Single-Stage HVAC vs. Two-Stage HVAC: Key Differences

If you’re in the market to upgrade your cooling system, you’ll likely come across single-stage and two-stage HVAC systems. So, how do you know which one to choose? Factors like your budget, the size of your home, and your particular cooling needs can help you zero in on the ideal option for your unique situation. To help you with your decision, we’ve compared single-stage HVAC units to their two-stage counterparts below.

Single-Stage vs. Two-Stage HVAC System: Key Differences

Single-stage HVAC systems only have one speed, and they’re the most common type of HVAC system used in homes. Two-stage HVAC systems have both a high and a low speed, and they automatically move into high speed if your home isn’t at the temperature set on the thermostat. Two-stage units are quieter and more energy efficient than single-stage units, but single-stage units cost less up front and are less costly to repair.

What Is a Single-Stage HVAC System?

A single-stage HVAC system is the most common type of air conditioner available, and it has only one mode or speed. Once you install a single-stage HVAC unit, you can expect it to continually turn on or off throughout the day, depending on the temperature outside. It will run at full blast or 100% capacity until it reaches the desired temperature. 

Best for: 

• Smaller homes 

• Homeowners who are on a budget

• Those who are less concerned about efficiency and noise

Pros of Single-Stage HVAC Systems

If you’re seeking a budget-friendly HVAC solution, a single-stage air conditioner may meet your needs. Not only is it less expensive up front, but it’s also cheaper to maintain and repair. A single-stage HVAC system is also faster and easier to install due to its smaller size and lighter weight. 

Cons of Single-Stage HVAC Systems

The greatest drawback of a single-stage HVAC system is its inefficiency. Since it turns on and off many times throughout the day, it can waste a great deal of energy and, in turn, increase your utility bill. A single-stage unit may also be very noisy since it’s constantly running at full capacity. In addition, you might need to replace it sooner than you’d like to.

What Is a Two-Stage HVAC System?

A two-stage HVAC system operates on two modes or speeds: high and low. It will kick into high gear if your home is much warmer than the temperature outside. If the temperature in your home is similar to the temperature outside, however, it will run at a low speed. In most cases, a two-stage HVAC system spends the majority of its time on the lower setting, only running at 60% or 70% capacity.

Best for:

• Larger homes

• Homeowners who prioritize energy efficiency 

• Those who are concerned about air quality and allergies 

Pros of Two-Stage HVAC System

Energy efficiency is the most notable advantage of a two-stage model. Since it can run on low or high mode, it uses far less energy, leading to better temperature control and lower utility bills. It also has a higher SEER (Seasonal Energy Efficiency Ratio) rating. A two-stage HVAC system can also operate fairly quietly, allowing for a more relaxing environment for you and your family. 

Cons of Two-Stage HVAC System

While a two-stage HVAC system is very energy-efficient, it comes with a higher up-front cost that may not be in every homeowner’s budget. It will also take longer to install due to its heavier size and the complexity of the two modes. A two-stage HVAC system will be more expensive when you need an AC repair company.

Single-Stage vs.Two-Stage HVAC Systems Compared

When looking into single-stage versus two-stage HVAC systems, there are a few things to consider before reaching out to a local air conditioner installer. Since this is a long-term investment, you should weigh the pros and cons of each option to determine the best fit for you and your home. Below, we’ll take a look at which system comes out on top for up-front cost, energy efficiency, noise, air quality, and life span.

Up-Front Cost: Single-Stage 

The up-front cost of an AC unit is usually a major concern for most homeowners. In this case, a single-stage HVAC system will be less costly than a two-stage one. On average, a two-stage system can run about 30% more, so you could be spending anywhere from $500 to $2,500 up front. 

The extra money for a two-stage HVAC may be worth it if you’re looking for a quieter, more efficient one that may lower utility bills–especially if you live in a warmer climate that will get a lot of use out of the system. 

Energy Efficiency: Two-Stage 

As far as energy efficiency is concerned, a two-stage HVAC system takes the cake. Compared to a single-stage unit that always runs at 100% capacity, a two-stage unit only runs at 60% to 70% capacity. It won’t operate at high speeds unless it really needs to.

Quietest: Two-Stage 

At the end of the day, most homeowners appreciate a peaceful, quiet space. If high noise levels are an issue for you, you should know that a two-stage HVAC system is much quieter than its single-stage counterpart. Sometimes, you may even forget it’s running.

Indoor Air Quality: Two-Stage 

Air quality is an important consideration if you’d like to keep yourself and your family healthy. Thanks to its improved airflow, a two-stage HVAC system can help prevent dust and other irritants from circulating throughout your home, along with routine air duct cleaning. It’s the best choice if you hope to improve your indoor air quality and keep allergy symptoms to a minimum. 

Life Span: Two-Stage 

On average, an HVAC unit lasts between 15 to 20 years. Due to their higher quality parts, two-stage HVAC systems tend to last closer to 20 years. This is particularly true if you invest in a unit from a reputable manufacturer and get it serviced on a regular basis.