Choosing the Best Heating and Cooling System: A Guide for You and Your Clients

As you shop for a new heating and cooling system for a home, it’s easy to get overwhelmed. Single-stage? Two-stage? Variable speed? The options are plentiful, and the lingo can leave you feeling a bit lost. Given that you’re putting a solid chunk of money on the line, how can you and your clients possibly choose the best system for your homes?

Let’s take a moment to break down the differences between systems. We’ll go through the biggest variables — price, efficiency, noise, humidity control and overall air quality — so you can choose accordingly.


When it comes to efficiency, the Seasonal Energy Efficiency Ratio (SEER) is your go-to. This measures how much a cooling system puts out for each unit of energy it consumes. The higher the SEER rating, the more efficiently the system performs.

Single-stage systems are the least efficient of the bunch. As the name suggests, they have one “on” setting. The only option is for the system to run at 100% capacity, regardless of whether conditions really demand it. So, these systems frequently use more energy than necessary.

Two-stage systems offer some efficiency improvements because they have two settings — high and low. On more mild days, the second setting allows the system to run at a lower, reduced level of operation. These two-stage units typically have a SEER rating between 16 and 18.

Variable speed systems are the most efficient systems available. They can operate at many different levels specific to your home, down to as low as 20% capacity, and they boast the highest SEER ratings at 25 or higher.

Humidity Control

These different types of systems offer varying levels of humidity control as well. This, of course, is important to help prevent the growth of mold and mildew. In a nutshell, when your unit is running and producing a consistent flow, humidity is reduced. The longer it runs, the greater the reduction in humidity.

Single-stage systems are designed to stop once they reach the desired temperature. Thus, they actually spend the least time running and offer the least humidity reduction. A two-stage system will actually run longer, which helps cut humidity levels more. A variable speed system ultimately takes the cake. These systems allow for constant air flow, decreasing the humidity most effectively.


When it comes to cost, it’s important to consider two factors — the purchase price and the cost of operation long-term. A single- stage system boasts the most affordable up front cost, but will cost the most to operate long-term. A two-stage system will be more expensive up front, but will cost less to operate than a single-stage unit. And — you guessed it — a variable speed system will have the heftiest price tag but see the biggest benefits in term of operating costs, along with the perks of efficiency and indoor comfort.

Do keep in mind, more efficient systems often qualify for with tax credits, so that can help with costs as well. The credits for 2017 are as follows:

  • Federal Tax Credits – $300 for split systems, SEER 15 or higher
  • Arizona Public Service – $200 for SEER 15 or higher
  • Salt River Project – $400-800 for variable speed systems

Air Quality

When considering air quality, the differences between the different types of systems is a bit like the story with humidity control. The longer the unit runs, the better the air quality too. Why? The more air that passes through the filter, the greater the opportunity to catch all those undesirable bits of dust, debris and allergens. On top of that, continual air movement can minimize hot and cold spots within your home. Given this, variable speed systems are able to provide the most impressive levels of air quality and comfort (and single-stage systems the least).

Noise Level

This factor can easily get overlooked when considering a system, but it’s good to realize what you’re getting into in terms of noise with each type of system.

Because they only operate at full capacity, single-stage units are the noisiest of the bunch. They are notorious for a noticeably loud start and stop. Two-stage systems offer a bit of reduction in noise. Variable speed systems can operate at a much lower, less noisy level. Unlike single-stage and two-stage systems, they do not produce the noisy kick in whenever airflow is needed and instead can run at the low background level much of the time.


In many ways, the world of heating and cooling systems is actually relatively straightforward. Costlier variable speed systems offer more in efficiency, energy savings, humidity control, air quality and noise reduction. Less costly single and two-stage systems provide less in these arenas.

It ultimately comes down to your budget and desires and expectations for your home. Variable systems are a great option for those who have a more sizable budget and a desire to make a greater investment in the long-term future of their home. For many homeowners wanting some flexibility and efficiency at a more affordable cost, two-stage systems can be helpful. If you’re after the absolutely least expensive up-front cost, single-stage systems are the route.

Latest Articles