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Last updated: 6 November 2023

Water Source Heat Pump


Water source heat pumps (WSHP’s) are a remarkably efficient renewable energy solution that can reliably provide your property with year round heating, given access to a body of water. With perhaps some of the highest efficiency ratings of any energy system, a WSHP can typically achieve 300% to 600% efficiency, meaning that every 1kW of energy used, will get you 3kW to 6kW of heat energy. 

Granted these energy systems come with their steep price, but their exceptional efficiency and reliable performance can save a household between £395 to £2,000 on annual energy bills, depending on the outgoing system you are replacing.

Already eager to invest in an environmentally friendly, highly efficient energy solution? Let GreenMatch be your one stop shop for all your needs. Instead of dedicating weeks to endless research and vetting, we can connect you with 3 free quotes from our network of trusted local installers. That way you can have home specific tailored quotes delivered right to you, with no obligation to accept. Simply click the button below to begin!

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What is a water source heat pump?

Water source heat pumps (WSHPs) move heat from a source of water to your household in an extremely efficient manner, especially if the water temperature is around 5 to 8 degrees celsius. As such, there are numerous advantages of installing heat pumps.

Depending on the type of heat pump, either the water from a river or small stream is pumped through the heat pump, or a special refrigerant fluid is pumped through pipes laid in a body of water. While both have their own advantages, the latter type requires less maintenance and an easier application process, making it a cheaper option.

Water source heat pumps have been in use since the late 1940s. They use the constant temperature of water as an exchange medium instead of extracting the heat from the outdoor air temperature. Thus, water source heat pumps can reach impressively high efficiencies (300% to 600%) even on the coldest winter nights, in comparison to 175% to 250% for air-source heat pumps on cool days.

The reason these energy systems are so efficient is that they take two kilowatts of free heat from the water and one kilowatt of electricity to produce three kilowatts of heat. This is done with heat going up the flue pipe. As a result, the running costs of heat pumps are low.

How does a water source heat pump work?

The system is made of efficient heat pump units which are interconnected via a loop which the water passes through. Every unit offers specific air comfort requirements in the particular zone they are installed in.

During cold weather, the system  transfers heat from a water loop through the unit’s specially designed refrigerant-to-water heat exchanger and then moves  this heat into the central heating system.

In extreme weather conditions, when a lot more heat is necessary to warm up the building, units are operating in a heating mode; hence, heat is provided to every individual unit from the water of the loop. In case there isn’t enough heat in the looped water, an energy-efficient fluid heater must be installed in the loop to assist the heating process.

Ideally, the water source should be close to the house, so that it would not need to be pumped up to a significant height so the energy required for pumping could be decreased, thus increasing your savings.

Water can be sourced from substantial distances if the pipe diameter is adequately big, especially in a downward direction. When considering installing such a device, you must take into account the permissions and paperwork that must be completed to start your heat pump installation. Still, installing a WSHP is very worth it in the United Kingdom.

Water source heat pump diagram

Below is a water source heat pump diagram to illustrate how these systems function, and what conditions generally need to be met for their installation and optimum performance. The diagram also outlines what an ideal water source heat pump pond size would be, to ensure the system delivers a reliable capacity of energy.

Water Source Heat Pump

If this sounds too good to be true and you are already interested , let us make  your buying process easier. You can avoid searching through endless  suppliers by simply filling in our short contact form and we will provide you with up to 3 free, no-obligation quotes to compare. Click the button below to get started!

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How much does a water source heat pump cost?

When considering a water source heat pump cost,  you must understand  several factors that will affect the cost of your purchase and the long-term return of it.

First, you must consider the initial purchase price of WSHP’s,  which tend to be higher when compared to other heat pumps. The cost incurred for a water source heat pump is around £10,000.

However, this higher cost should be viewed as an investment. The average payback period for domestic water source heat pumps is 5 years, and around 10 years for larger projects. You may even be eligible for assistance in your investment through a heat pump grant

As the optimal lifespan of these systems can reach at least 15 years, you are expected to experience a net benefit of using the system for 2/3rds of its useful life. However, water source heat pumps can last upwards of 50 years with good maintenance, thus, significantly extending the potential payback period.

The net benefit of the heat pump is due to its increased energy efficiency by using waste energy to both heat and cool your property. On average, your energy bills can be  reduced by 15% after installing the system.

When purchasing a water source heat pump, you must also consider the repair costs of the system. This is an important detail to note as proper maintenance can considerably increase the useful life of your heat pump. The repair costs of these systems  are generally lower than their counterparts, but the range is still quite wide depending on the type of repair needed.

Cost and savings comparison table

Note that the Renewable Heat Incentive (RHI) has now closed for new applicants as of 31st March 2022. However those actively on the program will continue to receive their payments until the end of their 7 year accreditation.

YearRHI PaymentsWater Source Heat Pump Accumulated CostGas Boiler Accumulated CostSavings
Needs replacement

It’s also crucial to take the installation costs into consideration when buying a new heat pump. Installation rates can vary a lot from installer to installer, depending on factors like whether they are local to your area or not. This is why we highly recommend you to compare quotes, so you can get a better idea of what a fair price is and choose the best deal possible. However, finding available installers can be stressful and cost you hours of research.

At GreenMatch, we have a network of vetted heat pump installers across the UK. We can connect you with up to 3 qualified installers available in your area, so you can avoid researching them by yourself and wasting your free time. Our service is completely free and non-binding. Click the button below to get your free quotes and choose the best deal now!

