How Big Is A Propane Furnace?

You've probably considered buying a propane furnace to heat your chilly nights now that we're only a few months away from winter. However, choosing the right size for your home might be one of the challenges you will encounter while looking for one. But, do not fret! We have already researched all that you need to know about which propane furnace fits best with your home’s measurements!

The size of a propane furnace is determined by the number of British Thermal Units (BTUs) it produces. A BTU is the heat required to convert one gallon of liquid water to one degree Fahrenheit. For you to know the size of the furnace, let us first identify your home’s ideal BTU. Just follow these steps: 

  1. Measure your home’s square footage.
  2. Identify your climate zone.
  3. Multiply the home square footage by BTU requirement (according to climate zone).
  4. Match the product of square footage multiplied by the BTU requirement according to the zone with the BTU needed for your home.

Phew! That sure was a lot to digest. We just always want to ensure our readers have all the necessary information rather than find it lacking. Now that you know the steps to finding the right propane furnace size according to your home, just keep scrolling as we now dive into the details of these steps!

A home high energy efficient furnace in a basement - How Big Is A Propane Furnace

Determining Furnace Size for Your Home

A home high energy efficient furnace in a basement

1. Measure Home's Square Footage

It is important that you know your home’s square footage. If you’re not certain, measure the length and width of your home. If it is a perfect rectangle, then just multiply these two numbers.

However, if your house has a complex layout, sketch your entire home with your corresponding rooms and measure each room by using the length x width formula. Then, add all the measurements together. The result would be your square footage.

2. Idnetify Climate Zone

To narrow it down further to exactly the right propane furnace for you, identify your climate zone. The climate map provided by the U.S. Energy Climate Administration gives the corresponding BTU of the zone you might belong in. 

3. Multiply Home Square Footage by BTU Requirement 

Now we head on to multiplying the square footage and the BTU requirement for your corresponding zone. The result reflects what would be the best BTU that would just be enough to complement the size of your home with the right amount of heat that you would want to flow around your home’s atmosphere.

4. Match Square Footage Product With BTU Requirement

Now that you already have your ideal BTU, you may now refer to the table below to know which size of furnace suits your home best.

Square Footage

(Home Square Footage Multiplied by Climate Zone BTU)


Furnace Size (in tons)

800 sq. ft. 36,000-40,000 3.0 tons furnace
1,000 sq. ft. 45,000-50,000 3.8 tons furnace
1,200 sq. ft 54,000-60,000 4.5 tons furnace
1,500 sq. ft 67,500-75,000 5.6 tons furnace
2,000 sq. ft. 90,000-100,000 7.5 tons furnace
2,500 sq. ft. 112,500-125,000 9.4 tons furnace

It is best if the product of your square footage and BTU requirement is within 10% of the “square footage” figures.  

More About Propane Furnaces

A home high energy efficient furnace in a basement

How Does a Propane Furance Work?

Unlike old heaters that rely on electricity, propane furnaces rely less on electricity and more on fuel for it to function. Propane furnaces work in a forced hot air system.

Forced hot air systems or forced air gas burns fuel to heat the air, and so this air travels through the ducts of the home and produces the heat inside each room, making sure the heat is equally divided among each room of the house.

Are New Propane Furnaces More Efficient?

Although the minimum efficiency rating of a propane furnace is 80%, some propane furnaces could have a standard efficiency that would reach 100%, with the costs varying as the standard efficiency rating increases.  

Energy-wise and cost-wise, propane furnaces are very efficient. Propane furnaces could save around 124 trillion British Thermal Units (BTU) annually. That is a lot of thermal energy saved! At the same time, propane furnaces could still continue to run in the middle of power interruptions. Because propane furnaces rely more on propane than electricity, they are definitely more cost-efficient.

How Much Does it Cost to Run a Propane Furnace?

A home high efficiency furnace, boiler water heater and humidifier.

Whilst Forbes argues that electric heating is much more cost-efficient than propane, the long-term cost for electric heating is higher than for propane furnaces. We have learned that the cost for propane furnaces varies as the standard efficiency rating increases.

Aside from this, the cost of running a propane furnace varies per region, with the cost changing from time to time. Because propane is a byproduct of oil and gas, its cost is directly affected by the changes in the price of the two.

From 2020 to 2021, the average national cost of propane per gallon was $2.22. However, the overall average cost to heat a home with a propane furnace on a national scale in the years 2020–2021 was $1,426. This amount is not inclusive of costs such as installation. On that note, the average installation cost of a propane furnace is around $3,000 to $6,000.

What Brand of Furnace is the Quietest?

The Lennox SLP98V claims to be the quietest brand of furnace on the market. With an efficiency rating of 98.7%, its unit price costs $2,365 and installation costs $3,712, making it the most costly of all of Lennox’s furnace models.

What is the Life Expectancy of a Propane Furnace?

The average lifespan of a propane furnace is about 15 to 20 years. But, if taken care of, a propane furnace could even live longer than 20 years. Proper sizing, installation, routine maintenance, and thermostat settings are factors to consider if you want your furnace to live longer. However, improper use could shorten the length of a propane furnace’s life.  

To Conclude

A person changing an air filter on a high efficiency furnace

As the winter season is fast approaching, we hope you are able to find the right furnace that will heat your home in a comfortable way. Choosing the right propane furnace for your home will surely do you wonders!

Check out this related post for even more great information on maintaining a home furnace: "What Should The Gas Pressure Be On A Propane Furnace?"


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