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January 24, 2023

Advantages and Disadvantages of Two-Stage Furnaces

Two Stage Furnace - LG Home Comfort

You may have heard of two-stage furnaces, but do you know what they are? Two-stage furnaces are popular for homeowners looking to improve their home heating system. But are they worth it?

In this article, we will look closer at the advantages and disadvantages of this type of furnace to help you decide whether to invest in one for your home.

What Is a Single-Stage Furnace?

Single-stage furnaces offer one setting when it comes to heat—the high setting. When it starts to operate, it will run at maximum power until it reaches the highest temperature. This is regardless of the outdoor temperatures or specific areas in your home.

A single-stage furnace works best in mild winters because it continuously turns on and off as temperatures fluctuate.

What Is a 2 Stage Furnace?

A two-stage furnace runs at low capacity during mild winter days. It switches to high capacity when greater demand for warmth is needed. Most of the time, it runs at a lower speed, slowly increasing according to the desired temperature to meet your home’s heating needs. This improves energy efficiency since the furnace does not always need to run at full power. It also helps create steadier temperatures in your home, as it is running longer but at lower speeds.

What Is the Difference Between Single-Stage and Two-Stage Furnaces?

The most notable difference between single-stage and two-stage furnaces is their cost. Two-stage furnaces are more expensive due to their two motors and other components. Single-stage models use one and are also cheaper to repair.

But two-stage furnaces may have lower energy costs. Here’s why:

As mentioned, a single-stage furnace operates at only one setting, which is full power, when there is a need for warmth. It blasts out as much hot air as possible, according to the thermostat. This means that during the coldest months, it disperses the most amount of energy it can. This makes single-stage furnaces cost more on electric bills.

Meanwhile, a two-stage furnace has two settings: low and high power. This allows more precision in how it responds to temperature changes. It gradually increases the heat from a lower temperature, costing you lower energy bills, and keeps your space more consistently heated.

2 Stage Furnace Advantages

Here are six major advantages of having a two-stage furnace in your home:

#1: Electronic Commutated Motors (ECMs) Are Low-Maintenance

ECMs (electronic commutated motors) are a two-stage furnace’s main features. Since these furnaces cycle on and off less frequently, there is less stress on the system. This means your furnace will have fewer breakdowns and extended operating life.

#2: Energy Efficient

Two-stage furnaces are well known for their energy-efficient features. By running at low capacity most of the time, they use much less energy than single-stage furnaces and maintain good air circulation.

#3: Reduce Operating Costs

The energy consumption of two-stage furnaces is lesser so this helps reduce your operating costs over time. They also provide consistent temperatures throughout your home without wasting energy or overworking your HVAC system. Plus, you will not have to worry about repairs or frequent furnace replacement costs since they don’t get damaged easily.

#4: Quieter Operation

Two-stage furnaces are much quieter than single-stage furnaces due to their slower operating speeds and quieter ECMs. Single-stage furnaces produce loud noises when they turn on and off. But with a two-stage furnace, these noises are much less noticeable and will not disrupt your day as much as they would with a single-stage furnace.

#5: More Even Temperatures

The two-speed operation of a two-stage furnace allows it to maintain even more temperatures in your home. Rather than producing large temperature fluctuations throughout your house, the two-stage system will keep temperatures steady and consistent over long periods. This provides added comfort while keeping energy costs down. And since this increases comfort levels in all areas of your house, it also reduces drafts that can form in colder areas like near windows or doors.

#6: Improved Indoor Air Quality

The improved airflow from two-stage furnaces can help keep dust and other irritants from circulating through your living space. This can help improve indoor air quality and reduce allergy symptoms for your family.

2 Stage Furnace Disadvantages

Knowing the potential disadvantages of this furnace can help you decide when considering it for your home. Here are the 2 stage furnace disadvantages:

#1: Higher Cost

The initial expense is the most significant disadvantage of installing a two-stage furnace. This furnace typically costs several hundred to thousand dollars more than a single-stage unit. This is because of the increased complexity of the operating system and the additional components needed for proper operation. Although it will be functional for a longer period and assures energy savings and comfort, the high installation cost can be a major setback.

In addition, 2 stage furnaces require special filters for optimal performance. Depending on the manufacturer, these filters may need to be replaced more frequently than single-stage filters, which can add to overall costs over time.

#2: More Difficult and Expensive Repair

Because two-stage furnaces are more complex than their single-stage counterparts, they tend to require more specialized parts for repairs or maintenance. This can lead to higher repair costs and longer wait times before getting back up and running again.

Additionally, because two-stage furnaces use multiple burners, they generate more heat than single-stage models. So, any repair work needs greater caution as it requires handling higher temperatures to complete the job correctly.

Is a 2 Stage Furnace Worth it?

A two-stage furnace is worth considering if you are building a new home or updating existing HVAC equipment. It is ideal for a large, multi-story home for its greater efficiency and improved comfort level. As mentioned, it runs at either low or high power, depending on the thermostat’s temperature settings.

Additionally, this furnace type will mean higher energy savings and greater comfort levels. These make a two stage furnace worth it as a long-term investment if you seek these advantages.


Whether or not to invest in a 2-Stage furnace depends on personal preference. Consider the pros and cons mentioned above to help you decide. Remember that improved efficiency and more consistent temperatures throughout your home are excellent reasons why upgrading from an old single-stage unit might be worth it.

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