5 Best Ground Source Heat Pumps in the UK (2023)

Renewable Energy
A side-view shot of an Ethiopian man turning down a thermostat in his home.

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Ground source heat pumps are a popular form of renewable home heating because they are incredibly efficient at providing low-carbon energy. They work by extracting heat from the ground and converting it to be used by your heating and hot water systems, in turn lowering your energy bills and your carbon footprint.

Unlike air source heat pumps, ground source models require a series of collectors to be buried underground, which makes them slightly more expensive and difficult to install. However, they are often better suited to larger homes than air source models and are usually much quieter, making them an attractive investment for those in detached houses.

In this guide, we review the top ground source heat pump models available in the UK, including their efficiency, cost and pros and cons.

Best Ground Source Heat Pump Systems

  1. Best Overall: Worcester Bosch Greenstore 11 Combi
  2. Best for Large & Commercial Property: Vaillant flexoTHERM
  3. Most Efficient: Kensa Evo
  4. Best Warranty: Ecoforest ecoGEO
  5. Most Powerful: Viessmann Vitocal 350-G

1. Best Overall: Worcester Bosch Greenstore 11 Combi 

Price: £6,495 to £8,800 

Efficiency: A++

Warranty: 2 years

Max Power: 10.2 kW

Worcester Bosch is one of the giants of home heating. Its range of Greenstore ground source heat pumps is highly regarded, highly efficient and offers a wide range of outputs to suit any type of property or heating need. 

Worcester Bosch ground source heat pumps come in two versions: as a combi model or a system model. The combi versions include a built-in hot water cylinder, while the system models must be installed alongside a separate, Greenstore solar-ready cylinder. The combi range will suit the needs of most users and is a little more affordable while being just as strong and energy-efficient.

Worcester-Bosch Greenstore 11 Combi Pros and Cons

Worcester Bosch Greenstore 11 Combi ProsWorcester Bosch Greenstore 11 Combi Cons
Built-in 185-litre cylinderMaximum flow temperature — 20 degrees Celsius — is lower than others on this list
Low energy consumptionHeavier and bigger than other heat pumps due to the built-in cylinder
High efficiency rating
Very quiet

Worcester Bosch Greenstore 11 Combi Key Features

One of the big benefits of the Worcester Bosch Greenstore 11 Combi is its built-in 185-litre cylinder. This means it’s a bit bigger and heavier than other systems on the market, but there’s no need to install a cylinder elsewhere on your property. The Greenstore 11 Combi also offers efficiencies up to 400%. This means that for a single kilowatt of energy, up to 4 kW of energy could be generated for your home.

Other novel features include a room temperature controller and weather compensation technology that monitors the conditions outside and programs your pump to make adjustments if needed. What’s more, its low-energy-consumption design helps keep electricity costs down.

Here are some key features of the Worcester Bosch system:

ModelGreenstore 11 Combi
Output rating10.2 kW
Maximum flow temperature20°C
Warranty2 years
Dimensions 1,800 x 600 x 645 mm
Weight218 kg

Worcester Bosch Add-Ons

Worcester Bosch currently only offers a small range of accessories for its Greenstar traditional boilers. It’s worth checking with local heating supply merchants, too, as they will likely offer accessories you can use with your Greenstore heat pump system. 

Our Opinion of Worcester Bosch

Worcester Bosch is one of the oldest brands in domestic heating. It pioneered the development of traditional boilers, and the company was an early investor in developing renewable energy technology. Its air source heat pumps and ground source heat pumps are built to a very high standard, and all are built to at least an A grade for energy efficiency.

There is arguably no bigger brand in home heating, and no company with a better reputation than the Worcester Bosch group. By investing in one of its systems, you can rest confident in its durability and customer support should something ever go wrong. Of all the brands on this list of the best ground source heat pumps in the UK, Worcester Bosch offers the most options for different home types and energy needs. 

