Find out how geothermal heat pumps work and if they are a cost effective solution for you.
In comparison to conventional heating systems, ground source heat pumps are an eco-friendly and cost-effective heating system with which you can save up to 50% on your heating bills. The initial price of this type of heat pump systems can be a bit off-putting, and the cost will vary greatly from property to property.
- 1 How Suitable Are GSHPs for Your House?
- 2 Geothermal Heat Pump: The Cost
- 3 GSHP: Savings
- 4 Efficiency
- 5 GSHPs: The Pros and Cons
- 6 The Installation Process of Geothermal Heat Pumps
What’s In This Guide?
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There are multiple advantages to GSHPs. For example:
The temperature under the ground remains within a pretty stable range throughout the year. In the UK, the ground temperature a few meters below the surface of the Earth varies by about 3 degrees Celsius throughout the year. And it’s this stable heat source that geo thermal heat pumps draw from.
How Suitable Are GSHPs for Your House?
First of all, a thorough assessment of your dwelling in terms of hot water and space heating consumption is necessary to choose the right design for a ground source heat pump. It will involve a careful review of the energy efficiency of your house which can be carried out with the help of authorised technical advisors from SEAI. By doing so, you will be able to find a heat pump system of the right size which will help reduce your use of energy, heat loss, and improve the energy efficiency of your home.
Geothermal Heat Pump Types
Geothermal heat pumps come in two different types: an open-loop and closed-loop system. The open-loop system uses underground water to extract the heat and transfer it through a heat pump. The closed-loop system uses the ground to extract the heat and transfers it through the piping connected to the indoor heat pump system. The closed-loop systems can also be of several different types.
At an approximate depth of one to two metres, the ground source heating system is installed in horizontal channels. It is suitable for properties that have more available land, such as suburbs or rural areas. The size of the required territory for the horizontal system installation is determined by several factors, such as heating and cooling capacity of your house, depth at which the heat pump will be installed, type of soil, the climate and heat pump efficiency. For the average house of 150 square metres, the required space should be between 300 and 700 square metres.
Vertical geothermal pumps are more suitable for suburban homes with the limited space. For this reason, they can be more expensive than the horizontal system. A vertical hole is drilled at least 6 metres deep in the ground, and the entire piping of the heat pumps system will go 50 to 150 metres deep, depending on the amount of heat required for your house and the soil structure.
Pond Closed Loop System
Another type of heat pump system is a closed pond loop system. However, it is not as popular as horizontal or vertical systems. It can be more complicated because it requires close access to a water source. In this case, an open loop system is more appropriate. However, a closed pond loop is beneficial if the quality of water is poor and it isn’t suitable for an open loop system.
Geothermal Heat Pump: The Cost
In comparison to air source heat pumps and conventional heaters, ground source heat pumps are more expensive, but this initial cost is paid off by the savings on future energy use. The average installation cost of geothermal heat pumps varies between £15,000 and £23,000. The operational costs will also vary depending on the size of your house and the degree of insulation.
Another factor that can influence the price of the ground source heat pump is whether or not new radiators or underfloor heating systems are also required.
Vertical vs. Horizontal System Costs
The installation price of a geothermal heat pump will also greatly depend on which type of a system you decide to install. The difference in price between vertical and horizontal heat pump systems is quite significant. The horizontal system is more affordable, but it requires a large area for the system installation (half an acre minimum).
The numbers provided in the table above are ball park figures to give you an idea. The actual price will depend on every specific project.
In the table below we have provided approximate numbers which represent the amount of money that you can save on energy bills and the reduction of carbon dioxide use with a ground source heat pump. As you can understand, the savings you will see depend on your a great many factors. All the systems listed in the table are non-condensing which are most likely to be replaced in the majority of households.
Geothermal heat pumps use the constant temperature of the ground to save energy and increase the seasonal efficiency of heating. They operate using solar energy heating up the underground water which provides a constant temperature of the ground.
GSHPs use electricity to generate the heat. For every kilowatt of consumed electricity, they generate 3 to 4 kW of heat which makes the cost-effectiveness ratio 300% to 400%.
COP and SCOP
COP is a coefficient of performance which is used to measure the efficiency of a ground source heat pump. COP of GSHPs is calculated by dividing the heat output by the electric energy input.
For example, a ground source heat pump that can generate 4 kW of heat per one kilowatt of electricity has a COP of 4. SCOP represents the seasonal coefficient of performance, and it can be more accurate when you need to calculate the pump’s efficiency during a particular season.
GSHPs: The Pros and Cons
Although the installation of ground source heat pumps require some land available, it does not mean that you will need several acres of land. Even an average garden can serve as a source for a heat pump.
Geothermal Heat Pumps: The Advantages
Ground source heat pumps are one of the most energy-efficient heating systems.
- They don’t require high maintenance and are affordable to run.
- Compared to boilers and air source heat pumps they produce less noise.
- The influence on the environment is quite low because ground source heat pumps produce a low level of carbon. With the use of renewable energy source to power the heat pump, there are no carbon emissions.
- Compared to the air source heat pumps, the indoor components of the ground source heat pumps last longer, up to 25 years.
- The initial cost can be high. Unlike air source heat pumps, ground source heat pumps require the installation of a ground heat exchanger. Therefore, it increases the costs.
- The amount of energy produced by a vertical ground heat pump will depend on the type of bedrock.
- For the horizontal ground heat pump installation, a large area is required because the pipes should be spread out horizontally.
A Renewable Energy Source
As mentioned before, geothermal heat pumps use electricity to produce the heat. If you want to be even more environmentally-friendly and reduce carbon emissions, you can combine your heat pump system with a renewable energy source. For example, by integrating solar panels, you can have a system completely carbon neutral.
The Installation Process of Geothermal Heat Pumps
If you decided to have a ground source heat pump installed on your property, you would get either a vertical or horizontal loop system. The most suitable system for your home will be offered based on the size of your house and land, and the building requirements. First of all, the ground should be adapted for the installation of the system by digging up the loop fields.
For the installation of a vertical ground source system, the wells should be drilled deep into the ground in which the loop will be placed. Next, the installation of the heat exchanger which will hold the heat from the ground is required.
The installation of a horizontal system does not require digging deep into the ground. Instead, a large piece of land for the loops installation should be dug up.