How do Ground Source Heat Pumps Work?
Also known as a geothermal heat pump, Ground Source Heat Pumps are a greener, energy efficient way of heating your home that requires minimal maintenance. Ground Source Heat Pumps (GSHPs) use pipes that are installed and buried in your garden, they then extract heat from the ground which is used to heat your homes radiators, underfloor heating and hot water. Since the ground tends to stay a consistent temperature beneath the surface a Ground Source Heat Pump can be used all year round.
Types of Ground Source Heat Pumps
GSHP’s use a loop of pipes known as a heat exchanger. Here we look at the different types of heat exchangers to choose from.
Horizontal Heat Exchanger
One of the most common forms of heat extraction in the UK for GSHP’s and a much lower cost for installation. This type of heat exchanger is commonly used in residential areas as the excavation for the horizontal loop is usually half the price of vertical drilling. Pipes run horizontally in the ground and one of the main benefits of using this type of heat exchanger is that it can also be laid under driveways or gardens without causing much disruption. The depth in which the pumps are buried has a significant effect on how efficiently they work. Usually, the pipes are buried at 1 to 3m underground. However, loops installed closer to the ground may benefit from the heat from the sun but will drastically cool down faster in winter season.
This kind of GSHP circulates a combination of antifreeze and water around the ground loop, a loop of pipe buried in your gardens grounds. The heat from the ground is then absorbed into the liquid which then passes through a heat exchanger and into the GSHP.
This system is the best choice when buildings or properties are already existing. For installing the pipes small holes are drilled into the ground meaning that gardens and house do not need to be opened up.
Vertical Heat Exchanger
Installing a vertical heat exchanger will take a specialist Heat Pump Company to install this pipe system between 60 – 120m underground. The specialist will be able to determine the size and number of boreholes required by the land, where they need to be installed, heat dispersion and the size of the heat pump. Once the boreholes are drilled, plastic U-pipes are installed, a pressure test is then completed and the hole is then filled with materials that can be pumped up. The cost of digging a borehole is fairly high but once the GSHP is installed there is minimal maintenance required in the future.
This is the second oldest form of heat exchangers which works well if you have a powerful resource to explore. Also known as a direct heat exchange, an open loop system usually requires a site with groundwater or aquifers. When installing an open-loop system two wells are drilled to reach the water source where the pipes are then installed. This system will then pump the water from the first well directly to the heat pump where heat is then extracted. The water is then released back into the ground through the second well.
Benefits of Ground Source Heat Pumps
Heat pumps can help you save money as they are much cheaper to run than direct electrical heating, oil boilers and in some gases cheaper than gas boilers. Alongside this, heat pumps are fully automated and require less work and maintenance than biomass boilers. Here are the main benefits to installing Ground Source Heat Pumps into your property.
Lower your fuel bills especially if you are replacing conventional electric heating.
No fuel deliveries required
Provides heating for your home and heating for your water
Can lower home carbon emissions depending on the fuel you are replacing.
Potential income through the governments Renewable Heat Incentive (RHI)
Saves space as there are no fuel storage requirements
Ground Source Heat Pumps are safe due to the no combustion involved and no emission of potentially dangerous gases.
Planning authorities prefer ground source heat pump systems since they are a safe option that are silent, invisible systems that have a low environmental impact. The Government also favour this type of heating system as it offers a much higher rate of RHI than other renewable options.
Costs and Savings
Installing a Ground Source Heat Pump system can generally cost between £10,000 and £18,000. The general running costs per year will depend on a number of factors including the size of the property and how effective the insulation is.
Your savings will depend on the type of heating system you use currently and what you will be replacing it with. This is affected by:
- Heat Distribution system – Underfloor heating is an ideal option as the water used to heat up the property does not require the water to be hot. However, your heat pump installer will be able to advise you on the best option for this.
- Old Heating System – If your old heating system drained money and was not very efficient then you are more likely to see lower costs running a new heat pump.
- Fuel Costs – You will still need to pay fuel bills with this type of heat pump system as it will be powered by electricity but you will save money on the fuel you are replacing. If you find the fuel you are currently using is expensive you will see a good saving by switching to heat pumps.
Green and Energy Efficient
For every unit of electricity used by this type of heat pump. 3 to 4 units of heat are retained and transmitted. If the Ground Source Heat Pump is installed professionally and securely it can be300-400% efficient in use of electricity. With this type of energy efficiency there will be 50% lower carbon dioxide emissions than for a gas boiler heating system. If the electricity is provided by a renewable energy source then carbon emissions can be reduced to zero.
Is a Ground Source Heat Pump Suitable for you?
Before committing to a Ground Source Heat Pump system there are a few key factors to consider:
- How Insulated is your Home? Ground Source Heat Pump systems tend to work best when producing heat at a lower temperature than your traditional boiler system. Therefore, it is imperative that your home is well insulated with minimal draughts for this system to effectively heat your home.
- What type of fuel will you be replacing? This type of system is highly financially beneficial if you are replacing electricity or a coal heating system. If you use a mains gas this may not be a suitable option.
- What type of heating system will you be using? GSHP’s have a higher performance with underfloor heating systems or warm air heating rather than radiator-based systems due to the lower water temperatures required.
Ground Source Heat Pump Installation
Before installing a Ground Source Heat Pump accurate knowledge of the property is required to help choose the correct heat exchanger suitable for the property. You should consider these factors:
- Soil formation
- House heating and cooling peaks
- Temperature of the ground
Technical knowledge is required for GSHP installation, therefore it is best to consult specialist heat pump companies. For more information on Ground Source Heat Pumps and installation, contact our professional and trained experts today.