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Air source heat pump vs geothermal — Which is better?

Get the pros and cons of ground-source vs. air-to-air heat pumps in this guide.

Get the pros and cons of ground-source vs. air-to-air heat pumps in this guide.

If you’re weighing the difference between a geothermal heat pump vs air source heat pump—you’re already in the heat pump game. Good for you! 

Heat pumps are the Tesla of HVAC (and by far the most efficient heating and cooling system available today).

But there are distinct differences between the two technologies, and it can be confusing to parse through pages and pages of product reviews and articles on the Internet to figure out what’s right for you.

Good news: In this case, The Internet has not led you astray. 

Here, you’ll get all the information you need to make the best choice for your situation. That way, you can get your heat pump installed and move on with your (extremely comfy!) life.

Use the table of contents below to skip ahead if needed:

Let’s start by talking about the differences between the two heat pump technologies.

Geothermal vs air source — What’s the difference? 

Geothermal and air source heat pumps are very different beasts—but there’s one thing they share in common: They both work by transporting heat energy from one place to another. 

In the winter, heat pumps use refrigerant to transport heat energy from the outside of your home to the inside. 

And in the summer? They reverse the process and move heat from the inside of your home to the outside. So whichever kind of heat pump you choose, you’re going to get a complete, all-in-one heating and cooling solution for your home. Pretty cool!

Fall pump controlled by smart phone

One of the beauties of heat pump technology is its efficiency. Heat pumps only require a small amount of energy to move a large amount of heat, which is why they’re up to 3x as efficient as other HVAC technologies at heating and cooling your house (1).

That means that both geothermal and air source heat pumps will save you a ton of energy. (You can learn more about heat pump technologies here.)

Overall, they’re both great technologies! But they’re very different in how they operate.

How does a ground source heat pump work?

A geothermal heat pump, also called a ground source heat pump, uses the constant temperature of the earth (about 45 degrees Fahrenheit) to heat and cool your home (2). 

A typical geothermal system consists of an indoor heat pump unit that’s connected to a loop of underground pipes, called a ground loop (hence, the “geo” part of the name). 

The ground loop is filled with a water-based (“thermal”) solution, which transfers heat energy from the earth to the heat pump unit in winter—and vice versa in summer.

Geo + thermal = geothermal. Makes sense.

So what is an air source heat pump?

An air source heat pump uses outside air to control your home’s climate.

In winter, it pulls heat energy from the outdoor air (because, yes, there’s still heat energy in freezing cold air) and uses it to warm your home. In the summer, it does the opposite and pulls heat out of your home to cool it.

And as for aesthetics? An air source heat pump looks pretty close to a typical air conditioning system, with an outdoor compressor connected to an indoor unit (or units!) via piping. 

cold climate heat pump outdoor compressor unit on the side of a home

Some homeowners choose to route their air source heat pump through ductwork, while other homeowners prefer ductless mini-splits that require multiple units zoned for areas in your home.

If you’re fine with the look of a standard AC system, you’ll likely feel the same way about a heat pump system. (And if you go with a ductless mini split system and don’t care for the look, check out this article to learn how to disguise a mini-split heat pump system.)

Okay, those are the technologies. So which is best for you? And how on earth do you choose?

To find out, let’s take a look at the advantages and disadvantages of each.

The pros and cons of a geothermal heat pump

Let’s go over the advantages first.

Advantages of geothermal heat pumps

One advantage of a geothermal system is that it is somewhat more efficient than an air source heat pump, mostly because the temperature underground is more constant than the temperature of the air (which can vary a lot, especially in winter). 

That means that a geothermal system doesn’t have to work as hard to heat or cool your home—and that saves energy. It’ll cost less to run over time than a standard air source heat pump system, which will definitely reduce your energy waste.

To add to that advantage, a geothermal system is not dependent on outside air, it provides a higher efficiency than air source heat pumps in extremely cold weather. Air source heat pumps work well in very cold climates, too, and have been used (and loved) in Finland, Switzerland, and Minnesota. 

But geothermal units are in a league of their own. They could keep a house cozy warm at the South Pole. (A cool feature that’s necessary in some climates, but admittedly a bit of a party trick for the majority of American homes—as an air source heat pump should heat your home just fine in most of the U.S.)

