Ground Source Heat Pump
Ground source heat pumps are a common type of heat pump.
They’re environmentally-friendly, effective and help save money on heating bills.
The heat pumps are also a great investment for their eligibility for government incentives.
The installation costs are high, but the system can help save up to 50% on heating bills in the long run.
However, the initial costs of this investment depend on certain factors.
Ground source heat pumps are further classified, including close and open-loop systems.
If you’re skeptical about installing a ground source heat pump, you might want to consider the benefits you stand to enjoy with the system.
The advantages of ground source heat pumps include saving money and longer lifespan. We’ll look deeply into the advantages later on in this guide.
How Ground Source Heat Pumps Work
Every heat pump system works by absorbing heat from a source and transferring it to the house where it’s needed for heating.
The source where the heat comes from gives the name of the system.
For a ground source heat pump, the heat source is the ground. The system works by generating heat from the ground and sending it into the home.
Ground source heat pumps are effective since the energy – heat – coming from the sun goes straight into the earth, which remains constant throughout the year.
The system is a great investment in the UK since the earth’s temperature a few meters below the feet is around 11°C.
Ground source heat pumps are a great tool for making the UK’s Net-Zero target by 2050 a reality.
What Is A Ground Source Heat Pump?
Again, ground source heat pumps function by extracting heat from the earth and transfer it to the home. It’s an effective option for both space heating and domestic water heating.
The system comes with various modules: the distribution system, the pipes, and the underground heat exchanger.
The heat from the ground is conveyed to the heat exchanger by the antifreeze-water mixture that runs in the pipe.
The heat from the ground continuously heats the mixture to keep the mixture at a high temperature.
The exchanger absorbs the heat and sends it to a refrigerant that boils at a low temperature to turn it to a gas.
The compressor takes the job from there and compresses the gas into a higher temperature and sends it to a condenser.
The condenser does the final job by distributing the high-temperature energy to the house’s central heating systems, such as showers, faucets, radiators, and under-floor heating.
Ground Source Heat Pumps: A Suitable Option For My Home?
To know if a ground source heat pump is a suitable option for your home, it’s smart to do some research.
A part of this research is to obtain an Energy Performance Certificate.
This certificate helps know the right sizing for your home to decrease heat loss, hot water needs, and energy consumption.
Ground source heat pumps have two types of loop systems: open-loop and the closed-loop systems.
The open-loop system extracts both the water and heat through a heat pump, and the heat is later extracted while the water is sent back.
The closed-loop system draws the heat directly from the ground using a continuous piping system.
Closed-loop systems are further divided into types:
Horizontal Ground Source Heat Pump
This variant of the closed-loop GSHP involves digging holes that are approximately 1-2 meters deep, where the heating system is laid.
Since this method consumes much space, it’s more suitable in rural areas with more land.
The required area for the installation depends on the depth to bury the loop, the climate, the soil moisture, and the efficiency of the heat pump. A 200m2 home will require 400 to 800m2.
Vertical Ground Source Heat Pump
This is a more suitable choice in areas with limited land, though it’s more expensive.
In this variant, the hole is dug about 6m into the ground, and the total piping depth varying between 50-150m, depending on the heat requirement and the composition of the ground.
Closed Loop System for Pond/Lake
This is only a better option in areas with poor water quality to install an open-loop system.
Most UK homes prefer the open loop because the closed-loop system requires almost a body of water.
Price of Ground Source Heat Pumps
Ground source heat pumps have the highest price of all heat pumps, but the energy-saving benefit it offers is a great compensation for the high price.
If you’re planning on installing a ground source system on your home, you might need to budget be up to £30,000 to £40,000, depending on certain factors, such as your energy needs and the size of your home.
The running cost is also a factor to consider. This system’s running cost depends on how well your home is insulated and, again, your home’s size.
Since installing a ground source heat pump may require other heating elements, such as under-floor heating system or radiators, it’s key to put them into account as well.
If your installation requires any of these and you don’t have it installed or damaged, a new installation or repair will add to the upfront costs.
Groundwork Costs of Vertical vs Horizontal Systems
The groundwork costs for each type of system vary.
The vertical installation is more expensive than its horizontal counterpart.
However, it’s great to bear in mind that the horizontal installation requires a large land area – at least half an acre of land.
How Efficient Are Ground Source Heat Pumps?
Ground source heat pumps have high Coefficients of Performance (COP).
The average ground source heat pump has a COP of 4.
This means that the average ground source heat pump will produce 4 times the amount of electricity consumed, such as 4kW of heat for 1kW of electricity.
The GSHP system utilizes heat from the ground to heat the home with little electricity consumption.
The energy from the sun heats the groundwater, which stabilizes the temperature of the earth’s floor all year round.
