Geothermal Heat Pumps – What Are They and How Do They Work?
In a world where technology is constantly advancing and where fossil fuels are becoming scarce, an environmentally friendly heat source is necessary. A geothermal heat pump is a heat pump that uses the natural temperature gradient within an earth-filled well to transport heat from the earth into a living environment. Geothermal heat pumps are becoming more popular as an alternative heat source to fossil fuels since they are environmentally friendly.
What Is Geothermal Energy
Geothermal energy is a renewable energy source that produces energy from within the earth. Due to geological conditions such as low permeability between layers of earth and rocks, high temperatures rise through layers of rock, creating thermal gradients that lead to immense amounts of heat being trapped below the surface, where it is available for use.
A geothermal heat pump can use this heat to provide heating during cold winter months or cooling during hot summers. The energy generated from the earth’s core must be funneled through appropriate devices to produce heat at a cost comparable to that of fossil fuels and other forms of conventional electric power. That is where a geothermal heat pump comes in.
The Working Principle of a Geothermal Heat Pump
A geothermal heat pump is a passive heat transfer system that relies on the fact that the temperature beneath the earth’s surface remains relatively constant, at about 50 to 60 degrees Fahrenheit throughout the year. This means that the earth’s surface acts as the source of heat during winter and coolness during summer. The transfer of heat from the earth to a living environment occurs via a fluid that circulates through a pipe buried in the ground. The fluid is circulated using machine power.
What Are the 3 Components of a Geothermal Heat Pump?
A geothermal heat pump consists of the following three main components.
1. Earth Connection Subsystem
The earth connection subsystem is the part of the geothermal heat pump system that connects to the ground and transfers heat from below. It comprises a network of vertical and horizontal pipes that are placed beneath the ground. The pipes are connected to a well or borehole, which is then filled with gravel to provide better heat transfer.
2. Engine Subsystem
The engine subsystem consists of an engine-driven compressor, an expansion valve, and other components that allow for the proper operation of the system. Simply put, the engine subsystem is responsible for the components within the geothermal heat pump that generate mechanical energy.
3. Heat Distribution Subsystem
This subsystem includes conventional ductwork that helps to distribute heated or cooled air from the heat exchanger throughout the living environment.
Step-by-Step Operation of a Geothermal Heat Pump
The geothermal heat pump will go through a step-by-step operation. There are four steps in the process:
1. Refrigerant Circulates Through a Loop of Pipes
The refrigerant in a geothermal heat pump is circulated through a loop of pipes that are located beneath the ground. If the weather is cold, this coolant will be cooler than the earth’s temperature and will be heated up by the earth. If the weather is hot, the coolant will be warmer than the earth’s temperature and will be cooled by the earth.
2. Refrigerant Passes Through a Heat Exchanger
This system consists of a compressor, an expansion valve, and an optional metering device that controls the refrigerant flow. The expansion valve opens and closes to vary cooling or heating according to a thermostat’s commands. The heated or cooled refrigerant then goes through a heat exchanger, transferring heat to or from the air flowing through the home. The compressor and expansion valve also control the flow of refrigerant.
3. Cooled or Heated Air Is Pushed Through Ductwork
The heat exchanger pushes air through ductwork. This ductwork is routed according to a heating or cooling plan and can be found in many different rooms of the home. These rooms include living areas, bedrooms, and storage rooms.
4. Refrigerant Flows Back Underground
The now-used warm or cool refrigerant will be pumped back underground through a pipe. The refrigerant is circulated through a loop of pipes again, and the process continues until the desired temperature is reached.
How Much Heat Can Geothermal Systems Generate?
The amount of heat transferred from the earth’s core to the air above ground is a function of the depth of the geothermal well where it is being tapped. Larger pumps can transfer more heat because there is more surface area for heat flow through the pump.
When a geothermal system begins operation, it must be sized to handle heating needs throughout all seasons. Once the system has been sized and is operational, further expansion can only be achieved by replacing the entire system. In other words, geothermal systems do not scale like traditional systems.
Geothermal heat pumps don’t heat up as much as conventional boilers. For that reason, they can only produce as much as 35% of an average home’s heating needs. While conventional boilers can produce heat between 70-80 degrees Fahrenheit, geothermal systems can only produce heat between 35-50 degrees Fahrenheit. This should, however, not be a source of concern as that temperature is enough to provide comfort throughout cold winters.
Conventional boilers, or any other centralized systems, are not flexible enough to meet the significantly varying heating needs during winter and summer. Geothermal heat pumps are, however, able to do just that by simply adjusting their capacity.
It’s worth mentioning that due to their inability to produce as much heat as conventional boilers, geothermal systems have a smaller greenhouse footprint. Therefore, they are best suited to well-insulated and draught-proofed homes.
The Cost Factor
While it’s true that geothermal systems don’t come cheap, the savings that you will make in the long run by using a geothermal system will be significantly more than the initial cost.
Like any other energy source, geothermal systems are subject to the law of diminishing returns. This means that as each unit adds more and more heating or cooling, its contribution becomes less.
Geothermal Heat Pumps and Domestic Hot Water
In addition to conditioning the heating environment, these pumps can be used to provide hot water. Nowadays, many residential systems are equipped with desuperheaters. These devices transfer excess heat from the compressor of the geothermal heat pump to a home’s hot water tank.
The only disadvantage of this configuration is that desuperheaters can only provide hot water during winter and summer when the geothermal heat pump is operating. Manufacturers are now beginning to supply systems that utilize a separate heat exchanger to meet all household hot water needs during all seasons.
Reliable Geothermal Heat Pump Professionals
At Beyer Air Conditioning & Heating, we pride ourselves on the quality of our services. When it comes to geothermal systems, we can provide top-notch repairs and replacements. Customer satisfaction is at the heart of what we do, and for this reason, we always strive to give our customers products that meet the industry’s standards.
In addition to heat pump services, we provide repairs, maintenance, and installation for furnaces and air conditioners. We also offer air duct cleaning and repairs, air quality solutions, sheet metal fabrication, and VRF services. For more information, please contact Beyer Air Conditioning & Heating in San Antonio.