Another advantage of geothermal systems? They have the potential to last longer than air source heat pumps (3).

While both types of systems are super durable, the underground elements of geothermal systems were originally designed to last longer because no one no one wanted to reinstall an underground loop every 15 years.

(Plus, geothermal units are less exposed to the elements; there are no mechanical components in a geothermal system that are located outside, which increases longevity.)

High-level recap of the pros of ground source heat pumps vs air source heat pumps:

  • They are slightly more efficient
  • They’re not dependent on outside air
  • They have the potential to last longer

All of that sounds great. So why are more homes not using geothermal heat pumps?

The simplest answer: There are significant disadvantages to using a geothermal system.

Disadvantages of geothermal heat pumps 

One big downside is that installation is hugely invasive—much more so than installation for an air source heat pump. Honestly? Installing a ground source heat pump is kind of a pain.

Geothermal systems require excavating and drilling in your yard, a lengthy project which can be disruptive to your grass, landscaping, and underground utilities.

In addition, because of the excavation involved, you’ll need more outdoor space for installation of a geothermal system than you would for an air source heat pump.

If your geothermal heat pump installation requires vertical pipes, they’ll require a depth between 100 and 400 feet. And if a homeowner is getting a horizontal installation, which is more popular with residential ground-source heat pumps, the installer will drill between four and six feet deep (4).

Your geothermal installer will do their absolute best to discover any issues on your property before your installation. But sometimes you don’t know there are physical drilling blockers on your property until after you’ve purchased the permits, rented the equipment, and started drilling.

The biggest drawback of geothermal systems, though, is probably their price tag. 

Because geothermal heat pumps have a major underground component, initial costs for a geothermal system can be significantly higher than for an air source system. A quality ground source heat pump in a large home could cost up to $45,000—or more (5).

And this number doesn’t account for permitting fees (if required), electric panel upgrades, monitoring of the equipment, or financing costs.

Repairs are rare, but when they’re needed, it could be a whole lot tougher depending on what breaks. (Turns out that burying things in the ground makes them harder to access and maintain—who knew?)

For a horizontal ground-source heat pump installation, the installer will drill between four and six feet deep.

Energy.gov

Ground source heat pumps vs air source heat pumps — Quick summary of the cons: 

  • Invasive installation
  • Higher price tag
  • More difficult to repair

That’s the roundup on geothermal heat pumps! 

And to be clear: We don’t want to deter you from using a geothermal heat pump if it’s right for you. They’re incredible HVAC systems that last a long time—and if you’re willing to make the larger initial investment and have the outdoor space for one, you’ll love the dependability.

Before you make that decision, though, let’s try the air source heat pump on for fit.

The pros and cons of an air source heat pump

Okay, let’s dig into the advantages and disadvantages of air source heat pumps (sometimes called air to air heat pumps or mini split heat pumps).

Advantages of air source heat pumps

To be very blunt, the biggest advantage—and you probably saw this coming—is that air source heat pumps are far less invasive to install, which makes them less expensive than their geothermal cousins. 

Air source heat pumps provide most of the advantages of geothermal systems, but for less money and effort because you won’t have to excavate or bury anything in your yard. This is a major benefit. It’s why most homeowners opt for air source heat pumps.

It’s not the only advantage, though. Air source heat pumps are far more flexible in terms of installation location. 

Unlike geothermal systems, which need an outdoor space for the underground component, air source heat pumps can be installed just about anywhere. That means they’re a great option if you live in a city or have a small yard. 

(They’re especially great for heating and cooling a large, old house, since they don’t require ductwork.)

Air source heat pumps are also easier to maintain than geothermal systems. Because they don’t require an underground component, maintenance and repairs are simpler and less expensive.

Finally, a huge pro of air source heat pumps is that you might be able to get one for no upfront cost! (See if your home qualifies here.)

A quick look at the pros of air source vs geothermal heat pumps:

  • Less invasive to install
  • Customizable, flexible installation options
  • Easier to maintain
  • You may be able to get one at no upfront cost
two HVAC professionals install a heat pump outdoor compressor unit

Disadvantages of air source heat pumps

So what about the disadvantages?

