Ground Source Heat Pump How it Works

Find out everything you need to know including how they work, how efficient they are and why they are a reliable form of renewable energy.

What is a Ground Source Heat Pump (GSHP)?

GSHPs are an alternative heating system to conventional gas or oil boilers. They are units which are installed inside a property or in an external plant room and they circulate heat from the ground and raise its temperature before distributing the heat to provide hot water and space heating via radiators, underfloor heating or fan coil units. They are powered by electricity and are a clean and combustion free technology which doesn't use fossil fuels.

   Commercial Ground Source Heat Pump Installation example GSHP Install Example

(Images: MasterTherm AquaMaster Inverter ground source heat pump installation examples)

How Does a Ground Source Heat Pump Work?

A ground source heat pump system is connected to a series of pipes laid in the ground, these are known as ground collectors, ground loops or ground arrays. The pipes can be laid either horizontally in trenches or vertically in boreholes. A water and refrigerant mixture is circulated through the collectors absorbing heat energy from the ground, when it reaches the heat pump a compressor raises the temperature to a usable level and it’s then passed through a heat exchanger from which it's distributed to your hot water tank and radiators for hot water and heating.

Many people find the idea of the pipes in the ground collecting thermal energy an unusual concept. An easy way to think about it is if you have a chilled plastic bottle of water and put it into a room of normal temperature, it will eventually absorb the heat energy of the room changing it from chilled to room temperature. The same thing is happening underground with the ground collectors - water is being circulated through the pipes and absorbing the thermal energy from the earth around them.

Learn more about how ground source heat pumps work.

Ground Loops Ground Collectors Borehole Drilling Rig Borehole

(Images: Horizontal ground loops, straight pipe ground collectors, borehole drilling rig, borehole)

What are the Main Benefits of Installing a Ground Source Heat Pump System?

  • Clean and combustion free
  • Excellent efficiencies of up to 400%, reducing your energy usage
  • Heat pumps use energy from the ground and need just a small amount of electricity to operate, this means your carbon footprint is greatly reduced 
  • If the electricity comes from a renewable source such as solar or wind, the system will be carbon free
  • Capable of also providing passive and active cooling which saves time, money and space compared to installing two separate systems
  • Capable of integrating with other renewable technologies such as solar and battery storage
  • Long lifespan of around 25-30 years for the heat pump and 100+ years for the ground collectors
  • Intelligent zone controls and the ability to simultaneously heat one room whilst cooling another (ideal for different temperature preferences or for commercial manufacturing processes)
  • More advanced - ability to integrate with smart tariffs and self optimise to save energy and money
  • Renewable Heat Incentive payments

What are the Disadvantages of Ground Source Heat Pumps?

  • We’ll be frank with you, the biggest disadvantage to installing a ground source heat pump is the cost. They are are not yet mass produced on the same scale as gas boilers, making them more specialist. However this won’t always be the case.
  • Land disturbance is the second and only other disadvantage. In some cases your lawn or patio might need to come up or if you’re laying trenches in a field you might need to leave some time for the grass to grow back. Many customers turn this into a positive and use this as an opportunity to landscape their garden in a different way.

How Long Does it Take to Install a Ground Source Heat Pump?

It takes around 2-4 weeks depending on the size of the property and what the existing heating system is. Newbuilds are quite straightforward as each part of the install can happen as the building starts to take shape e.g. the groundworks team will often be very first on site to dig the trenches or drill boreholes and then plumbing and electrical engineers will be on site once the rooms have been created so that the heat pump, water tank and radiators can be installed.

How Much Space is Needed for a Ground Source Heat Pump?

This is one of the most frequently asked questions surrounding heat pumps. We want you to have all the information you need whilst researching GSHPs, which is why we’ve created an article covering this topic

How Much Does a Ground Source Heat Pump Cost?

Cost is also a common question and our dedicated article includes pricing examples, information on how much maintenance is required, how long the system lasts and funding options. 

How Will Installing a Ground Source Heat Pump Affect My Heating Bill?

Ground source heat pumps are incredibly efficient, to give you an idea a new gas boiler has an efficiency of around 90% whereas a GSHP has an efficiency of around 300-400%. This means the energy you’re using goes further, so you need less of it. When you’re using less energy your monthly bill is reduced, we’ve had customers who have seen a 75% decrease in their monthly energy bill.

Because heat pumps automatically self-optimise, you can use them in conjunction with smart tariffs like Agile Octopus. Agile Octopus publishes half hourly tariff rates a day in advance giving users the ability to use energy when it costs less to save money. A MasterTherm heat pump can ‘read’ this tariff and automatically self-optimise to run at times when electricity costs less whilst still achieving your preferred temperatures. With MasterTherm your user interface (what you use to control your heating - like a thermostat) will even show you how much energy your system is using, how much it costs during that half hour period and whether that price is high, low or average so you have complete visibility.

What Are the Most Important Factors to Consider When Installing a Ground Source Heat Pump?

  • Insulation - you’ll need to ensure your property is well insulated before installing a heat pump, this helps to avoid heat loss and ensures the system can work as efficiently as possible
  • SCOP rating - this stands for (Seasonal coefficient of performance) and the higher this number is the more efficient the heat pump. The more efficient your heat pump, the more you’ll save on your energy bill
  • MCS approved - make sure the heat pump is an MCS approved product and that your installer is MCS approved. This will give you protection if anything goes wrong with your installation and also ensures you’re able to claim financial initiatives such as RHI 
  • System design - make sure your installer carries out heat loss reportsand heat load reports. Design is fundamental as an undersized system means your heating may not reach your desired temperatures and will be working harder, reducing efficiency. An oversized system is unnecessary and will cost more both for the actual heat pump and for monthly energy bills than a correctly sized system.
  • Find a skilled installer - If your installer carried out a site visit and system design you're on the right track, but also ask to see photos of their previous installations and check their customer reviews. Some installers may offer the chance for you to see an existing install and speak to an existing customer.
  •  Aftercare - Does your installer and the heat pump manufacturer offer aftercare and technical support? Heat pumps do operate differently to gas boilers and it’s always helpful to know someone is just a phonecall away if you have a question or you’re unsure if your system is working correctly. At Thermal Earth we supply MasterTherm heat pumps which are enabled with remote diagnostics so we can see how your system is performing and often correct any faults without ever needing to carry out a call out (saving you having to wait at home for an Engineer).


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