5 Frequently Asked Questions About Geothermal Heating
Geothermal heating (otherwise known as ground source heating) is an amazing source of renewable heat. But it can also be a little confusing.
To help simplify things, I’ve dove in to the 8 of the most frequently asked questions about geothermal heating.
Ready to learn more? Then let’s dive in!
1. How Does Geothermal Heating Work?
The first question people often have is about this technology actually works. For the best answer on this, check out our detailed guide to how geothermal heating works.
The concept is incredibly simple. Here’s the basics:
Summer is hot, and winter is cold… at surface level, that is.
As soon as you dig a little into the ground, you’ll find that the underground temperature never really changes. It’s an almost constant 55 degrees Fahrenheit (13C) once you’re 10 feet below the ground.
‘Geothermal Heating & Cooling’ sounds complex, but really it’s just accessing that consistent temperature in the ground.
A great example is a basement. Have you ever noticed that your basement is always cooler in summer, and warmer in winter, than the rest of your house? That’s a geothermal effect.
How is the heat/coolness transferred into your home? ‘Closed Loop’ systems like we use at Dandelion include a series of pipes filled with a water solution. This water is either warmed within the ground and used to generate warm air in the home. Or it’s warmed in the home, and used to disperse that warmth into the ground.
Note: the ground does get slowly hotter as you go deeper, because we approach the earth’s fiery core. The world’s deepest mine in South Africa – Mponeng Gold Mine – is 2.5 miles deep… with rock temperatures up to 151F!
2. What Are The Pros & Cons of Geothermal Heating?
Sometimes the easiest way to weigh something up is to consider it’s pros and cons. Here’s a basic rundown of the advantages and disadvantages of geothermal heating.
- Cheap to Run. Once installed, the system barely needs any power to operate.
- Cost Savings. Dandelion systems in particular can save homeowners up to 50% on their heating and cooling bills every month.
- Environmentally Friendly. One of the only heating systems which produces zero exhaust whatsoever, geothermal is great for the environment. In fact, it is the environment!
- No Big Units. Unlike a furnace or an air conditioner, there’s no big, loud, bulky unit that powers the whole thing. The system can easily be hidden within your floor/walls, and underground, of course.
- Safe. With no carbon monoxide or explosion risks, geothermal systems have much less risk attached to them.
- Add to Home Value. Offering such low heating and cooling bills can quickly add to your home’s value, if you’re looking to sell in the future.
- Financial Incentives. Incentives to help encourage people to buy geothermal systems are offered on federal, state, and utility levels. Check out the latest ones.
- Super Efficient AC. A geothermal system not only provides heating, it also provides cooling, and is typically 30-40% more efficient than a conventional central AC.
- Costly to Install. Traditionally geothermal has been costly to install because a homeowner needed to coordinate a drilling contractor, an evacuating contractor, and an indoor HVAC contractor separately to do the work. This resulted in quotes of over $50,000 for a typical home. Because of Dandelion’s business model and advances made to the drilling and heat pump technology Dandelion have driven the cost down to a typical cost of $18-25,000.
- Can Be Messy. A geothermal installation requires a team of installers to drill a 3-500 foot ground loop that’s 4-6 inches in diameter in your yard. To make this happen, the team needs to remove the dirt inside that hole, this can sometimes cause a mess, especially if there’s a high water table. That being said, Dandelion has figured out how to contain these messes, and return a homeowner’s yard to an acceptable form post installation.
- Could Take a While. A geothermal installation happens in 3 steps. First, the drilling is done and the vertical ground loops are installed. Second, the vertical ground loops are connected to the home. Third, the indoor HVAC equipment is replaced with a ground source heat pump. Each of these steps usually takes 1-2 days, plus anywhere from 3 days – 7 days between steps, which doesn’t sound so bad. However, different towns and municipalities have different permitting approval processes to get things underway. Some towns are able to return permits in a week or two, some take months. The goods news is, Dandelion has an entire permitting team that will push your project through from start to finish as quickly as possible.
3. Is Geothermal Heating Worth It?
Despite a high up-front cost, geothermal heating quickly pays for itself over the long term, especially if you heat with fuel oil or propane.
A typical homeowner in the northeast spends anywhere from $2-3,000 a year on heating fuel. With a geothermal system, that will be eliminated.
For many homeowners this results in savings of 50% a year with a geothermal heating system (your heating fuel bill is replaced with a much lower electricity bill). Homeowners who heat with fuel or propane typically see a payback of anywhere from 5-10 years depending on the size of their home and their fuel consumption.
This may feel like a long time – but you also need to consider:
- Your home’s value will increase. This can be hard to quantify, but an instant increase of $5-10,000 is easily achievable, when considering the lower monthly bills for the lifetime of the house.
- You’ll be warmer. Knowing that standard levels of heat are now super cheap, you can afford to stay warmer more often.
- You’ll have peace of mind. Nothing makes winter worse than the concern of how much the heating is costing. With a geothermal heating system you can stay warm without the worry.
4. Is Geothermal or Solar Heating Better?
This is a great question, but these two energy sources are quite different.
While a geothermal system provides heating and cooling, solar power provides electricity. In this way, these two make a perfect pairing. Geothermal for some of the most efficient heating on the planet, and solar to power the minimal electricity it needs.
If you’re comparing installing only one or the other – it mostly depends on your climate. Geothermal works best in cold regions, because the differential between the ground and underground temperatures are greatest. These regions are also more likely to have frequent cloud cover, diminishing the effectiveness of solar power.
However, if you’re enjoying life in a warm climate, you will likely be able to take much more advantage from solar power. More sunny days mean a better return on investment, and the efficiency of geothermal cooling isn’t quite as great an improvement as it is with heating.
5. How Much Land Do You Need for Geothermal Heat?
The space you need to install a geothermal system varies. Particularly, it depends on whether you’re using horizontal or vertical loop systems.
As their names suggest, horizontal loops stay closer to the ground, and run parallel back and forth with it.
Vertical loops dive deep into the ground, taking up much less space but needing a greater depth of installation.
Vertical loops need around 3-500 feet of depth. Don’t worry – the good news here is that these can be installed solely from the surface, and don’t require much space. Watch this Dandelion installation on This Old House to see an example.
Horizontal loops are less practical and can need up to 1200-1800 feet of underground space for a mid-sized home.
Geothermal Heating Systems may sound complex, but in reality they’re quite simple. They can save you thousands of dollars in bills each year, especially compared to traditional central heating or even using propane heaters in a garage.
I hope this quick guide helped dispel some of the questions you might have had around the topic.
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Thank you to Craig Anderson for writing this thoughtful piece on geothermal heating.
About: Previously a Geotechnical Engineer, Craig has taken his expertise online and can be found Running Appliance Analysts – a helpful home appliance and DIY blog.