Single Stage vs Two Stage Air Conditioner

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Updated September 23, 2022

If you’re looking at the differences between single-stage air conditioners vs two-stage models, there are a few important factors to look at. Depending on your needs, energy efficiency may not be as much of a concern as the initial price, but performance and long-term energy costs come into play for those with bigger cooling needs to have your home reach a certain temperature and bring you comfort, even with the best air conditioner.

KEY TAKEAWAYS:

  • Two-stage AC units are more efficient than single-stage units and have a longer lifespan because they don’t have to work as hard to cool a space.
  • Single-stage AC units offer more than sufficient cooling power for most spaces at a lower price point than two-stage models and will be a good choice for smaller spaces.
  • The lower price point of single-stage units may offset the increased cost of monthly energy bills, which can be significantly more than those of a two-stage unit if they’re used a lot and in larger spaces.

While you’re learning about these two options, read up on the differences between split system air conditioners vs packaged systems. If you’re looking at split systems, you should also take a look at the differences between single split and multi-split air conditioners. These are very different than a gas vs electric air conditioner and inverter vs non-inverter A/C.

What’s the Difference Between Single-Stage Compressor AC Units vs Two-Stage Compressor AC Units?

Single-stage air conditioners and two-stage models differ in a few key ways, the biggest one being the number of compressors they’re built with. Beyond that, efficiency, price point, and performance are all considerations you need to take into account.

Insider Tip

A single-stage AC unit will generally provide enough efficiency and power for those with only seasonal air conditioning needs and average-sized spaces.

Performance

When it comes to cooling power and performance, two-stage models have an advantage over one-stage designs. This is because the two-stage system allows them to work at either 100% power or 75% power, depending on the room conditions, whereas single-stage designs can only run at 100%, compromising efficiency and performance over the long run.

Efficiency

Closely related to performance, two-stage AC units are significantly more efficient than one-stage models due to the fact that they can switch to using less power if the room conditions allow it. This means each compressor works less hard over the lifespan of the unit, which also means two-stage units last longer before a major malfunction. It’s why you’ll want to choose the right central air conditioner.

Cost

A single-stage system comes at significantly lower price points than two-stage models, but there’s a catch. Their much lower efficiency translates to higher energy consumption, so long-term energy costs can be much higher than those of two-stage models. This is less of an issue if you don’t have year-round, constant air conditioning needs, so single-stage units, like the finer 6000 BTU air conditioners, are a less expensive option if you’re only cooling a small space on a seasonal basis.

Warning

Even if you have a small space to cool, a single-stage AC unit may not be sufficiently powerful and efficient enough for year-round cooling without greatly increased energy costs.

F.A.Q.S

Is a two-stage air conditioner worth it if you live somewhere like Florida?

Most likely. If you live in a region that’s consistently hot and humid throughout most of the year, you’ll save money in the long run with a two-stage unit because of its increased efficiency, lower energy usage, and resultant lower energy costs.


Does a two-stage AC run all the time?

No. What a two-stage air conditioner does is use two different compressors — one that runs at 100% power and one that runs at 75% — to vary how hard the unit is working, depending on room conditions.


What’s the difference between a one-stage and two-stage air conditioner?

The main difference is that a single-stage air conditioner has a single compressor that runs at 100% power at all times, while a two-stage model has one full-power compressor and one reduced-power compressor which alternate depending on room conditions, making them more efficient and increasing their lifespan.



STAT: A two-stage AC unit’s second compressor can run at as low as 40% of maximum power but generally runs at around 70-75%. (source)

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