2. Best for Large & Commercial Property: Vaillant flexoTHERM 

Price: From £5,900 to £14,200

Efficiency: A++ to A+++

Warranty: Up to 7 years

Max Power: 19 kW

Long known for its efficient traditional boilers, German manufacturer Vaillant has ventured into the renewable heating systems market and has a number of solid options for homeowners. Its flexoTHERM units are multi-source heat pumps, meaning they can harness power from the ground as well as other sources, such as water or air. 

The Vaillant flexoTHERM range brings the quality German engineering you’d expect from a brand of Vaillant’s standing, as well as extensive product support from Vaillant’s engineering teams. Of all of the heat pumps on this list, Vaillant, as one of the most trusted names in domestic heating, offers some of the best product support.

Vaillant flexoTHERM Pros and Cons

Vaillant flexoTHERM Pros Vaillant flexoTHERM Cons
Extremely quietNot as powerful per unit as other heat pumps on this list
App controlUses boreholes, which are more expensive
Up to 65°C flow temperature
Superb customer service

Vaillant flexoTHERM Key Features

What really sets the flexoTHERM heat pumps apart from others on the market is their near-silent operation. Vaillant’s units have all been awarded Quiet Mark accreditation and emit noise levels equivalent to a standard refrigerator. 

This precision German engineering also delivers in other areas. The flexoTHERM’s vapour-injected compressor provides higher efficiencies and thus more flexibility for your domestic hot water (DHW) system. These compressors are also backed by warranties lasting up to seven years and should run for at least 15 years. 

Here are some Vaillant flexoTHERM key features:

ModelVaillant flexoTHERM
Output rating5 kW up to 19 kW
Maximum flow temperature65°C
WarrantyUp to 5 years
Dimensions 1,183 x 595 x 600 mm
Weight151 – 200 kg

Vaillant Add-Ons

Vaillant offers a number of accessories for use with its flexoTHERM ground source heat pumps. The fluoCOLLECT water-to-water stainless-steel heat exchanger provides water source adaptation, enabling your flexoTHERM heat pump to work as a water source heat pump. There’s also a passive cooling module that provides passive cooling functionality for your flexoTHERM pump. 

Our Opinion of Vaillant 

Vaillant ground source heat pumps are efficient, reliable and quiet heating systems, and the flexoTHERM model is available in a range of outputs. The flexoTHERM is one of the best heat pumps for commercial properties and larger homes, as up to seven individual units can be installed together to meet greater power needs. At the same time, Vaillant’s GreeniQ technology helps ensure maximum efficiency and reliability.

3. Most Efficient: Kensa Evo 

Price: From £5,800

Efficiency: A+++

Warranty: 2 to 5 years

Max Power: 17kW

Based in Cornwall, Kensa has been manufacturing and installing ground source heat pumps since 1999, winning awards for its different designs. Kensa was the first company, in fact, to create a ground source heat pump option for people in small flats and apartments with its Shoebox range. It was also the first manufacturer to create a ground loop array system with individual heat pumps inside properties. 

Kensa’s multi-award-winning Evo range of ground source heat pumps offers a 15% gain in efficiency compared to its previous models, earning an impressive A+++ efficiency rating. For homeowners, this helps minimise running costs and maximise income via the government’s Domestic Renewable Heat Incentive (RHI) scheme. The Evo also features Kensa’s custom-built control panel and system manager, the first of its kind and developed exclusively for use with ground source heat pumps.

Kensa prides the Evo on its simplicity, promising easy installation and setup compared to other systems, and user reviews online generally praise the company for its knowledge and realistic sales pitch. 

Kensa Evo Pros and Cons

Kensa Evo Pros Kensa Evo Cons
Best-in-class A+++ efficiency ratingWarranty just 5 years for core heat pump unit
Third heat exchanger recovers internal waste heat
Stainless steel build and weather compensation reduce corrosion

Kensa Evo Key Features

The Kensa Evo delivers heating and hot water efficiencies of 4.7 SCoP (Seasonal Coefficient of Performance) at 35°C along with significantly reduced noise outputs. Users will benefit from 15% efficiency enhancements over Kensa’s Compact range. The range offers output options from 7 kW up to 17 kW, and with the Evo Kensa introduced a number of performance enhancements.

