Single-Stage vs. Two-Stage Air Conditioner: 4 Common Questions Answered

Posted 06-24-14 in Air Conditioning

Single state vs two stage air conditioner questionsSo, you’ve seen the signs that you need a new air conditioner.  And you’re researching online or talking to AC contractors, and you’ve heard about “single-stage air conditioners” and “two-stage air conditioners.”

We’re sure you have lots of questions, like:

  1. “What’s the difference between a single-stage and a two-stage air conditioner?”
  2. “What are benefits of getting the two-stage over the single-stage air conditioner?”
  3. “What’s the price difference between the two-stage and the single-stage air conditioner?”
  4. “Which one should I pick?”

We’ll answers those questions in this article.

1) “What’s the difference between a single-stage and a two-stage air conditioner?”

The main difference between the two types of ACs is the type of compressor they use (the part of the AC that compresses the refrigerant).

A single-stage air conditioner’s compressor only works one level of operation— cooling your home at full blast.

A two-stage air conditioner’s compressor works at two levels of operations:

  • High for hot summer days (the equivalent of full blast for single-stage ACs)
  • Low for milder days when you don’t need as much cooling

Basically, a two-stage air conditioner will, by default, run on the lower setting until it gets too hot outside. Then it runs on the high setting to make sure you stay comfortable.

2) “What are the benefits of getting the two-stage over the single-stage air conditioner?”

The two main benefits of getting the two-stage air conditioner are:

  • Greater energy efficiency (meaning lower energy bills)
  • Greater comfort

Let’s explain why.

Greater energy efficiency
Like a car, an air conditioner costs less to operate when it turns on and off less often. Each time the AC starts up, it costs more because of the greater energy needed to start up.

A single-stage air conditioner turns on and off more frequently because it can only cool at one speed, then turn off once it reaches your thermostat setting.

But the two-stage air conditioner can meet your cooling needs about 80% of the time with its low setting, meaning it will run more often without as many starts and stops.

Greater comfort
Because the two-stage air conditioner runs more often, it will provide more even cooling and can remove twice as much moisture/humidity from your air. And in the south, you know the pain of outrageously high humidity.

3) “What’s the price difference between the two-stage and the single-stage air conditioner?”

Two-stage air conditioners cost more than single stage-air conditioners. By how much? It depends on other factors, such as the SEER rating of each unit. Contact us for an estimate to get an exact comparison.

4) “Which one should I get?”

It depends on two major factors:


To learn more about single-stage vs. two-stage air conditioners and which one is right for you, ask one of our experts for help.

Coolray is your Atlanta-area home comfort expert with specialists in heating, air conditioning, air quality and plumbing. Have more questions? We’d be happy to help – just contact us online.

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