Furnace Buying Guide: Everything You Need to Know to Find the Best One for Your Home

Whether you're looking for electric, gas or another furnace option, we've got you covered with the ultimate furnace buying guide.

Lauren Ward Contributor
Lauren is a contributor for CNET.
Lauren Ward
7 min read
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Cooler temperatures aren't here yet, but it's worth researching ahead of time if you're in need of a furnace upgrade. Fortunately, the market these days is flooded with options. To pick the right one for your home and needs, you need to know what you're looking at. Whether you're just researching or looking to make a purchase, we can help you get acquainted with the different types of furnaces, the installation processes and the heating experience through our guide below. 

The four types of furnaces

There are four different types of furnace currently on the market:

  • Electric
  • Natural gas
  • Oil
  • Propane

Each type of furnace heats the air a little differently and has a different operating cost.

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Electric furnaces

Electric furnaces are often the cheapest of the four to purchase and are easier to install and maintain. However, because they run solely on electricity, they can be quite expensive to operate. 

Think of an electric furnace as you would a hair dryer or toaster. The furnace pulls cold air into an exchanger where it is then heated over electric heating elements. Once heated, the warm air is pushed into your home via ductwork. 

Even though an electric furnace costs more to operate, the plus side is that it doesn't produce any carbon monoxide -- making it safer for the environment and your family's health. 

Natural gas furnaces

If you live near a natural gas line, a natural gas furnace can be more affordable to operate than an electric furnace -- especially if there is already a natural gas line running to your home. 

A natural gas furnace works by igniting natural gas inside of your furnace's burner. The flames heat up a metal heat exchanger, which in turns heats incoming cold air received from your home's ductwork. The warm air is then pushed into your home by a blower via its ductwork. 

Natural gas furnaces require a flue for the exhaust to exit your home. The flue pipe will need to be inspected at least once a year to prevent poisonous gasses from entering your home.

A gas furnace costs more to purchase than an electric furnace, but because it uses natural gas as opposed to electricity, it is less expensive to operate. It is also more powerful than an electric furnace because it is able to heat the air within the heat exchange chamber more quickly. 

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Oil furnaces

Oil furnaces work much the same way as a natural gas furnace. Once activated, the furnace draws oil from the tank into a burning chamber. Instead of being directly lit, however, it is first converted into a mist and then sprayed onto a burner. Once ignited, air is pulled into a chamber near the burner where it is heated and sent back into the home through the ductwork.

Oil burns at a hotter temperature than natural gas, which means it heats up homes faster. However, keep in mind that oil furnaces require an oil tank, which are often buried near homes. 

Propane furnaces

Propane furnaces also operate much the same way as a natural gas furnace, except they do not require a flue. It's possible, instead, to simply install a direct vent beside it on an exterior wall. This eliminates the need to have a flue regularly inspected and cleaned. 

However, even though it is similar to natural gas, propane furnaces are more efficient. The result is that you don't have to burn as much propane to get the same amount of warmth you'd get with a natural gas furnace. 

Single stage furnaces to modulating heat furnaces: Which is best?

In addition to choosing between different fuel sources, you also need to consider how many stages you want your furnace to have. There are currently three options on the market.

  • Single stage heat: Many older furnaces use what is called a single state heat process. With this type of furnace, there is only one size flame and it is either on or off. In relation to the thermostat, it is not very precise, meaning that it is usually within a couple of degrees. Because it only has one flame setting, it will repeatedly turn on and off throughout the day as temperatures fluctuate. 
  • Multistage heat: This type has two sizes of flames it can utilize. A smaller one for mild weather and a larger one for colder weather. Because it has two flame options, it is more precise than a single stage heat furnace. 
  • Modulating heat: This is the most accurate furnace on the market because it is able to control the size of the flame to meet the temperature established at the thermostat. It's a steady heating source that keeps your home's temperature right where you want it.

A single stage thermostat is more affordable, while a modulating furnace is the most expensive. To choose, consider your budget and needs. Smaller, single-story homes don't require as much heating power as larger, multistory homes. If your home is somewhere in the middle, then a multistage heat furnace may be the perfect fit for you. 

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What is an AFUE rating?

AFUE stands for annualized fuel utilization efficiency. An AFUE rating reflects how much heat is produced for every dollar spent. The higher AFUE rating a furnace has, the lower the amount the homeowner should spend on fuel. 

Ideally, you want a furnace with an AFUE rating in the '90s because these are the most fuel efficient furnaces. However, just be aware that furnaces with this high of an AFUE rating are usually some of the most expensive.

How much does a new furnace cost? 

A midrange, new furnace costs between $1,500-$6,000 (for example, a Rheem furnace, which has an 80% AFUE rating, costs $1,488 plus installation). Opt for a high-end model with a higher AFUE rating and the cost may jump up to $10,000. 

Next you need to consider the cost of installation, which should be around $2,000 without any discounts. 

Because it is such a large investment, consider the cost of fuel and operating costs, too, before you decide. This is especially important if you plan on financing the purchase and will have monthly payments (but you could always offset your energy costs with some new solar panels).

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Supporting structures and hidden costs: Chimneys, ductwork, vents and whole house humidifiers


Your furnace needs ductwork to transfer heat into your home. If you live in a newer home, your home's ductwork is likely already well taken care of. However, you will still want to have a licensed HVAC technician come to your home and test your home's ductwork system. It may or may not be able to handle a furnace with greater blowing power. 

If you have been having issues with an older furnace, it's possible your ductwork may be to blame. The technician will be able to tell you if the ductwork was properly installed, or if there are any leaks or blockages. If there are any damages to your ductwork, it's unlikely you will need to get the entire system replaced. Instead, you may be able to get by with just replacing the damaged portions. 


Chimneys aren't just for fireplaces. They can also dispel gasses from a hot water heater or furnace. If you purchase a high efficiency furnace, it's possible you won't even need a chimney at all. However, if not, you'll want to get your chimney inspected before getting your new furnace installed. Thereafter, you will need to get it cleaned once a year. 


We're not referring to the air registers in each of your rooms that you can open or close. Instead, we're referring to the vents that direct flue gases to the outside of your home. If you change the type of furnace you use, you may need to replace your vents. Propane, oil and natural gas all burn a little differently, so the material used in your outdoor vents may not be strong enough to handle new temperatures. 


Furnaces dry out the air in a house, which isn't a good thing during the cold and flu season. Sinus infections can result from breathing too much dry air. To combat this, many homeowners opt to install furnace humidifiers. The cost of a furnace humidifier varies a lot depending on which make and model you choose. You can spend as little as $200 to as much as $1,600. Putting a single humidifier in each room is also a valid option. 

Which one is right for you?

The best thing you can do for yourself is to have a licensed HVAC technician come out to your home. Once there, they can address your concerns about your old heating system, as well as give you their professional opinion about the best type of furnace for your home. While there, you may also want to speak to them about your cooling system, too. Window units are often the best choice, but sometimes there is room for an upgrade.

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