Single-Stage, Two-Stage, and Variable-Speed HVAC Systems

If you’re thinking about HVAC replacement, you’re smart to be doing some research. Today, we’ll answer a question we get a lot – What’s the difference between single-stage, two-stage, and variable-speed HVAC systems?

April 16, 2024

If you have an aging central air conditioner that just isn’t keeping your home as comfortable as it should, it may be time to start thinking about AC replacement. Or maybe consider upgrading to a heat pump system. 

One of the biggest decisions you need to make with HVAC system replacement is whether you will get a single-stage system, two-stage system, or variable-speed system. Think of these systems as good, better, and best.

Which system you choose will impact your overall comfort and your wallet. To help you make the decision about which system is best for your home, we’ll explain a bit about each type.

Let’s get started.

What is a Single-Stage System?

A single-stage HVAC system is where it all started. With this system, it’s either on or it’s off. That means it runs 100% full blast when it’s on, cooling your home to the temperature you set. Then it shuts off. Then it comes back on full blast when the temperature rises.

A single-stage air conditioner can be a good option if you are budget-conscious. American Standard offers single-stage AC units and heat pumps with efficiencies ranging between 13.4 and 1613-15 SEER2.

What is a Two-Stage System?

A two-stage system is the next step up in HVAC systems. Two-stage systems have a low setting and a high setting. The HVAC units will start on the lower setting and kick into high gear if it’s not cooling as fast as it should.

Once the desired temperature is reached, the system settles back into low to maintain comfort. A 2-stage air conditioning unit uses less energy than a single-stage system. This system will also offer more consistent temperatures and humidity control 

A 2-stage AC or 2-stage heat pump has a 2-stage compressor. Then, of course, there is a 2-stage fan that can run on high or low as well. 

A two-stage system can be a nice upgrade from a single-stage system, offering a higher level of comfort and saving on energy costs. American Standard offers the Gold 16 two-stage AC unit and Gold 16 heat pump.

What is a Variable-Speed System?

A variable-speed HVAC system is the top tier of HVAC systems. It offers superior energy efficiency and is a serious upgrade from either a single-stage system or a two-stage system. That’s because a variable-speed air conditioner or variable-speed heat pump can offer precise cooling and heating. 

The system will run at whatever speed is necessary to reach the desired temperature. Then, the system will run at the lowest speed nearly constantly to maintain a consistent temperature and maximize your comfort level. A variable-speed system can run at anywhere from 25%-100% full capacity, based on the outdoor temperature, indoor temperature, humidity levels, and the temperature setting on your thermostat. 

The slower the air moves through your variable-speed air conditioning system in the summer, the more humidity is removed. This means you may be able to set the thermostat at a higher temperature than you could with your old system.

In the winter, variable-stage heating can keep you warm and cozy no matter how cold it is outside.

Benefits of an American Standard Variable-Speed System

We highly recommend a variable-speed HVAC system because of all the benefits it offers. Those include:

  • Superior energy efficiency
  • Superior comfort
  • Up to 750 compressor stages 
  • Up to 55% savings on energy costs
  • Quieter operation on lower speeds when compared to a single-stage unit
  • Compatible with HVAC zoning systems for precise temperature control in every room of your home
  • Compatible with the AccuLink™ Communicating System

American Standard offers several variable-speed air conditioners ranging from 17  to 21.5 SEER2 which can pair with Platinum 2-stage furnaces as well as the Platinum 95 gas furnace with an AFUE of up to 97%. We have several variable-speed heat pumps to choose from with a range of SEER2/HSPF2 ratings.

For optimal efficiency in both heating and cooling with any system, you would need a matched system where the heating and cooling units are paired to match in capacity and efficiency. And pair that system with a communicating programmable or smart thermostat, and you increase your energy efficiency even further.

Which HVAC System is Right for Your Home?

Which system is right for your home will come down to how you feel about energy efficiency, sustainability, and your budget. The more efficient an HVAC system is, the more it will cost upfront. More efficient systems also have the bonus of improved comfort and temperature control.

But those upfront costs may be balanced out in the future by reduced energy costs over the next 15 years or so. We would suggest getting the most efficient HVAC system you can comfortably afford. Many dealers offer financing that allows you to make monthly payments.

You should be aware of federal tax credits, rebates, and other offers that can help offset the purchase price of qualified HVAC systems. 

American Standard: Built to Higher Standard

Whether you choose a heat pump system or a gas furnace with AC, American Standard has you covered. We engineer heating and cooling products to a higher standard to provide you with energy-efficient and durable systems you can count on. We’re recognized in the industry for superior products and owner satisfaction.

Consult with HVAC Experts for Advice

Do you need to schedule a quote for HVAC replacement? Find a local American Standard dealer near you who can provide product recommendations and expert installation. For over 100 years, we’ve designed and manufactured some of the most awarded, well-engineered heating and cooling equipment and earned a reputation for doing things right.

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