2-Stage Furnace Disadvantages? (Ultimate Furnace Guide)

Upgraded Home Team
by Upgraded Home Team

During certain times of the year, relying on your furnace is a must if you want to remain comfortable. If your old furnace breaks down, replacing it is a priority. While looking for a replacement, you may eventually stumble upon 2-stage furnaces.

Should you choose to add a 2-stage furnace to your home? A closer look at the qualities of a 2-stage furnace will tell you that it’s probably not worth the money.

Among the more notable 2-stage furnace disadvantages is a significantly higher upfront cost relative to single-stage furnaces. Furthermore, 2-stage furnaces tend to use more electricity so you’re likely not saving that much money in the long run. You’ll also find that repairing a 2-stage furnace will often cost more money.

New furnaces are significant investments. You have to be certain that you’re purchasing the right one for your home. See if the disadvantages that come with using a 2-stage furnace are deal-breakers for you by reading on.

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What Is A 2-Stage Furnace?

2-stage heating furnaces are designed to offer two types of heating. That ability to provide different levels of heat is the main selling point for this kind of home appliance.

You can opt for high-level heating and that means the appliance’s output will match its full rated capacity. Homeowners also have the option of using the 2-stage furnace at a lower setting. When it’s set to that lower level, the output of the furnace will reach around 80 percent of its rated capacity.

The idea behind using a 2-stage furnace inside your home is that it gives you more control. There will be days when it’s so cold that you will need all the heat you can get. On some days though, the cold weather isn’t that bad so you can just use the lower setting.

What Are The Benefits Of A 2-Stage Furnace?

Old furnaces will eventually have to be replaced. Is it a wise move for you to replace your old unit with a 2-stage furnace?

To answer that question, let’s look at the supposed benefits presented by 2-stage furnaces and examine their true value.


Like we noted above, 2-stage furnaces are known for providing two levels of heating. Being able to adjust your heating to more precisely account for current conditions is regarded as a huge plus.

Here’s the thing though: The difference between the lower and higher stages may not amount to much. Studies have indicated that running the furnace at the lower setting may only result in a difference of about 10 degrees. There’s a good chance that the temperature difference will hardly be felt.

Energy Efficiency

Another often touted benefit of using a 2-stage furnace inside your home is energy efficiency. When it’s set to a lower setting, 2 stage furnaces consume less fuel than their single-stage counterparts.

It’s true that 2-stage furnaces do indeed use less fuel than the single-stage options. The fuel savings are small, but they can pile up.

That’s not the only element of the energy efficiency equation that matters though. You have to remember that new furnaces use electricity as well and this is where 2-stage furnaces struggle.

Ultimately, the difference in energy efficiency between single and 2-stage furnaces is not that significant. Feel free to factor it into the equation when deciding which model to buy, but it shouldn’t be the main consideration. Other elements of your ductwork and heating system will make a bigger difference in terms of energy efficiency.

Consistent Performance

2-stage furnaces are expected to offer more consistent performance. Depending on how you use your furnace, you can indeed take advantage of that benefit.

As long as you keep the 2-stage furnace operating at its lower setting, it will be able to consistently provide heat.

Once set to the higher setting, 2-stage furnaces become prone to fluctuating performance. That’s the same kind of issue that affects single-stage furnaces.

Quiet Operation

You’ll also read and hear a lot about how 2-stage furnaces are capable of operating with less noise. This is another advantage to using 2-stage furnaces that is very real. It does have a bit of a catch though.

2-stage furnaces can work quietly when they are operating at their lower setting. If you crank the heat up, they will be just as noisy as a single-stage furnace.

What Are The Disadvantages Of Using A 2-Stage Furnace?

Now that we’re done scrutinizing the supposed benefits of using a 2-stage furnace, let’s examine its clear drawbacks.

There are two, in particular, that stand out as clear reasons why you should reconsider making this kind of purchase.

Higher Cost

It will cost you significantly more to purchase a 2-stage furnace instead of a single-stage furnace. At the low end, 2 stage furnaces typically cost around $1500.

The more expensive models cost up to $2000. Don’t forget to account for installation costs as well. When it’s all said and done, you may have to spend $2500 to get a low end 2 stage furnace installed.

Compare that to how much single-stage furnaces cost and you’ll notice the big difference. Low-end single-stage furnaces cost around $1000. If you’re looking to splurge, a high-end single-stage furnace will cost you about $1500.

The working margin of cost between single and 2-stage furnaces is typically about $500. For new homeowners that already have a lot of expenses to worry about, those $500 can go a long way.

More Difficult And Expensive Repair

You’ll likely be using your furnace a lot and that will cause it to break down at some point. There’s a big gap between the ease and convenience of getting single and 2-stage furnaces repaired.

Repairing single-stage furnaces is pretty easy. Call a professional, have them diagnose what’s wrong, and have them apply repairs as needed. If some components such as the furnace’s draft inducer motor need to be replaced, finding a new part is no problem.

It’s not quite that simple if you have a 2-stage furnace. Replacement parts that fit 2-stage furnaces are usually harder to find. Because of that, repair time tends to be longer and the repair cost typically ends up higher.

Given how long furnaces are expected to work in homes, you can argue that single-stage furnaces are the wiser investments. The overall cost of maintaining them will be easier to shoulder and they’ll still deliver the kind of comfort you need.

Should You Consider Purchasing A 2-Stage Furnace?

Considering all the drawbacks to 2-stage furnaces we’ve highlighted already, is there any reason to install one in your home? Your answer to that question will depend on what kind of home you have and your tolerance for certain things.

If you’ve noticed that your home has hot and cold spots, a 2-stage furnace can be a smart purchase. That benefit is especially appealing if some of the cold spots pop up in rooms people use often.

2-stage furnaces are also worth having if noise is a big issue in your home. The quiet operation will present a welcome change.

Beyond those reasons, there’s no need to get a 2 stage furnace installed. Save your money and go for a single-stage furnace instead.

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Related Questions

What Does the AFUE Rating on a Furnace Mean?

While shopping for a new furnace, you may notice an AFUE rating on the appliance you’re looking at. So, what does that AFUE rating mean, and is it something you should pay attention to?The AFUE rating is shorthand for Annual Fuel Utilization Efficiency. As you might have already guessed, it’s a rating system that tells you how efficiently a particular furnace works. It is indeed something you should pay close attention to when browsing through your options.Not too long ago, you could find furnaces with AFUE ratings below 80 percent. Those are low-efficiency models and they’ve largely been phased out.These days, you can find furnaces with AFUE ratings in the 80 to 83 percent range. Those are considered the mid-efficiency options. Models with an AFUE rating of over 90 percent are considered high-efficiency furnaces.

Is the Heat Output Rating of a Furnace Important?

Yes, the heat output rating of the furnace you’re eyeing matters a great deal. Generally speaking, furnaces that have high heat output ratings work best in bigger homes.Don’t just purchase the furnace with the highest heat output rating though. You may just be wasting fuel if your furnace is too powerful for your home.

What Are Modulating Furnaces?

Modulating furnaces go several steps beyond 2 stage furnaces in terms of heating options. They present homeowners with different levels of heating, thus allowing for more precise temperature control. Their flames can be tweaked in different ways depending on what the homeowner prefers.

Upgraded Home Team
Upgraded Home Team

We are a team of passionate homeowners, home improvement pros, and DIY enthusiasts who enjoy sharing home improvement, housekeeping, decorating, and more with other homeowners! Whether you're looking for a step-by-step guide on fixing an appliance or the cost of installing a fence, we've here to help.

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