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What is a Water Source Heat Pump?

No to gas boilers

Air and ground source heat pumps are the most popular choices of heat pump for anyone looking for a renewable heating system. Properties in close proximity to an outdoor water source have a third type to consider: water source heat pumps.

What is a water source heat pump?

Rather than extracting heat from the air or the ground, like the more common heat pumps, water source heat pumps take heat from outdoor water sources, such as rivers and lakes.

During the day, the sun's energy is transferred to the water of lakes and rivers which, with a water source heat pump, can be extracted and used to provide a property with heating and hot water.

How water source heat pumps work

Water source heat pumps take the solar energy stored in an outdoor water source and convert it into heat that can be used for central heating and domestic hot water. There are 2 types of system that work in different water: closed-loop and open-loop.

Closed-loop system

A liquid refrigerant, that's able to absorb heat, is circulated through pipes buried 8 feet underground running from the building to the body of water and back again.

This system means that water doesn't have to be taken from the water source, unlike open-loop systems.

Open-loop system

An open-loop system removes ground water from the water source and transports it to the heat pump installed in the building. When the water reaches the heat pump, it's compressed so that the solar energy can be extracted and used for central heating and hot water.

As water is extracted from the water source, you may need to seek approval and be granted a licence.

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Advantages of water source heat pumps

If you live close enough to an accessible water source to make the installation possible, there are many benefits of a water source heat pump:

  • Only need a small amount of electricity to operate
  • Produce fewer emissions than conventional heating systems using gas and oil

Some of the advantages they have over air and ground source heat pumps include:

  • Smaller than ground source heat pumps
  • Produce more heat during the year than air source heat pumps
  • During the winter, there's more heat in water than air
  • Heat is transferred at a faster rate than from the air or ground

Disadvantages of water source heat pumps

In addition to the many benefits to water source heat pumps, there are some major considerations and factors that might completely rule out the installation of one for your property:

  • Your property needs to be within a few hundred metres of an open water source
  • Open-loop systems need to be approved before the installation can take place
  • Need an electricity supply

Most properties in the UK are much better suited to an air or ground source heat pump and these are the reasons why:

  • Often the most expensive type of heat pump
  • Installation can take up to 16 weeks, much longer than other heat pumps
  • More UK properties suit air or ground source heat pumps than water source heat pumps

How much do water source heat pumps cost?

More often than not, a water source heat pump will set you back more than an air or ground source heat pump would do. Before taking into account the installation costs, a water source heat pump will cost in the region of £10,000.

What is an air source heat pump?

Air source heat pumps extract heat from the air outside to provide heating or hot water, depending on the type of system, to a property, even in temperatures as low as -15C.

Some outdoor space will be needed to install the heat pump, which includes a fan that brings in the outdoor air. Put simply, air source heat pumps work much like fridges but rather than producing cold air, they're able to generate heat.

What is a ground source heat pump?

Underground temperatures sit at around 10-15C all year round and a ground source heat pump is able to use this heat to provide a home with central heating. A fairly large amount of outdoor space will be needed as the underground heat is captured using pipes than need to be buried around 2 metres below ground level.

Through the pipes, a mixture of water and antifreeze is circulated which absorbs the heat and takes it to the heat pump, which heats it further before distributing hot water around the heating system.

Alternative renewable heating systems
As well as the various types of heat pump, there are many other renewable heating system options:

  • Biomass boiler: Rather than burning fossil fuels like gas or oil, biomass boiler burn plants or plant-based organisms such as wood logs, chips or pellets.
  • Solar thermal: Similar to a solar PV system, solar thermal captures solar energy to heat hot water that can be circulated to taps or the central heating system.
  • Hybrid heating system: Rather than removing a gas or oil boiler completely, putting a renewable heating system in its place, it's possible to combine the two with the system switching depending on which is capable of delivering the most efficient solution at the time.
  • Air, ground or water source heat pump?

    In the UK, very few homes are positioned close enough to a lake or river to make the installation of a water source heat pump possible. Fortunately, air and ground source heat pumps are perfect alternatives to help make properties more efficient and reduce energy bills.

    This means there's a heat pump option for just about any type of home and using Boiler Guide you can get free installation quotes from fully-qualified installers in your local area.

    Get FREE Heat Pump Quotes


    Get FREE Heat Pump quotes from trusted engineers in your area.Get quotes now.



About the author


Adam is our resident home heating expert. His experience and advice has helped millions of customers improve the efficiency of their homes and save money.

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