Geothermal Heat Pumps: Exploring The Future of Energy Efficiency

Posted on: August 28, 2015

If you’re ready to consider an HVAC upgrade for your Raleigh home, a geothermal heat pump may offer the perfect solution. Though this technology isn’t as widely known as other options, it offers an eco-friendly choice for maintaining your home comfort. Cut down on energy use and update your home with cutting-edge technology by adding a geothermal heat pump.

How Geothermal Heat Pumps Work

While air temperatures can fluctuate dramatically from one season to the next, the temperature underground remains relatively unchanged. The ground absorbs almost half of the solar energy that our planet receives, keeping that warmth below the surface. Traditional heating and cooling systems use outdoor air to change the temperature inside the home, but this is far from efficient. In the coolest and warmest months, these systems have to work hard to change the temperature of air brought in from outside. Meanwhile, ground temperatures maintain constant levels, offering a high-efficiency alternative.

Geothermal heat pumps circulate liquid through an underground loop. Systems use either an antifreeze solution or water. A heat exchanger transfers heat between the water or antifreeze solution in the loop and refrigerant in the heat pump. As it moves through this loop, it exchanges heat between your home and the earth. In summer months the system absorbs heat from your home and sends it into the underground loop where temperatures are cooler. The liquid cools as it moves through the pipes and returns to your home to provide cool air. In winter, the process reverses. The geothermal heat pump sends cool liquid underground where it warms up, taking heat from the earth.

Types of Geothermal Heat Pumps

There are three primary types of geothermal heat pump loops. The options that are available for your home will vary depending on the size of your lot, home, and budget. The most common options are:

  • Horizontal Closed-Loop System: Pipes are buried in long trenches at least four feet deep. Most systems include two pipes for each trench. These are either positioned with one at four feet and another at six feet, or with two pipes together at five feet within a two-foot-wide trench.
  • Vertical Closed-Loop System: Pipes are inserted into deep vertical holes between 100 and 400 feet deep. Holes are drilled about 20 feet apart with two pipes looping down and back up from each hole.
  • Pond or Lake Closed-Loop System: Pipes are run underground from the building to a nearby body of water. Looping pipes are placed at least eight feet under the water.

Open-loop systems are another less common option. This type of system is only possible where there is an ample supply of fresh water and a nearby well. This type of system uses well water in place of an antifreeze solution. The water circulates through the system and then returns to the well.

Understanding Dual-Source Pumps

A dual-source heat pump combines technology for both a geothermal heat pump and an air-source heat pump. These units are a smart choice if you want extensive heating and cooling beyond what a geothermal heat pump can offer. Extreme temperatures limit the geothermal heat pump’s capacity. A dual-source pump is more efficient than an air-source pump, but less efficient than a geothermal heat pump used alone.

Energy Savings with Geothermal Heat Pumps

Geothermal heat pumps use just one unit of electricity to move as many as five units of heating or cooling. This means they use 25 to 50 percent less electricity than a conventional heating or cooling system. While air-source heat pumps have efficiency levels of 175 to 250 percent, a geothermal heat pump offers efficiency of 300 to 600 percent in extreme temperatures. A geothermal heat pump is between 3.5 and 5 times more efficient than a fossil fuel furnace.

If you’re looking to reduce greenhouse emissions, a geothermal heat pump will cut down on your electricity use and associated emissions by 44 percent when compared with an air-source heat pump, and a whopping 72 percent compared to standard air-conditioning equipment.

Cost Benefits for a New Geothermal Heat Pump

A geothermal heating and cooling system can reduce your energy bills by 40 to 60 percent. Although installation costs are higher for a geothermal heat pump than for a traditional HVAC system, most homeowners will recoup the difference within 5 to 10 years because of the ongoing savings. A geothermal heat pump has a lifespan of about 25 years, so you will have ample time to reap the rewards of this system. Meanwhile, a traditional air conditioner lasts between 10 and 15 years, a furnace lasts 15 to 20 years, and an air-source heat pump will survive about 16 years.

A 30 percent tax credit will further reduce the cost of your geothermal heat pump installation. It’s also important to note that you only need to replace the heat exchange equipment. The underground loops can last for generations, so the installation cost of this equipment is a well-spent investment.

Geothermal Heat Pump Myths Debunked

There are several common myths that often prevent people from investing in geothermal heat pumps. Here’s the truth behind some typical misconceptions.

  • Geothermal heat pumps require a lot of real estate: Vertical heat pumps require only minimal space and are easily added to an existing home or office building.
  • These systems are very loud: Geothermal heat pumps are actually very quiet. They do not have any of the outdoor equipment that a traditional HVAC system includes.
  • Geothermal heat pumps only heat the home: Geothermal heat pumps, like all heat pumps, can both heat and cool the home. Their name leads to a common misconception that this equipment is solely used for heating purposes, while it is actually efficient for maintaining home comfort in any season.
  • Geothermal heat pumps consume water: A geothermal heat pump will not add to your water bill. Closed-loop systems circulate an antifreeze solution. Open-loop systems that do use water will return it to the same aquifer after use. Traditional systems use more water because it evaporates from the towers of their cooling units.

Added Features of Geothermal Heat Pumps

Geothermal heat pumps can do more than heat and cool your home. You can also opt for an installation that offers supplemental hot water generation. This will further lower your energy costs while giving you an eco-friendly home. Other features available with geothermal heat pumps such as the PerformanceTM series GT model include:

  • Two-stage compressor
  • Variable-speed blower
  • Dehumidification control
  • Microprocessor control for precise temperature adjustments
  • MERV (minimum efficiency reporting value) 8 to 13 filtration

How to Choose a Heat Pump

If you’re ready to upgrade your HVAC system, a geothermal heat pump is a compelling choice for energy and cost savings. To get the optimum efficiency out of your unit, check the Energy Efficiency Ratio (EER). This indicates how much heat is removed in Btu each hour compared to the wattage used to run the unit. Energy Star labels can also help you identify the most efficient units.

The amount of land available for your unit will determine which type of loops are best for your home. If you have limited land, a vertical loop system is typically best. If you have the room for long trenches, you don’t have to dig nearly as deep for a horizontal closed-loop system.

If you’re considering an open-loop system, make sure your installer inspects ground water thoroughly. Open loop systems can make smart, eco-friendly use of ground water, but you must consider how much water is available and the quality of your water source. Aquifer depletion and groundwater contamination pose potential threats to systems that are installed without proper inspections.

A geothermal heat pump will increase the value of your home, setting it up for high-efficiency heating and cooling for generations to come. The long-lasting underground loops require a one-time installation that you will benefit from long into the future. This is a truly innovative way to redefine heating and cooling for your home. Learn more about geothermal heat pump technology by calling Air Experts at 919-881-2132.

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