Eanes Heating & Air


What Size Furnace Do I Need for My House?

What Size Furnace Do I Need for My House?

The last thing you should worry about during the winter is if your furnace will heat your home efficiently.Your furnace can only do its job when its size matches your home, so choosing the perfect furnace size is crucial. If your furnace is too big or too small, you’ll run into issues costing you money, time, and comfort.

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Why Furnace Size Is So Important

You’re probably wondering if you can get away with purchasing a smaller furnace to save money, or if buying an extra-large furnace for your area will give you better overall heating. However, there are a few important things to consider.

If you get a furnace that’s too large:

  • It will be less efficient.
  • It will heat your home unevenly.
  • You will have to perform more maintenance.
  • You’ll have to replace it sooner.

If you get a furnace that’s too small:

  • It will run all day, raising your energy bills.
  • It’s more likely to need frequent repairs.
  • It won’t keep up with your heating needs.
  • Its increased workload will cut its life short.

You don’t want to guess when it comes to furnace size. Let our local HVAC technicians help you get the right size furnace to heat your home efficiently!

Related: Electric Furnace vs. Gas Furnace

Calculate Your Home’s Square Footage

The first step for determining what size furnace you need is understanding your home’s square footage. The formula is simple: your square footage is your home’s length multiplied by its width.

However, most homes aren’t perfect shapes—you may need to measure each room separately and add their sq. footage together to calculate the overall square footage.

Luckily, you likely have documents listing your home’s square footage. You can find this number on your property tax assessment or mortgage documents from when you bought your home.

Finally, if you’re unsure of your home’s square footage and don’t want to deal with measuring each room, our heating and air repair pros can help you determine what size furnace you need.

What Is BTU for Furnaces?

British Thermal Units, or BTUs, are how we measure the energy output of appliances like furnaces. They measure how much energy the appliance takes to heat a pound of water by one degree.

The BTU rating of your furnace represents how quickly and effectively it will heat your home. Larger furnaces will output more BTUs per hour and generate more heat for larger spaces than smaller ones with a lower BTU per hour output.

The BTU rating you need isn’t set in stone. The square footage of your home will give you a pretty good idea of the size of furnace you should look for; however, other things impact how large of a furnace you need, like:

  • Your climate
  • The number of exterior walls your home has
  • The number of doors and windows in your home
  • The condition of your ductwork
  • The style of your home
  • The type of insulation you have
  • How efficient the furnace is

You can use this BTU calculator tool to calculate your home’s BTU needs.

Next, let’s discuss the size of the furnace you’ll need depending on your home’s square footage. Remember that the following recommendations are estimates—the size you need will vary based on the factors mentioned above.

Related: What Do the Different Furnace Flame Colors Mean?

What Size Furnace Do I Need for a 2,500 Square-Foot Home?

If you have a home measuring around 2,500 square feet, you’ll need a furnace with a high BTU output to heat enough air to keep it at a comfortable temperature.

2,500 square-foot homes will typically need a furnace rated anywhere between 70,000 and 140,000 BTUS or higher, depending on your climate and the qualities of your home.

…for a 2,000 Square Foot Home?

If you have a 2,000 sq. ft. home, that’s still a large area you need to heat. This size of home still needs a large furnace.

If you want to evenly heat a 2,000 sq. ft. home, you’ll need to look for furnaces rated between 60,000 and 125,000 BTUs, depending on the factors we discussed earlier.

…for a 1,500 Square-Foot Home?

If your home is closer to 1,500 square feet, you won’t need quite as large of a furnace to keep it heated comfortably. However, size does matter when it comes to furnaces!

In an ideal climate with a quality-built home, you could get away with a BTU rating as low as 45,000, but you could also need one up to or over 100,000 BTUs if conditions are less-than-ideal.

…for a 1,200 Square Foot Home?

The best part about owning a smaller home is that you don’t need a large, expensive furnace to heat it! 1,200-square-foot homes are on the smaller side, but keeping them warm is easy.

Depending on where you live, the age of your home, etc., you will likely need to invest in a furnace that’s rated anywhere between 35,000 and 70,000 BTUs for a 1,200-square-foot home.

how to determine furnace size

Call Eanes Furnace Experts for Furnace Installation

Is it time to replace your furnace? The following are common signs that you need to start thinking about having a new furnace installed:

  • Uneven heating
  • Increased energy bills
  • Visible damage
  • Unusual smells
  • Repair costs creeping up
  • Takes ages to heat your home
  • It’s 10+ years old
  • Excessive noise
  • Frequent issues
  • Doesn’t meet AFUE standards

Replacing your furnace doesn’t have to be stressful! Book an appointment with our heating pros, and we can help you find the right size furnace at the right price and get it installed quickly to keep you and your family comfortable, no matter the weather.