The first one is lifespan. Both technologies are durable, but air source heat pumps last about 15-25 years, depending on your local climate (6)—not quite as long as the ground source option.

The other potential disadvantage of an air source heat pump is that it’s completely dependent on heat energy from the outside air during the winter. While that normally works fine (even very cold climates), air source heat pumps can struggle in extremely cold climates. 

That means if you live somewhere where temperatures routinely dip (and stay) below -13 degrees Fahrenheit, you may need to install some form of supplemental heating for very cold days. 

(Curious if this applies to you? Read more here: What temperature does a heat pump stop working?)

Cons of air source heat pumps: Quick list

  • 15-25 year average lifespan, depending on your local climate and how well your house is insulated and air sealed
  • Extremely cold climates (regularly well under -13 degrees Fahrenheit) may need backup heat

Air source heat pump vs geothermal — What should I choose?

All of that leads us to the big questions: 

  • Which is the right heat pump for your situation? 
  • Should you go with an air source mini-split heat pump system or a centrally ducted system?
  • Are ground source heat pumps worth it?

Here are a few guidelines that might help you choose the best heat pump for your situation.

A geothermal heat pump might be better for you if one or more of the following apply…

  • You want the absolute max energy-efficiency and are prepared to make a larger initial investment
  • You live in an extremely cold climate and want a heat pump system that can handle extremely cold temperatures (consistently below -13 degrees)
  • You have enough outdoor space to bury the necessary underground component
  • You’re looking for an HVAC system with the absolute longest lifespan—regardless of cost

An air source heat pump might be better for you if one or more apply…

  • You want all the comfort, efficiency, and health benefits of a heat pump with a smaller price tag
  • You don’t have the outdoor space necessary for a geothermal system (or you don’t want your yard torn up!)
  • You’d like all all the advantages of a heat pump system with minimum hassle
  • You don’t live in a climate that regularly experiences temps consistently below -13 degrees—and have no need for a heat pump with South Pole heating capabilities
  • You’d prefer to get a heat pump installed for no upfront cost

And since there’s a lot to consider there, here’s where we’ll throw in our opinion:

First, know that we’re huge fans of both kinds of heat pumps. Either kind of system is going to make you (and the people and pets who live with you) extremely happy. 

And no matter what type of heat pump you install, make sure your home is well-insulated and air sealed to make the most of your investment and extend your heat pump’s lifespan.

But we’ve been in the HVAC business for a long time, and we’ve found that—for most homeowners—an air source heat pump is the best choice. 

But if you’d prefer to talk it through with an expert, we’re happy to help dig into the details. (At Sealed, we love to talk heat pumps!) Talk to us at 917-905-3788—a phone call is free.

While geothermal units are great, they’re very expensive and a huge hassle to install. That means they’re often better used in big corporate situations (where they have big, corporate budgets!) or for homeowners who have a lot of control over their property (or have a large yard or lots of land).

And the truth is that air source heat pumps can handle just about anything a geothermal system can—with a lot more flexibility and for much less money and effort.

Even better, of course, is that you could get one for NO upfront cost.

Are you wondering how that works? Well, here’s the rundown.

Get a heat pump installed for ZERO upfront cost

Since you’ve been researching heat pumps, you know that they’re the best HVAC tech out there right now. 

The biggest disadvantage is the upfront financial hit. Quite frankly: That’s why heat pumps aren’t in more homes right now.

The good news, though, is that if your house qualifies, you can get an air source heat pump installed for ZERO initial cost.

Here’s how the program works: If you qualify for Sealed, you’ll get a complete, custom, and stress-free home energy makeover—we’ll put in the initial labor, expertise, and funds. 

Your home makeover could include an air source heat pump, if that’s what’s best for you. But it’ll likely include air sealing or better attic insulation, if those will make your home more efficient and comfortable. 

It all depends on your house. (You’ll get the comfort and efficiency upgrades you need—and nothing you don’t.)

We’ll also help you understand all the home energy rebates and utility incentives that could apply to your project.

And the money?

You’ll pay us back little by little, at a rate based on the energy you save because of our work. If we don’t help you save energy, then we don’t make money. We stand by our work over the long term, too.

See if your house qualifies. It only takes two minutes.

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October 14, 2022