Ground Source Heat Pumps

Ground Source Heat Pumps....

Ground source heat pumps, also called geothermal heat pumps, are a great example of effective renewable energy technology which utilizes natural ground heat to keep your houses and offices warm in winters while cool in summers. This is a completely sustainable process that uses the natural heat from the ground and does not rely on fossil fuels to generate heat.

It is becoming quite popular among people, given its environmental and technological advantages. It reduces your carbon footprint while saving money on electricity bills too.

The working mechanism of ground source heat pumps

Ground Source Heat Pumps

This technology can be used at all times because the earth’s surface, beneath the ground, always has a constant temperature. It is warmer than the air above the ground in winters and cooler during summers.

So, the heat pumps use this natural mechanism by transferring the warmth of the ground to homes in winters and taking it back to the ground during summers. The ground is a source of heat during cold months and absorbs the inside house heat during hot months.

During winters, heat from the ground is transferred to the radiators and your house underfloor heating system via pipes running across your garden or porch. These pipes contain brine, which is an amalgamation of water and antifreeze. The loops or pipes can be buried in a trench outside the house or in a deep hole.

 The fluid absorbs the ground heat that is passed through a heat exchanger in the pump. The fluid becomes hot as the temperature rises, and then this heat is transferred to the inside of the house. It could also be used for warming water for domestic use.

Ground source pumps for heating water in homes

Ground source pumps for heating water in homes

Apart from heating the homes, the ground source heat pumps can also provide hot water when the system is being used. Many homes have desuperheaters that take excess heat from groundwater source pumps compressor to the home’s taps. However, desuperheaters cannot provide hot water when the ground source heat pump is not operational, mostly during the summer and autumn months.

Since geothermal pumps are becoming popular among consumers for meeting both house heating and water warming requirements, many manufacturers are giving ‘full demand ‘ systems with an inbuilt distinct heat exchanger to meet all the heating needs of the household. This system is also quite cost-effective and is efficient as people do not have to depend on separate equipment to heat their water during winters or even summers.

Where can you put a ground source heat pump system?

This system only requires some space outside your home to dig a trench or boreholes. There should be no trees as the roots can interfere with the pipes.

Ground pipes

The ground outside your house should be accessible to the digging equipment. It would be good if the space is not shady as shade would prevent the ground from absorbing heat in winters. The length of the pipes and the depth of the trenches would depend on the size of the house and the heat requirements. For digging the trenches and the system to function efficiently, there is a need for space 2.5 to 3 times more than the total house area.

Boreholes

If there is less space outside the house entrance, then you can go for a vertical borehole to trap ground heat. This is costlier compared to digging trenches and would also need a ground inspection.

If the house is big, then more than one borehole would be needed. The depth of the holes is 75 to 100 meters, but it changes depending on the weather conditions in the area you reside in.

Amount of space in the house

This system also takes up some indoor space for the installation of the heat pump unit, which has major heating components. It comprises a cylinder that is used for storing heated water. It is usually the size of a refrigerator, but you can choose a smaller one as well, depending on your water heating requirements.

Kinds of Ground Source heat pump systems

There are around four kinds of ground heating systems. They are horizontal, vertical, pond, or lake, which are closed-loop systems, while the fourth is the open-loop system. Variables like a region’s weather, soil type, land space can help you decide which system would be the best option for you.

Closed-Loop Systems

Closed-loop heating pumps worked by the circulation of antifreeze through pipe loops made of hard plastic and arranged like a closed loop. These tubes or loops are buried in the ground or in water. There is a heat exchanger that takes heat from the refrigerant to the antifreeze.

There is another system known as a direct exchange that does not have a heat exchanger but directly sends the refrigerant to tubes made of copper, buried inside the earth horizontally or vertically.

However, this system has limitations and cannot be installed everywhere. It needs a big compressor and works efficiently in moist soil, but it shouldn’t be installed in places having acidic soils as it uses copper tubes. Environmental laws at some places might discourage the use of the direct exchange system. 

Horizontal ground source heating pump

This system is best for homes, and especially nelly built ones where ample amount of space is available outside. This system requires a minimum of 4 feet deep trenches to be dug in which two pipes are used. Either the pipes are buried, one at six feet and the other at four, or they are placed along with each other five feet deep in a two-foot broad trench. The ‘Slinky method’ of looping the tubes is effective, for more pipe can fit in a smaller trench by using this. This is cost-effective and allows for horizontal installation of pipes in houses with limited space.

Horizontal ground source heating pum

Vertical system

Huge spaces such as buildings and offices use vertical ground source heating. Also, places having shallow soil are ideal for installing this system. In this system, holes measuring four inches are made at a distance of 20 feet away from each other and about 100 to 400 feet deep. Two pies connected, forming a U-shaped loop, are put into the hole. Then these vertical tubes are linked to the horizontal pipes in trenches and linked to the heat pumps in the buildings.

Pond Or lake system

This is the cheapest heating option but would be workable only if there is a water body nearby. A pipe is placed underground from the building to the water body and is coiled into circles and submerged at least 8 feet under the water bed to prevent it from freezing.

Open-Loop heating System

This system requires the usage of a well or surface water. This water is the heat exchange fluid that is passed through the GHP system. Once it has passed, it returns to the ground through the well or the surface. This system can work in places having clean water.

Hybrid heating Systems

As the name suggests, these systems use different types of geothermal sources or a combination of such sources along with a cooling tower. These systems are installed in places that need cooling rather than heating.

Advantages of ground source heat pumps

Some kinds of geothermal heat pumps have two compressors and more than two fans which make your home extra cosy while also saving up your electricity bills. Compared to air pumps, ground-source pumps do not make much noise, and they are more durable, do not require regular maintenance, and are not dependent on the outside air temperature.

There are also dual-source heat pumps that are a mixture of air-source and ground-source heat pumps. These pumps are highly energy efficient as well. The benefit of dual-source heat pumps is their cost. They are less expensive than geothermal heat pumps and work perfectly to meet all kinds of residential and commercial heating needs.

Cost of installing ground source heat pumps

Cost of installing ground source heat pumps

There are many types of ground-source heat pumps; hence the cost of installation, repair, and maintenance vary accordingly. However, it also depends on certain factors, such as whether you get a trench or a borehole or the kind of brand you opt for. It also depends on the model you go for and also its size. The house size and heat requirements also determine the costs apart from the fact that whether it is a new house or an old one.

It also depends on whether you are getting brand new equipment or just going for the repair of your radiators to improve the heat pump’s effectiveness. However, an average geothermal heat pump installation costs around £14,000-19,000.

Geothermal heat systems are more expensive than air-source systems. However, the extra costs would come back to you in a decade in the form of energy savings. Also, the ground source heating system worked fine for 24 years. People in the West are increasingly switching to geothermal heat systems. Figures show that 50,000 ground-source heat pumps are installed in the United States annually.