Single Stage vs Two Stage Air Conditioner | One Should Be Avoided

Before you decide whether to purchase a new single stage or a two-stage air conditioner for your home, you have to know some key information about each product and how it can benefit you and your family. Most sources will give you almost the same answer which of the two is the best, but you might be surprised by what they don't tell you. 

DP single vs two stage air conditioner

The most basic difference between the single stage vs two stage air conditioner is the type and speed of the compressor. The compressor is the heart of an air conditioner and is used to circulate the refrigerant in the system under pressure.

While the compressor does all the heavy work, the properties of the refrigerant is what produces the cooling effect in the air. Single-stage works at one level only: 100% capacity or High, while the two-stage AC operates on two levels: Low or 60% to 80% (depending on manufacturer) of the maximum, and High or 100%.

One Stage Air ConditionerTwo Stage Air Conditioner
Compressor has one level of operation: HIGHCompressor motor has two levels of operation: LOW & HIGH
Cools your home at 100% capacityRuns at a lower speed and takes longer to cool
Price: $2500-$3500Price $4000-$5000
Repair cost: LowRepair Cost: Moderate to High
Basic and easy-to-find parts for repairs and could be performed by most HVAC techniciansComplex technology with harder-to-find components. Few technicians are trained to fix and maintain
Less prone to breakdown and mechanical problems due to simplicityMechanical problems more likely due to complexity
15-25 year lifespan7-12 year lifespan

It’s important to understand how single stage and two stage air conditioners differ before deciding which type is appropriate for your circumstances. Many people may be buying an air conditioner for the first time - but once you’ve had a bit of experience purchasing units you might not want to be enticed by promotional offers that aren't really going to get your home more comfortable.

Imagine that you've just moved into a new home. You're probably not thinking about how long your appliances will presumably last in your house - but appliances like an air conditioner tend to stay with you for years. You want to make the right choice.

If you’ve had an old air conditioner and it recently broke down, you may be thinking about purchasing another one of the same type that you already have. You might do this because it lasted a long time, or because your current AC was adequate and you were happy with its performance.

On the other hand, if your previous air conditioner broke down sooner than expected, you may want to explore air conditioning options that weren’t available when you last bought one.

Whichever your situation is, you are making the right move by doing research first. Be careful though: Most websites or so-called AC "experts" will merely advise you to purchase a more expensive unit which in this case is a dual-stage air conditioner. It is still up to you to make the decision based on your individual needs and more importantly, your budget. 

Let's start diving into the three most vital factors to consider when purchasing either a single-stage or two-stage air conditioner.

Factors to Consider When Choosing Performance Air Conditioners

Cool and Comfort

A Single Stage air conditioning unit is cooling your home at one capacity: high. This is perfect if you want to quickly get to your desired temperature level as soon as possible, perhaps on a really hot and humid summer day when you walk into your house. It will stay on until it reaches your thermostat setting, and then cycle off automatically only to turn back on once the ambient temperature gets warmer again.

Two-stage air conditioners are considered performance air conditioners and work differently. A two-stage air conditioner's compressor starts in the Low setting, which is equivalent to 60% to 70% of its maximum. This setting suits for milder weather days when you don't need as much cooling. Most of its running time, the setting is on Low so it runs longer and reduces the starts and stops of the unit.

Once it gets too hot outside, this unit will crank up to High, equal to the 100% capacity of a single-stage air-conditioner. It will stay that way until the thermostat in the room is satisfied.

Affordable Pricing

A single-stage air conditioner is significantly more affordable than the two-stage air conditioner. The two-stage air conditioner is more state-of-the-art and complex so the upfront price, labor cost and additional installation charges are significantly higher than the single-stage AC unit.

A single-stage air conditioner in the mid-efficiency range can cost $2,500 to $3,500 including installation, while high-efficiency models can cost $4,000 plus for the hvac equipment and installation costs.

On the other hand, in its mid-level efficiency, a two-stage air conditioner costs between $4,000 to $5,000. While the high-efficiency two-stage units can cost you between $5,000 to $7,000 to purchase the unit and have it installed, not yet including the needed add-ons such as a variable-speed air handler or furnace.

Potential costs such as repair and maintenance of a single-stage and a two-stage air conditioner are also very different. Because of its more complex design, two-stage AC naturally has a larger number of parts and they are not always easy to find in stock. Obviously, the labor cost for repair for the two-stage unit also is higher compared to single-stage.

