There are lots of choices to make when you are upgrading, replacing, or installing a new air conditioning system in your home. And all those choices can influence how efficient your new AC is and how much it costs to run. One important choice is whether to opt for a single-stage vs a two-stage air conditioner system.
What Are Single Stage and Two Stage Air Conditioning Systems?
All AC systems have a component called a compressor. The compressor is responsible for controlling the speed at which the refrigerant flows and the amount of power of the system.
A standard central air conditioner has a single stage compressor. This means the air conditioner has one power-on modes and one power-off mode. When it is on, it is operating at 100% power and capacity, or it’s turned off.
With a two stage AC system, the compressor has an extra setting it can use when 100% power isn’t required. Generally, this second setting has the AC operating at around 65% to 70% of its full capability.
How Do the Two Systems Compare?
The main benefit of two stage AC is that it provides an extra option that kicks in when the full 100% capacity isn’t needed. For instance, if your thermostat is set to 75 degrees, the air conditioner might run at full power when the indoor temperature is at 78 degrees or higher. Once the indoor air cools down to 76 to 77 degrees, it switches to the second stage to finish cooling to 75 degrees.
Two stage AC provides a couple advantages:
- The system uses less energy in the second stage mode. Overall, two stage systems have lower energy use than single stage systems.
- Because the compressor is operating below 100% some of the time, it can add to the lifespan compared to the alternative compressor.
In contrast, single stage AC uses more energy, meaning your energy bills are higher. This is partially offset by the fact that these AC systems have lower upfront costs. On the other hand, two stage AC systems cost more upfront, but you’ll likely recoup that extra cost through energy savings over the life of the system.
A minor difference between single stage and two stage AC systems is the noise factor: All modern AC systems are quieter than older models. But there can be a significant difference between single stage and two stage systems as well: They sound much the same in full-power mode, but two stage systems are much quieter when in the low settings.
What Is Variable Speed Air Conditioning?
Two stage AC systems are more energy efficient than single stage systems, but variable systems are top-of-the-line in terms of power, efficiency, and energy savings.
Single stage and two stage systems have either one or two power settings. But variable speed AC systems have literally thousands of them. In fact, it’s more accurate to say that a variable speed air conditioner operates along a power spectrum, rather than having distinct settings.
Variable speed air conditioning systems use what’s called inverter technology. This tech lets the system adjust its own power settings on the fly, rather than switching on and off based on thermostat settings. This means a variable speed air conditioner only ever uses just as much power as is needed to consistently reach and maintain the right temperature.
This makes variable AC the leader when it comes to energy efficiency. Variable speed air conditioners also offer greater comfort because their dynamic power usage lets them maintain a consistent temperature.
Single Stage vs Two Stage vs Variable AC: Which Should You Choose?
Budget: Single stage air conditioning has the lowest purchase and installation costs of the three different types of AC systems. Variable AC systems have the highest purchase and installation costs, while two stage AC is the in-between option.
Is your budget for a new system at the lower end of the scale? A single stage air conditioner is the best option. If your budget is higher, it’s cost-effective to opt for a two stage or variable system. Even though the purchase price is higher, you’ll recoup most or all the extra money over time, thanks to reduced energy consumption.
Cooling Power and Efficiency: Even though single stage AC is a more budget-friendly option, you don’t necessarily have to compromise when it comes to cooling power. As long as your air conditioner is the right size for your home and the installation is performed correctly, you’ll have plenty of cooling power.
The main difference isn’t in terms of cooling power as much as it is energy efficiency. Two stage AC systems are more efficient at using energy than the alternative. And variable AC is even more efficient than both single and two stage systems. If energy efficiency is the most important factor for you and your budget allows it, then a variable speed AC unit is the way to go.
Pro Tip: Whichever kind of air conditioner you get, the priorities are to make sure it’s installed by professionals and sized correctly for your home. Even if you buy the best possible variable speed AC, it can’t operate efficiently if it’s either too large, poorly installed, or too small for your space.
Noise: If the amount of noise your central AC makes is an important factor for you, then you’ll want to choose a two stage or variable speed system. Both are quieter overall than a single stage AC.
Make the Right AC Choice for Your Home: Call CW Service Pros for Professional Advice
Interested in an air conditioner upgrade or a necessary replacement? Making the right choice with your new AC installation can be challenging because it’s crucial to get the right size and power level for your home. When you have CW Service Pros on your side, making the right choice is easy. We’ll help you at every step, so you can pick the best system for your home, family, and budget. Plus, we can perform the HVAC system installation, minor or major AC repairs, and preventive maintenance on AC units too!