By Anne Fonda
Single-stage HVAC systems work at full speed to warm or cool your home. Once it has reached the set temperature, the system shuts off. Then, once the temperature in your home rises or falls a couple of degrees, the system turns on again. A single-stage air conditioner may have trouble with consistent dehumidification and can result in hot and cold spots as well.
Single-stage AC units and furnaces cost less than other comparable units because of their simpler technology. However, because of the frequent on-off cycle, a single-stage HVAC system can be the most expensive to operate.
What is the difference between 1-and-2-stage HVAC? Simple. Instead of having just one stage where it operates at full power or not at all, a 2-stage air conditioner, heat pump, or furnace has two heating and cooling stages. It can operate at 65% or 100% capacity.
On a day with milder outdoor temperatures, the system would run at a lower speed most of the time. During a heat wave or bitterly cold temperatures. The system would run at 100% capacity most of the time.
The two stages give you a more consistent temperature. In general, a two-stage system will be more energy efficient than a single-stage system.
What is the cost difference between single-stage and two-stage AC units?
A two-stage system will cost more than a single-stage system upfront. But the energy savings and lower utility bills can help make up the difference.
The increased comfort level may also make a two-stage system worth the extra money.
A variable-speed system is a third option for AC units and heat pumps. It’s the most energy-efficient HVAC system, but is also more expensive upfront. In American Standard units, the variable speed system has more than 700 speeds to offer you optimal indoor temperature and humidity control, even on the hottest days.
Variable-speed units can run anywhere from 25% to 100% capacity. This provides you with precise heating and cooling temperature control. Variable-speed ACs and heat pumps may run longer at lower speeds, but use less energy.
Need more information on a single-stage vs 2-stage furnace or air conditioner vs a variable speed system? Contact your local American Standard dealer for expert product recommendations tailored to your home, climate, and budget.
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
In HVAC equipment, the word stages refers to the heating or cooling capability. The stage may also be referred to as speed – as in single-speed, two-speed, and variable-speed. Two stages simply means the unit has two heating stages or two cooling stages. Low speed, or first stage, might be running at 65% capacity, while the second stage, or second speed would be at 100% capacity.
Variable-speed motors allow HVAC systems to operate at a variety of different speeds, as opposed to one consistent pace.
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