New self-adjusting, pressure-controlled hot water system and domestic hot water boost controllers synchronise to heat pump cycles to minimise energy use. And there are now integrated water pumps for both the ground side and load side. The Evo also boasts a third heat exchanger to recover internal waste heat from the compressor circuit, thus helping its efficiency. 

Kensa has also opted for a radical new design aimed at simplicity for installation and durability. Stainless-steel heat exchangers eliminate the risk of corrosion, and weather compensation is fitted as standard.

Here are some key features of the Kensa Evo:

ModelKensa Evo
Output rating7 kW up to 17 kW
Maximum flow temperature62°C
Warranty5 years
Dimensions 1,145 x 600 x 575 mm
Weight153 – 170 kg

Kensa Add-Ons

Kensa offers a fairly wide range of accessories for its Evo ground source heat pumps. Most are different installation customisations, from straight and slinky pipes to pond mats, purge pumps, underground and above-ground manifolds, and purging kits. 

Our Opinion of Kensa

The Kensa Evo is best suited for medium to large homes, both existing properties and new-build developments. Heating a home this size, you’ll want the most energy-efficient option available, and the Evo is the best on the market. There is also a good range of output options available to suit specific homes’ needs. Evo models are available in 7-, 9-, 13-, 15- and 17-kW options. 

What’s more, because the Evo is eligible for rewarding payments from the Domestic RHI scheme, you have the opportunity to earn a bit of cash back by using it. Couple that with its minimal maintenance and lack of need for annual servicing, and the Evo is efficient at both in terms of energy and lowering your utility bills. 

To find out which Evo model is best for you, contact the company via its website for a free quote.

4. Best Warranty: Ecoforest ecoGEO 

Price: From £7,000

Efficiency: A++ to A+++

Warranty: Varies

Max Power: 22 kW

Ecoforest was one of the first European manufacturers to develop the technology needed for geothermal heat pumps. The company’s inverter technology that powers its compressors makes the ecoGEO one of the most reliable units on the market. This particular model is one of the more popular ground source heat pumps because it is five times more efficient than traditional fossil fuel systems.

As well as the 5-22 kW model we’re recommending here, the ecoGEO also comes in 1-9 kW and 3-12 kW versions in its Basic range. Ecoforest’s Basic range allows installation with a wide range of DHW cylinders and can even be used with existing cylinders in certain situations, giving you great flexibility of design. Costs range depending on the size of your home and system needs. Reach out to your local supplier to get a free quote for your bespoke system.

Ecoforest ecoGEO Pros and Cons

Ecoforest ecoGEO Pros Ecoforest ecoGEO Cons
Up to 70C flow temperatureRequires extensive groundwork
Quiet operationAntifreeze needs replacing every three or so years
Strong compressor increases energy savings

Ecoforest ecoGEO Key Features

Ecoforest’s ecoGEO is the most powerful option on our list of the best ground source heat pumps in the UK. It brings a heating capability of up to 22 kW on a single-phase supply. Users also appreciate its quiet operation and compact installation.

A High Temperature Recovery system allows for DHW production at up to 70°C without electrical support, as well as simultaneous production of DHW and heating/cooling. The open-loop system also includes integrated management of four different emission temperatures, dual buffer tanks for heating and cooling, one DHW tank, one pool and hourly control of DHW recirculation.

Ecoforest’s ecoSMART advanced controls also let you set your home’s heating even when you’re not there. As well as heating and air conditioning your home, the ecoGEO can also heat your swimming pool.

Here are some key features of the Ecoforest ecoGEO:

ModelEcoforest ecoGEO
Output rating5 kW to 22 kW
Maximum flow temperature70°C
Warranty7 years
Dimensions 1060 x 600 x 720 mm
Weight186 – 194 kg

Ecoforest Add-Ons

Ecoforest offers a couple of accessories that can enhance your ecoGEO heat pump system. Its AU range of air source units comes in multiple power options (50 kW / 100 kW / 150 kW) and can be used in conjunction with your ecoGEO ground source heat pump. When running multiple sources of energy capture like this, Ecoforest also offers its ecoSMART e-manager.

