Single-Stage vs. Two-Stage Furnace: What’s the Difference?

We’ll be the first to admit that there’s a lot of different furnaces on the market, so we don’t blame you if it gets a little confusing. You may be caught in a whirlwind of HVAC technicians going on and on about a single-stage vs. two-stage furnace, but what in the world does it mean?

It may be tempting to just brush it all off. You probably have other things to worry about, right? But before you do that, our experts at Santa Fe Air made learning the difference between single-stage and two-stage furnaces easy. Keep reading and you’ll become a furnace expert yourself (actually, probably not, but you’ll definitely be more aware). 

What is a single-stage furnace?

We’re not going to bog you down with a whole bunch of definitions all at once. So first, let’s talk about single-stage furnaces. 

A single-stage furnace has a single valve and a single-speed blower motor. You don’t have to know exactly what those are; what you should know is the result of these components. Single-stage furnaces only run on one setting: full speed ahead. Okay, so it doesn’t actually say that, but they’re always running on either 100% capacity or 0%; there’s no inbetween. 

“What’s the problem with that?”

There’s not necessarily a problem, especially if you have the right size furnace for your home. Your house will stay warm (as long as you don’t have furnace issues). 



  • Cheaper to install
  • Has lower repair costs
  • Common in homes

What is a two-stage furnace?

The main reason people turn to two-stage furnaces is because they have energy saving benefits. Of course, you’ll only gain benefits if the furnace is installed properly. 

The valve of a single-stage furnace only has two positions: open and closed. On the other hand, a two-stage furnace has three: open, closed, and partially opened. As a result, two-stage furnaces can run on either high or low capacity. 

The great thing about the two settings is that your furnace can still run on 100% capacity on high, but when it’s not as cold outside, the low setting runs at about 65% capacity. Imagine how much you could save when your furnace isn’t always blowing crazy amounts of heat.

Plus, two-stage furnaces are optimal if you want to get an HVAC zoning system. Zoning systems are a great way to balance out the temperature in your home to get rid of hot zones. 




  • More energy efficient
  • Great for zoning
  • Allows for balanced heating

Santa Fe Air has your furnace needs covered

Deciding between a single-stage vs. two-stage furnace is all about figuring out what’s best for your home. For people in the Kansas City and Johnson County areas, our experienced team of HVAC technicians can help you find the perfect heating solution. Whether you need a furnace installation or a furnace repair, we’re always here to help.

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