Single‑Stage vs. Two‑Stage Gas Furnace: Which is Better For My Portland Home?

If you’re considering a new furnace, you may wonder whether you’ll be okay with a single-stage unit or if you should pay a little more for a two-stage furnace.

Our recommendation? We suggest that Portland homeowners go with a two-stage gas furnace. A two-stage furnace offers many benefits over a single-stage furnace, including:

  • Lower energy costs
  • Less noise
  • Improved indoor comfort
  • Better indoor air quality
  • Longer equipment lifespan

We’ll go into more detail about each of these benefits later. But first, we’ll explain what the “stages” mean and the difference between a single- and two-stage gas furnace.


Want a professional recommendation for your new furnace? Four Seasons’ comfort specialists can help you find the right furnace for your home and budget. We offer a wide range of systems for you to choose from, from single-stage to two-stage high-efficiency furnaces.

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What Are Furnace Stages?

Two-stage gas furnaces are more efficient than single-stage gas furnaces. / Source: Coleman

Stages refer to the different heating modes of a gas furnace.

A single-stage furnace only operates at one fixed heating mode (100% capacity). When the thermostat calls for heat, a single-stage furnace will always run at full blast until your home reaches the desired temperature.

On the other hand, a two-stage furnace has two heating modes: high (100% capacity) and low (60–70% capacity, depending on the model). A two-stage furnace will switch between high and low modes depending on the heat called for by the thermostat. Learn more in What is a 2-Stage Furnace?

The low mode is advantageous on relatively moderate days when heat demand is less. Because the low mode allows a two-stage furnace to conserve energy during mild weather, it provides the comfort and cost-saving benefits we’ll explore below.

The Benefits of a Two-Stage Furnace

Compared to a single-stage furnace, a two-stage furnace provides benefits such as:

Lower energy costs:

When a two-stage furnace runs on low mode, it conserves energy. The less energy your furnace uses, the lower your monthly energy bills will be.

Less noise:

A furnace is at its loudest when it operates at 100% capacity. The low mode allows a two-stage furnace to run at a lower capacity, which helps to reduce noise.

Improved indoor comfort:

Single-stage furnaces can produce temperature fluctuations as high as 4° F because they have shorter heating cycles. Because two-stage furnaces have longer heating cycles in low mode, they provide more consistent temperatures (with temperature fluctuations of only 2° F).

Better indoor air quality:

Like the benefit above, the longer heating cycles of a two-stage furnace can also help clean your home’s air. The longer your furnace runs, the more pollutants the air filter can catch.

Longer equipment lifespan:

A furnace that runs non-stop at 100% capacity is more likely to wear out faster. During mild winter days, a two-stage furnace can run at a lower capacity which will help prolong the lifespan of the equipment.

If You Want Highest Energy Savings and Premium Comfort, Get a Modulating Furnace

Modulating gas furnaces are energy efficient and provide great comfort.

A modulating furnace can run at any capacity from 40% to 100%. It gradually ramps up or down based on the heating demand, making it even more energy-efficient than a two-stage furnace.

However, the technology that allows a modulating furnace to operate at variable capacities raises the cost of the equipment considerably. We recommend that you consult with a heating expert to see if a modulating furnace makes sense for your home and budget.

Want a Furnace Recommendation From a Portland Pro?

Four Seasons heating technicians are ready to help you install a two-stage high-efficiency gas furnace.

Request appointment today

Our comfort specialists have one goal: to help you choose the perfect heating system for your home and budget. We won’t sell you any equipment you don’t need, and we always provide upfront, honest prices.

When it comes time to install your new furnace, you can count on our solid guarantees and exceptional customer service during every step of the project. To learn more about what to expect when you hire us, visit our furnace installation page.


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