Variable-Speed HVAC vs Single-Stage HVAC System
Discover the differences between the opposite ends of the HVAC system spectrum to help you decide what residential heating and cooling system is right for your home.
By Anne Fonda
Key takeaways, or the TL; DR of this article
Single-stage HVAC systems are at the low end as far as upfront cost and energy efficiency, and cost more to operate. Variable-speed HVAC systems are at the high end of upfront cost and energy efficiency but can deliver long-term energy savings, as well as deliver more precise comfort and humidity control.
How does a variable-speed system work?
Variable speed systems change speeds to adapt to changing conditions, providing precise heating or cooling while optimizing energy efficiency. A variable speed system takes into account the setpoint temperature on your thermostat, the indoor and outdoor temperatures, the humidity inside your home, and the rate of temperature change in your home, to determine the appropriate output.
They use the minimum amount of energy to reach and maintain your set temperature. Units can run anywhere from 25% to 100% capacity. The most energy-efficient variable-speed HVAC systems have an outdoor unit with a variable-speed compressor and an indoor unit with a variable-speed blower motor.
What are the benefits of a variable-speed AC unit or heat pump?
A variable-speed air conditioner or variable-speed heat pump has 3 main benefits:
- Enhanced comfort
- Superior humidity control
- Superior energy efficiency and related cost savings
Let’s take a look.
Enhanced comfort
Variable-speed systems provide consistent comfort with precise temperature control. This helps keep you comfortable, no matter what the outdoor temperature is.
Superior humidity control
Our variable-speed units provide superior humidity control as they cool your home, even allowing you to adjust the desired humidity from your thermostat in the same way that you adjust the desired temperature. This can be crucial if you live in an area where the summers are hot and humid. High indoor humidity can lead to decreased comfort and potential damage to your home.
Superior energy efficiency and related cost savings
Superior energy efficiency generally leads to reduced energy consumption. And in general, reduced consumption will lead to cost savings on your utility bills. Your exact energy and cost savings will depend on the system components you install, utility rates in your area, your usage habits, and more. Maximize your savings by utilizing a smart thermostat.
“By delivering the precise capacity your home needs, Trane’s variable-speed units maintain much tighter temperature control, which has been field-verified to be within 0.25°F of the thermostat set point, yielding optimal comfort.
By always delivering the minimum capacity that your home needs (no more and no less) instead of cycling on and off, the unit runs at significantly higher operational efficiency and a lower sound level,”
– Mark Woodruff, Senior Product Manager, Ducted Outdoors
What are the drawbacks of a variable-speed HVAC system?
The main drawback we hear about is that a variable-speed system comes with a higher price tag. That’s one reason we offer special 0% HVAC financing through Wells Fargo and selected dealers. We want you to be able to invest in your long-term comfort without breaking the bank.
How does a single-stage HVAC system work?
Single-stage, or single-speed, HVAC systems are basic systems. They have two settings: on or off, which means they run at full capacity or not at all. These systems work at full speed to cool down your home and then shut off. They may come on again quickly on hot summer days.
Because of the frequent switch from on to off, and because they can only operate at 100% max speed, single-stage systems are usually the most expensive to operate.
What are the benefits of a single-stage air conditioner or heat pump?
A single-stage HVAC system offers a heating and cooling solution for budget-conscious homeowners. A single-stage AC unit or heat pump will be more affordable upfront than variable-speed units.
What are the drawbacks of a single-stage HVAC system?
“Single-stage systems are the tried-and-true workhorses of the HVAC industry and represent a high percentage of what most homes have today. What they give up in energy efficiency, they make up for with a lower purchase price. Trade-offs include that they do not have the more advanced dehumidification capabilities or low sound output of a variable speed system, nor can they achieve the same high levels of efficiency.” Woodruff said.
A new middle-ground HVAC system
Trane recently introduced the 17 Multi-Speed Air Conditioner with WeatherGuard™ as well as the 17 Multi-Speed Heat Pump with WeatherGuard™. These units have many of the benefits of a variable-speed system without the complexity and premium price tag.
You get more heating and cooling capacity at extreme temperatures and enhanced humidity control. Because the system delivers a more appropriate amount of capacity during mild conditions, it will run longer, using less power, removing more humidity, and maintaining airflow throughout the home. This delivers better home comfort and reduces hot and cold spots throughout your home.
“These new Multi-Speed units are a great mid-point option between a traditional two-stage and a fully variable speed system. Homeowners are able to achieve more efficiency, comfort, and reliability than they could with a traditional two-stage system, without the complexity and additional upfront cost of a variable speed system. Factor in the benefit of a universal control compatibility with a 24V thermostat, it’s a real win for homeowners!”
-Chelsea Hudson, Product Manager, Ducted Variable Speed Outdoor
Work with the HVAC experts
Work with your local Trane dealer to select the outdoor air conditioner or heat pump and the indoor furnace or air handler. They can make sure the system components are compatible and offer you the energy efficiency and comfort level you desire. Explore our savings and offers page to see all the financial incentives available to you.
Anne Fonda, Content Writer
A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.
She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.
When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.
Expert review by Mark Woodruff, Senior Product Manager, Ducted Outdoor
Related Articles