It seems impossible to give a specific efficiency of a ground source heat pump since the value is influenced by the type of soil it’s installed, and soil properties in the UK vary.
As such, you’ll need to consult a profession installer to examine your property to know the specific efficiency to expect from your system.
How Efficient Are Heat Pumps in Cold Weather?
Depending on the variant of ground source heat pump, cold weather doesn’t have much effect on the system.
Cold weather almost has no effect on vertical GSHP but may affect horizontal GSHP a bit.
In vertical GSHP, the pipes are buried meters deep into the heart, which helps their temperature relatively high.
How Do the COP and SCOP Relate to Efficiency?
Again, ground pump systems have high-performance coefficients – between 3 and 5.
The Coefficient of Performance (COP) of a heating system is the unit of heat generated with one unit of electricity.
That is, how many kW of heat energy a 1kW of electricity generates.
When a ground source heat pump generates 3 kilowatts (kW) of heat from 1 kilowatt of electricity, we say the system has a COP of 4.
While the COP gives the average efficiency of the system, the Seasonal Coefficient of Performance gives the efficiency for each season of the year, which sounds more accurate.
Advantages and Disadvantages of GSHP
One common reason most people run from installing a heat pump is that several acres of land are needed for the installation.
This is not true, as you can install the system in your small garden and still enjoy its full benefits.
However, this doesn’t mean that the system doesn’t have its disadvantages. Here’re the advantages and disadvantages of ground source heat pumps:
- High energy-efficient
- Low running cost with little maintenance
- Less noise than air source heat pumps and gas boilers
- Environmental friendliness
- Longer lifespan
- Higher costs of installation compared to air source heat pump systems
- Can be influenced by the type of bedrock
- Requires large areas of land
- Suitable for new-builds than retrofits
- Some toxic liquids on the market
Installation of Ground Source Heat Pumps
The first task in installing this system is to know which type is best for your home.
To know this, the house size and requirements are put into account.
After choosing which type to install comes the phase of evacuating the loop fields.
Installation of a vertical ground source system involves digging the ground up to 100m deep.
After this, the loop is placed in the hole while the exchanger is installed to extract heat from the ground.
A horizontal installation doesn’t require digging deep into the earth but requires a large space to place the loops.
How Much Space Does a Ground Source Heat Pump Require?
Again, horizontal GSHP systems require having large space to place the loops.
The average UK family will need to lay around 600 meters of loops in the ground, which requires around 700 m2 to dig up.
Surface area is not always a concern with vertical systems as they only require digging the ground some meters deep into the earth.
The system size is a significant determinant of the depth of the borehole. An average ground source system of 8kW would require up to three boreholes.
Installation: How Long Does It Take?
Installing a ground source heat pump doesn’t take much time.
The only aspect that takes much of the time is land preparation.
Once the land is prepared, the pipe can be laid in just a day or two.
For vertical GSHP, the borehole can be drilled within 3 days, after which the device itself is installed and connected to the house’s central heating system.
Combining Heat Pumps with Renewable Energy
Running a heat pump requires a source of electricity.
If the energy source for running the system is not a renewable source, it means the system is not entirely carbon neutral.
As such, powering it with renewable energy is the best way to go, and solar panels are a perfect option. Combining heat pumps with solar panels helps achieve a full carbon-neutral system.
Is Planning Permission Needed for a Ground Source Heat Pump?
Whether you’ll need planning permission or not depends on the country and the region your home is.
While installing the system requires special permissions in Northern Ireland and Wales, some regions in Scotland and England don’t need permissions, depending on the size of the property though.
Are GSHP Systems Eligible For Grants?
Installing the ground source heat pump helps qualify for the Renewable Heating Incentive.
With this incentive, owners can save money on every kilowatt of energy generated with their heating system. Currently, the scheme pays 21.17 p/kWh of energy generated by the system.
Once the system is installed, payments start rolling in quarterly for seven years.
This grant’s payments depend on certain factors, such as the current tariffs and the technology used.
The RHI is divided into two: domestic and non-domestic renewable heat incentives.
While the domestic renewable heat incentive aims to promote renewable installations in residential homes, the non-domestic grant is focused on helping the installation in businesses and commercials buildings.
The RHI was expected to close in March 2021 but has been extended to March 2022.
However, a new grant – Clean Home Grant – is to take off the role of RHI and will kick off in April 2022.
However, it’s important mentioning that this grant doesn’t apply to installations in Scotland, Northern Ireland and Wales but only to eligible installations in England.
The grant offers a voucher of up to £5,000 on every eligible renewable heating system.
Another benefit you might be qualified for as an owner of a ground source heat pump is VAT reduction.
However, this benefit is only available to landlords and homeowners above 60 years who’re beneficiaries of disability benefits.
This offers a 5% tax reduction, which may apply only to the installation or the whole product, depending on the costs.