How Ground Source Heat Pumps Work: A Comprehensive Guide

With the UK government striving to meet strict energy efficiency targets for 2050, homeowners are being encouraged to invest in more efficient forms of heating.

One of the main alternatives to gas heating currently being discussed is ground source heat pumps. They are highly efficient and a great solution for homeowners looking to reduce their carbon footprint.

With the popularity of ground source heat pumps likely to increase as efficiency efforts continue, it’s important for homeowners to have a firm understanding of how these systems work, their benefits, and their potential costs.

Find out everything you need to know about ground source heat pumps in this informative guide.

What is a Ground Source Heat Pump?

Ground source heat pumps (GSHPs) are an energy efficient form of heating which extract heat from underground temperatures and use this energy to provide heating to your household.

UK underground temperatures usually range at around 11°C – 12°C. GSHPs absorb this natural heat to provide a more energy-efficient and renewable way of heating properties.

Types of Ground Source Heat Pump

There are two main types of ground source heat pump, these include:

• Closed-loop systems – These are the main type of ground source heat pump in the UK. They come in horizontal and vertical forms.Horizontal systems are typically best suited to homes which have a sufficient amount of garden space, as the ground loops are placed around 1-2 metres deep.Vertical borehole systems are typically a better option for properties that don’t have enough garden space for a horizontal system. With this option, heat is absorbed from further into the ground. Pipework is placed around 50m – 150m deep. This option tends to be more expensive than horizontal closed loop systems.
• Open-loop systems – This type of GSHP involves groundwater being pumped from an aquifer and sent to the system’s heat pump for an evaporator to extract its natural heat. Once this process is completed, the groundwater is then dispelled back into the ground.

How Do Ground Source Heat Pumps Work?

Ground source heat pumps work by using pipes that are buried in your garden to absorb heat from the ground. A mixture of water and antifreeze is circulated around the underground loops of pipe, natural heat is absorbed, then the solution is passed through a compressor which raises its temperature. The mixture is then sent through a heat exchanger which extracts the heat and transports it to your heat pump for heating and hot water purposes within your home.

Once cooled, ground-loop fluid is sent back underground to absorb more energy in a continuous process to provide heating as required.

How Much Do Ground Source Heat Pumps Cost?

Ground source heat pumps can be costly to install onto properties. They are more expensive in comparison to air source heat pumps. It is estimated that these systems can cost up to £19,000 to install, depending on the size of the pump required and the complexity of the installation process. However, you should bear in mind that you could make significant savings with a ground source heat pump– over time you should be able to make the installation costs back with surplus!

In terms of GSHP running costs, these will depend on the size of your property and its level of energy efficiency. Many homeowners decide to invest in new radiators and/or underfloor heating as these tend to work well with GSHPs. Although these extra systems will add to your overall installation costs, they will help to enhance your quality of heating and could thus be deemed as a worthwhile investment.

Is There any Government Funding Available for Ground Source Heat Pumps?

The government offers a number of funding schemes to help homeowners cover the cost of installing energy efficient systems like ground source heat pumps. If you’re considering getting a GSHP installed, you may be eligible for funding through the following schemes:

1. Green Homes Grant Scheme – This scheme provides eligible applicants with vouchers for up to two thirds of their installation costs. Standard contributions are up to £5,000, although some applicants may be eligible to receive up to £10,000.
2. Renewable Heat Incentive  – Through this incentive scheme, you could receive quarterly payments across seven years for the heat that you generate through your renewable system.

Pros and Cons of Ground Source Heat Pumps

To help you decide if a ground source heat pump is a suitable option for your home, below we outline some of the main advantages and disadvantages of this form of heating.