Our Opinion of Ecoforest

The Ecoforest ecoGEO is the one of the best ground source heat pumps for people with large properties or high heat loads. You should also consider the ecoGEO even if your home is smaller but you would like to expand into the loft or build an extension at a later date. The ecoGEO’s 22-kW output is one of the best in the marketplace for residential ground source heat pumps, and the company has even more powerful options for those with commercial properties to heat. 

5. Most Powerful: Viessmann Vitocal 350-G 

Price: £17,800 to £22,300

Efficiency: A++

Warranty: Up to 7 years

Max Power: 42.3 kW single-stage / 85.6 kW two-stage

Like Vaillant, Viessmann is a trusted brand in the home heating industry. Long a manufacturer of traditional boilers, it has expanded into ground source heat pumps and has options to cover a wide range of needs. The company’s Vitocal models are some of the most popular ground source heat pumps due to their power and efficiency.

The Viessmann Vitocal 350-G is the most powerful model in the range, providing single-stage heating outputs from 20.5 to 42.3kW and two-stage from 41 to 84.6kW. The two-stage can also achieve flow temperatures of up to 70°C thanks to its powerful EVI (enhanced vapour injection) refrigerant circuit compressor. The novel device uses an enhanced vapour injection to cool the refrigerant so that it can be more densely compressed. This enables the Vitocal 350-G to deliver temperatures high for modernisation projects and radiator heating systems.

Viessmann Vitocal 350-G Pros and Cons

Viessmann Vitocal 350-G Pros Viessmann Vitocal 350-G Cons
Low running costsOne of the more expensive units you can buy
Up to 70°C flow temperature (65°C for single-stage unit)
Quiet operation
Extremely powerful

Viessmann Vitocal 350-G Key Features

What’s unique about the Vitocal 350-G is that for higher heat demands, you can pair units in a primary-secondary arrangement and extend their power. For instance, with two Vitocal BW 351.B42 units at 42.3k W each, you double your output to 84.6 kW. This makes the Vitocal 350-G range by far the most powerful ground source heat pump for residential use. And thanks to its EVI compressor, the Vitocal 350-G can achieve an extremely high seasonal coefficient of performance (SCOP) of 5.4, which contributes to its ultra-low running costs.

It also boasts a low-vibration design, making it one of the quieter options at this output segment of the market. The Vitocal 350-G range also includes water/water heat pumps that let you push your output all the way up to 104.6 kW.

What’s more, the Viessmann Vitocal 350-G comes already equipped to utilise power from a photovoltaic system should you install one of these as well. An intelligent control unit increases on-site consumption of power generated from your solar panel system. 

Here are some key features of the Viessmann Vitocal 350-G:

ModelViessmann Vitocal 350-G
Output rating20.5kW to 42.3kW
Maximum flow temperature65°C (single-stage) / 70°C (two-stage)
WarrantyUp to 7 years
Dimensions 1085 x 780 x 1,267 mm
Weight315 kg

Viessmann Vitocal 350-G Add-Ons

Viessmann offers a couple of extras you can use with the Vitocal 350-G units. The Vitoconnect 100 is a WiFi interface that enables you to remotely operate your heating system via the ViCare app, as well as supporting remote maintenance.

The ViCare app allows you to adjust heating times from anywhere, as well as see a running tally of your cost savings.

Our Opinion of Viessmann 

The Vitocal 350-G range is really best suited for people who need a lot of heating power. It’s perhaps the best ground source heat pump for families living in a fully detached home. All of those external-facing walls will mean higher heat demands, and a Vitocal 350-G will certainly deliver. Other large residences or restoration projects will also benefit from this type of power. 

As well as being powerful, the Vitocal 350-G also does a lot of other things well. It’s one of the more efficient ground source heat pumps, meaning your running costs will be low. We also like that it’s compatible with solar panel systems. The best solar panels should work in tandem with your other green energy systems. Viessmann has planned ahead for you and made your transition to solar energy seamless.