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Advantages of water source heat pumps

WSHP’s  are an environmentally friendly and cost-efficient heating option for your home with a variety of benefits:

  • They generate less CO2 emissions than conventional heating systems.
  • Electricity must be used to power water source heat pumps which circulate the water through a loop to capture the heat. For every unit of electricity, you’ll receive between two and four units of heat in return, making heat pumps an efficient and sustainable heating solution. 
  • These systems could save you an estimated £395 to £2,000 a year depending on which heating system you replace.
  • The RHI scheme offers payments to homeowners who have a heat pump, estimated between £2,325 and £3,690 a year for an average four-bedroom detached home.
  • Works well with other heating systems and can be retrofitted.
  • Long lifespan that can range upwards of 50 years with an average length of 15 years.

Disadvantages of water source heat pumps

WSHP’s are a fairly large investment and a homeowner must also consider the potential disadvantages before making the investment.

  • These systems have high upfront costs with an average payback period of 5 years. This makes air source heating cheaper in the short run.
  • The installation of a heat pump can be quite difficult. However, WSHP’s tend to be easier to install when compared to ground source heat pumps.
  • Special planning permissions are required in certain areas.
  • You need to live near a sustainable source of water.

Types of water source heat pumps

When looking for a new water source heat pump, you must consider the different types to determine which one will work the best for you. This is based on a variety of factors such as the proximity of your home to the body of water and if your water source is underground or surface level.

Closed-Loop Water Source Heat Pump Systems

Closed-Loop Water Source Heat Pump

If there’s a sufficient body of water near your house, this will be the lowest-cost option. A supply line pipe goes through the ground starting from the building to the water and intertwines into circles of at least 8 feet under the surface to avoid freezing. Coils must be placed in a water source which meets the minimum requirements in matters of volume, depth, and quality.

Open-Loop Water Source Heat Pump Systems

This system utilises a well or a surface body of water while the heat exchange fluid goes through the heat pump system. Once it disperses through the whole system, the water returns to the ground via the well, a recharge well, or surface discharge.

Open-Loop Water Source Heat Pump

Unfortunately, this option is practical only where there is a reasonable supply of clean water, and at the same time, all regulations and codes regarding groundwater discharge are completed. A filtration system or other forms of water treatment is required to gain the necessary licenses. Furthermore, the heat pump must also use a corrosion-resistant system as a large amount of water is pumped through the pipes.

Environmental legislation to keep in mind

Specific environmental regulations and considerations must be addressed before installing water source heat pumps. Open-loop systems alter the temperature of groundwater, while thermal plumes affect hydrochemistry and bacteriology.

Depending on the type of system you wish to install, licences may be required. For example, hydrogeology and thermal properties have to be investigated, and they require a licence to examine groundwater, and an abstraction licence (permission of diverting surface or groundwater) which can be obtained from the Environment Authority.

WSHP’s work by using underground aquifers as both a heat source during winter and a heat sink in the summer. Aquifers offer good heat conductivity, stable temperatures, and large capacities for heat storage, thus providing you with energy-efficient heating and cooling and a reduced carbon footprint. In the UK, there are plenty of well-suited aquifers for these systems.

Water Source Heat Pumps in the UK

Estimates show that water source heat pumps can produce up to 30% of the UK’s heating needs. Both ground and water source heat pumps combined have obtained a 20% of UK market share for heat pumps. This has been possible due to new developments in the field of renewable energy, lower installation costs, and the Renewable Heat Incentive (RHI). All of these have created massive interest in such systems in general, especially in the London area, with an estimate of 1,000 applications for open-loop systems in particular.

Earn money with your water source heat pump

Since there is a growing importance of using green energy solutions, the UK has started motivating businesses, organisations, and people alike to increase their use of renewables and to reduce CO2 emissions.

Starting mid 2011, the Renewable Heat Incentive (RHI) began providing funds to households with small to medium installations that deliver an acceptable heat load and meet the minimum energy efficiency standard. Water source heat pumps are eligible for the same tariffs as ground source heat pumps.

Unfortunately the Renewable Heat Incentive (RHI) has been closed to new applicants as of 31st March 2022, however those actively on the scheme will continue to receive their payments until the end of their 7 year accreditation, so long as all obligations are met.

With a global projection of rising energy costs, there may be no better time to transition to renewable energy sources. In addition, savings with water source heat pumps – and other renewables – are incrementally increasing every year. With the current July to September price cap in the UK sitting at a favourable £2,074 for an average household, now might be the best time to transition to this impressive renewable energy system.  

Find the best water source heat pump suppliers in the UK

Before purchasing a water source heat pump, you must consider several factors. This can include the initial purchase price of the heat pump, operating costs, and the heat pumps payback period.

Also, you will need to consider maintenance costs and the location of your home as you need to be near an open body of water to operate a water source heat pump. Lastly, when choosing a water source heat pump, you must consider the brand of the heat pump as this will affect the efficiency and lifespan of the product.

There are several popular companies in the UK that manufacture WSHP systems. Here are three top manufacturers with a sizeable presence in the UK:  

  • Kensa is a popular heat pump manufacturer that has a sustained popularity in the UK. 
  • Mitsubishi Electric boasts a WSHP range for both domestic and commercial heating purposes.
  • Daikin is a globally present manufacturer with both domestic and commercial WSHP systems.

After considering all the different factors before investing in a heat pump, we are here to make the buying process easier. Save time and avoid searching for different suppliers by filling in our short contact form to receive free, no-obligation quotes from up to 3 suppliers. Click the button below to get your new heat pump now.

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  • Save up to £1100 per year

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Akif Aliyev
Written by Akif Aliyev, Writer

Akif is a copywriter at GreenMatch since 2023. With a keen interest in community sustainability, green solutions and the role of digital media in identifying climate trends, he aims to hone in on his background in International Studies and Digital Media to provide a multidisciplinary approach to written content rooted in credible research and accuracy.

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