Outer Banks Heating & Cooling Blog

Geothermal Systems: What’s the Difference Between a Closed Loop and Open Loop System?

Brian McDonald - Tue, Aug 09, 2016 @ 12:48 PM

As homeowners and business owners, we’re always trying to find ways to save money on our energy bills and operating costs. One of the best ways to do so is to make sure you’ve got the most energy efficient heating and cooling system you possibly can. According to the EPA, there’s no contest here: geothermal systems are far and away “the most energy-efficient, environmentally clean and cost-effective space conditioning systems available today.”

As you start to do research on geothermal systems for your home or business, you will definitely start seeing the phrases “closed loop system” and “open loop system.” We’re here to help you understand the difference between the two!

Closed Loop Systems

A closed loop system is one that uses a continuous loop of pipes as the heat exchanger. These pipes are special buried plastic pipes that connect to your indoor heat pump. Together these form a sealed, underground loop through which the fluid being used to transfer the heat is circulated. The fluid is constantly recirculated, eliminating any water waste.

If your yard is large enough, the closed loops will be trenched horizontally adjacent to your home. If there is not enough space for the trenches to be horizontal, the system can instead be installed vertically, by using a drill rig. A closed loop system can also be installed to take advantage of a nearby pond or lake. In these instances, the pipe is submerged at the bottom of the pond.

The loops, when installed properly, will last over 50 years. The plastic they are made of is high-density polyethylene, which is inert to chemicals typically found in soil and is also flexible, meaning they are unlikely to sustain damage as the earth around them shifts.

Open Loop Systems

An open loop system is one that uses groundwater from a conventional well as a heat source in the winter and a heat sink in the summer. The groundwater is pumped through your heat pump, and the heat from the water is either extracted (in winter) or rejected (in summer). Then the water is disposed of appropriately - normally via what is called “open discharge,” where the water is released into a stream, river, lake, pond, ditch or drainage tile. Another option for disposing of the water is to create a return well back into the ground aquifer.

One of the potential issues that can arise when using an open loop system is poor water quality. Before an open loop system is installed, the water source must be tested for hardness, acidity and iron content. Skipping this important step could lead to major issues down the line. Mineral deposits can build up in the heat exchanger, impurities like iron can clog the return well, and excessive particles and organic matter can clog your system and make it inoperable.

Currently there is a 30% Federal Tax Credit available that will help offset the cost of installation for your primary residence. Note that the Tax Credits expire on December 31st this year.

If you’re interested in transitioning to a geothermal system and would like to learn more, the experts at Outer Banks Heating & Cooling can help! We’ve been involved with the installation and service of geothermal systems for over 20 years, and our factory-trained design, service and installation technicians will assure your complete satisfaction with your new system. Call us today at (800) 722-3094 or visit our website to get more information.

Brian McDonald

Brian McDonald

Brian McDonald has been in the HVAC industry since 1985. He holds NC HVAC Contractor's License #12643 and Refrigeration Contractor's License #3196. He also maintains NATE Certification #7330548 for installation and service of AC and heat pump systems as well as BPI Certification #5025287 for Building Analyst Professional, Building Envelope Professional and Heating Professional.

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