Ground Source Heat Pumps Verdict and Recommendation 

When choosing the best ground source heat pumps in the UK, we looked at a variety of factors, including output, efficiency, warranty length and, of course, price tag and operating costs. For overall build quality, performance and value for money, Worcester-Bosch’s Greenstore tops our list. The company has been in the game a long time, and its systems are not only incredibly durable, but they also offer flexibility and can future-proof your home. 

We love that the Greenstore combi range comes with a built-in 185-litre cylinder. Sure, it’s a bigger unit than other ground source heat pumps in the UK, but it streamlines your system and eliminates the need to install a separate cylinder. And if you envision installing solar panels on your home in the future, investing a little more into the company’s Greenstore system range allows you to connect the two systems to work in tandem when that time comes. 

This flexibility expands when you consider the range of output options available — 5.4 kW up to 10.2 kW — and the minimum A+ efficiency ratings of all of the units in the range. In our view, and for your money, there is no safer bet than a Worcester-Bosch Greenstore ground source heat pump system. 

Of course, other homeowners have more specific needs. You might live on an exceptionally large property, or maximum efficiency might matter most to you. To this end, we looked at the whole of the market to see which ground source heat pumps best meet some of those more niche needs. 

How Much Does a Ground Source Heat Pump Cost?

Because every home and its energy needs are different, prices really vary. The cost of a ground source heat pump system is also dependent upon where you live and what rates your local installers will charge. Generally, though, a typical ground source heat pump system will range from £8,000 upwards. 

Remember: this doesn’t include installation. The total cost of installing a ground source heat pump in the UK after labour can run from £15,000 up to £30,000, depending on the size of your property.

However, there are ways to make this more cost-effective. For starters, ground source heat pumps fall within the Domestic Renewable Heat Incentive. This scheme pays homeowners for any heat they generate with renewable energy. These payments continue for seven years after the date of installation. What’s more, a ground source heat pump system qualifies for the UK government’s Green Homes Grant, which will contribute up to £5,000 per household toward installation. 

When you factor in the grants, the RHI payments and that ground source heat pumps are cheaper to run than traditional gas heating, over time, you should make back your investment and then some. 

Frequently Asked Questions: UK Ground Source Heat Pumps

Here are some common questions about ground source heat pumps:

What are the disadvantages of ground source heat pumps?

High installation costs are really the only major downside of ground source heat pumps. The installation costs will dwarf the price you’d pay for a traditional boiler, but you need to remember that after the initial investment, the running costs are quite low. Over time, you’ll also save money due to their high efficiencies, which will help you make back your investment. What’s more, there are many grants available to help with that initial installation cost.

How does a ground source heat pump work?

A ground source heat pump works by extracting heat from the ground and transporting it to your central heating system via a network of underground pipes. When you get deep enough underground, the earth has a constant temperature of around 10-12°C. The soil heats these pipes, and you can harness this heat for your radiators, hot water or whatever heating elements you use. 

What type of home is best for a ground source heat pump?

New-build homes are better candidates for ground source heat pumps than older houses. This is because it is a lot less costly and more straightforward logistically to install a system while a house and garden are being developed than to tear apart an existing framework. If you do have an older home and still want a ground source heat pump, you need to ensure your garden is big enough to support a system that can heat your home. Your local supplier can advise you on your garden’s suitability when you reach out for a free quote. 

What is the life expectancy of a ground source heat pump?

Though warranties tend to range from two to five years, most mass-market ground source heat pumps should last you around 20-25 years. This is about double the life of a traditional combustion boiler. What’s more, the ground heat exchanger element of the system is engineered to last for more than 100 years. The exchanger is the most expensive part of your ground source heating system.

Can you use a ground source heat pump in the UK?

You may be thinking that for ground source heat pumps, UK weather isn’t suitable. It’s true, the UK isn’t a warm climate. But even in a temperate climate like ours, the earth stays at a fairly constant warm temperature all year round. This means ground source heat pumps are not only highly efficient but also very stable systems for heating your home. What’s more, their energy output is around three to four times greater than the energy required to run them.

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