HVAC Energy Consumption

Since a single-stage air conditioner cools your home at a full blast, it can do the job of chilling your home quickly and will automatically turn off once it reached the thermostat setting. This could mean that there is a considerable amount of energy consumed in starting up and turning off the furnace during the day.

The two-stage air conditioner, however, will consume lesser energy since it takes longer to run and there are fewer times for it to turn on and off.

What most sources will not tell you is that two-stage cooling is not ideal for every home, specifically for larger residences, unless you have a zone system which further complicates the HVAC system.

A house with this kind of system makes it easier to control the temperature in each zone or room individually. Without this, stage one of the two-stage AC blower speed will most likely be insufficient to push the cool air to all places in your home. Unless you're willing to purchase more than one two-stage unit for example, which by the way, is undoubtedly more expensive!

Why Single Stage Is Better Than Two-Stage Air Conditioners

Most homeowners decide to purchase a single-stage air conditioner because it is more practical for their needs. The number one reason is that the up-front cost is lower.

The second factor most people consider whether to choose a single-stage air conditioner over two-stage AC is the size of their home. A smaller to an average residence can effectively be cooled by just a single compressor. It's worked well for 50 years. If it ain't broke, don't fix it. You're just trying to cool your air.

Lastly, but not the least reason why single-stage is more reasonable, is the potential cost of repair and maintenance. A single-stage air conditioner's ease and low cost of repair is a huge advantage.

More complicated equipment such as a two-stage air conditioning unit will definitely have more expensive parts. And these HVAC parts are not always easy to find at local distributors.

Getting them delivered from bigger out-of-town branches may take time and additional courier charges. Let's face it, one of the last things you want to hear when it's blazing out and your AC is down is you have to wait for parts. This rarely happens with a one-stage AC.

Accompanying this problem is looking for a trained technician to fix the two-stage air conditioner. Since it is more high-tech than your regular AC, only a few expert mechanics can understand and repair its issues. And since he may be one-of-a-kind in your area, you may be charged more than your average repairman.

What about the Variable-Speed Air Conditioner?

If you are looking to buy an even more lavish and high-tech air conditioning unit than the two-stage air conditioners, you may want to consider variable-speed air conditioners. Why is it pricier? While the two-stage air conditioner runs on Low at 60% to 70% of the maximum power, variable speed can run at much less capacity: 25% to 30%. This results in longer cycles that can almost last a whole day during the summer season. 

One advantage of this variable-speed air conditioner is it promises better dehumidification of the air in your home. It claims  greater comfort at a lower utility cost.

Any drawback? The amount of needed air conditioning repair of course. And since it is an upgrade to an already expensive two-stage unit, an average variable speed air conditioner ranges from $6,000 to a whopping $10,000.

Single Stage vs Two Stage Conclusion

Don't get sucked in to all the marketing. When the weather turns warm and you're in need for a new HVAC system, don't focus too much on heating and air options. Your main decision is to choose the right contractor. Nothing is more important on the installation of a new HVAC system.

A good contractor will determine the cooling needs of your home and help you find the right type of AC that will cool your air perfectly. And the right AC will probably be the less expensive option.

Take that extra money for a two stage AC and buy a better thermostat or air filter or when you get a new system. Those can improve indoor air quality and you'll be much happier with that kind of upgrade.

You will be happy with any single stage model as long a quality contractor handles the installation. And they won't recommend features that you don't need.

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4 comments on “Single Stage vs Two Stage Air Conditioner | One Should Be Avoided”

  1. Robert,

    Greatly appreciate you sharing your knowledge and expertise. Your information was very helpful. I have a small home and wanted a good unit but was concerned about falling into the technology trap (two stage/variable speed) and buy something that really wasn't going to provide any material benefit and cost more to maintain and repair overall. Thank you!

  2. Robert, thank you for posting this. I thought I was sold on a two stage, but no one can quote me one or get one. I've had a Trane single stage scroll compressor for 23 years before it gave out. Now I'm satisfied with going to a single stage again. Thanks~!

    1. Glad this helped. The more complicated the air conditioner, the more trouble they're having with production. Imagine what it will be like when the AC breaks down the road!

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