you ideal comfort by running at that speed through which it makes the house comfortable. It keeps the temperature maintained in the house means if the temperature outside changes it will allow your outdoor compressor fan to run at different speeds just to maintain the temperature of your house. XV20i TruComfort is a variable unit, it is one of the best and efficient air conditioner. The unit offers 750 levels of comfortness with more than 22 rating of SEER for the best possible climate and efficiency.

Variable speed

What the Types of Furnace Really Matter:

Anywhere any time you heard this words “Equipment matching”. If you really don’t know about this, it means there are variety of pieces in the system which work in a sequence to give you comfort it means such pieces need to be compatible with each other. These parts should be matched with furnace or AC’s.

Basically the blower motor inside your furnace moves the flow of air in whole system, also the air is also included which conditioned by air conditioner unit. So, if you want to run variable speed of air conditioner, you have to keep that blower motor which handles various stages.

It also means that it seems impossible sometime to upgrade your system from one stage to two stages or a system with two stage upgrade to variable speed without even upgrading the furnace or air handlers.

What are the things you want to upgrade the furnace just to use variable speed of air conditioner?  Well first know, How old the furnace is? It cost you so much when you thought to replace the furnace or air conditioner or both. But if the furnace is quite new, then find that option in which variable speed AC’s are not included.

Also Read: Popular furnace brands

Difference between Humidity and the Air Quality:

Humidity basically effects your house temperature more affectively. You know 70 Degrees temperature in the Arizona but it’s not same to the 70 Degrees temperature of Florida.

When the air conditioner runs, it basically removes the humidity from air and make the system work efficiently and effectively.

Two stage system remove more humidity from air as compared to single stage and if we go further then variable speed systems work more efficiently and remove more humidity instead of single stage.

Often it would be a great idea that connect the whole house dehumidifiers with the air conditioners just to increase more efficiency of the system. It true on any type of systems. You can also check the different type of systems just to check which system type give you what variety of controls. Based on the average level of humidity of the house and which type of system means air conditioner you finally selected, then set a detailed discussion about the dehumidifiers with your professional HVAC contractor.

Also Read: Should You Repair or Replace Your Heat Pump?

So use the system which run longer more than other systems, variable speed AC’s circulate air in the house and remove more particulates from air. It’s a good news for the whole house quality of air, but there is some implication occur like frequency of the filters cleaning. Also aware of all other considerations which your expert HVAC contractor thinks that it’s necessary to tell you about.

How much I can save from the Higher rating of SEER?

Depending on that which type of system you are using. Your system is fixed and running efficiently in result you are looking 65% of annual savings.

Well, I know it’s a great jump from 8 SEER to 22 rating of SEER but it is the best example to show that how the efficiency of your system increases when you move from old system to the modern and advance system.

It’s also important to keep in mind that not every jump is obvious. For instance, there is just a 3% projected cost variance between the 15 SEER and 16 SEER. When that happens, the conversation shifts from annual savings on expenses to comfort or budget.

Also Read: What is the Ideal Humidity Level for Your House and How You Control It?

SEER rating

Choose Best Air Conditioners:

Although there is no “best” choice in this situation, there are superior options for particular homes and residents.

We hope that after reading about the many varieties, you have an increased understanding of which could be right for you. Here are some other variables that could help house owners in their decision.

  • For what period do you intend to occupy the property? You won’t realize many of the overtime cost benefits from the variable-speed system if it is less than five years. But an efficient system frequently makes greater sense when you intend to raise a family at this home, for instance.
  • In this situation, size has its own impact. Although more effective than previous models, modern ones are also greater as a result. The biggest of the group are the variable-speed devices. verify that the space where you intend to house, the outdoor AC units is sufficient for the systems dimension. This also holds true for height. When you do not want a piece of furniture to protrude above a window sill.

There are variety of considerations for many peoples, but these are for some specific house owners. If you really want to know about furnace and air conditioners click learn more to get complete information HVAC systems.

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