Pros of Ground Source Heat Pumps

• Energy efficiency – Ground source heat pumps don’t require a significant amount of energy to provide heating to your home. GSHPs can be 300-400% efficient. They could also help to reduce your carbon dioxide emissions by 70% in comparison to gas boiler systems.
• Savings – Initial investment costs for GSHPs may be expensive, but their lower running costs can help you save significantly in the long-term. It is estimated that these systems can help you save up to 50% on heating costs.
• Eco-Friendliness – Although GSHP’s do require some electricity, they are still considered eco-friendly and renewable. For every kW of electricity that the heat pump consumes, around 3-4 kW’s of heat is generated.
• RHI payments – Getting a ground source heat pump installed could make you eligible to receive payments through the government’s Renewable Heat Incentive Scheme.
• Can also provide cooling – GSHPs are also capable of providing air-conditioning. To achieve this, one of the system’s valves needs to be reversed in order to change the direction in which the fluid is circulated.
• Less noise –GSHPs typically emit less noise than other forms of heating such as air source heat pumps and old gas boilers.
• Long lasting and reliable – A GSHP can have a working life of over 20 years. Regular servicing can help to keep your GSHP functioning effectively for as long as possible.

Cons of Ground Source Heat Pumps

• Expensive installation costs – Despite offering long-term savings, the initial costs of getting a ground source heat pump installed can be high. In some cases, you may also have to retrofit your property to increase the quality of heating, which will add to the overall costs.
• Can be disruptive – The groundwork required for GSHP installation is likely to cause some disruption. Planning permission may also be required.
• Location specific – GSHP systems are typically best suited to properties that have sufficient outdoor space. They can therefore be unsuitable for those who live in built-up areas.
• Liquids used can be environmentally-unfriendly – Some concerns have been raised about the liquids used by GSHPs during the heat transfer process. To ensure that your system works effectively, you should ensure that it is installed by a qualified heating professional.

Is a Ground Source Heat Pump Suitable for Your Home?

In the past, ground source heat pumps were deemed as a primarily suitable option for new build properties, due to the scale of work and upheaval required.

However, with the government aiming to increase household efficiency and a potential gas boiler ban on the way, ground source heat pumps are being promoted as an effective form of heating for all kinds of properties.

If you’re seeking to increase your household’s energy efficiency, and your property has a sufficient amount of garden space, a ground source heat pump could be an ideal heating solution for you.

If your property does not have enough space for a ground source heat pump, other alternatives to gas heating are available.

Frequently Asked Questions (FAQs)

What are the disadvantages of ground source heat pumps?

GSHPs have some disadvantages, including the following:

• Expensive to install
• Most effective only for underfloor or air heating systems
• Their installation process involves significant work and disruption to your property

Can cause electricity bills to go higher. They need electricity to heat the home which will inevitably increase your electricity demand.

Can I get a ground source heat pump?

You can most definitely purchase a ground source heat pump. If you are looking to purchase a ground source heat pump in the UK, there are many ground source heat pump manufacturers you can opt for. These include Bosch, Carrier, and Dandelion Energy.

Is a ground source heat pump worth it?

GSHPs are better suited to new properties than retrofitting into an existing home. This could be due to reduced costs if the heat pump is included as part of the building’s specification, instead of having to fit underfloor heating later. If you are using the system for your hot-water supply, then running costs can be higher and you might need a supplementary electric immersion heater for your heating needs. The ground loop element will need a bit of maintenance. These often come with warranties of around two to three years but are meant to operate for over 20 years.

How much does a ground source heat pump cost to run?

A four-bedroom house will probably need around 11,000kWh of heat for space heating and 4,000kWh for domestic hot water. Assuming a SCoP (Seasonal Coefficient of Performance) of 4.5, the property will need 3,334kWh of electricity to run it. Taking electricity to be around 15p/kWh (including VAT, standing charges etc) gives a running cost of £500 per year.

How much does a ground source heat pump cost?

On average, a homeowner can expect to invest about £9000 to £22,000 on a GSHP. This would cover a complete geothermal installation. The cost can range from £22,000 to £33,000 for high-end ground source heat pump systems for large homes.