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What Is A Water Source Heat Pump & How Does It Work?

Water source heat pumps (WSHPs) are part of the wider heat pump family of home heating technologies, alongside ground source and air source heat pumps. Despite being a relatively new method of sustainable heating available to the public, heat pumps as a technology have a long and storied history, with the first heat pump being designed in 1855. Water source heat pumps operate by extracting thermal energy (heat) from a water source near your property and converting collected energy into heating and hot water for your home. As you are required to have a body of water near your property, water source heat pump systems are ideal for homeowners that have a suitable source onsite, such as a lake, river, stream or borehole.

How does a water source heat pump work?

The system will be installed into a specified water source - the size of the installation is determined by a professional installer, based on the size of the property to be heated and the volume of the water source itself.

A series of submerged pipes placed underground facilitate the heating process; by using an antifreeze liquid in closed-loop systems or the water from the source itself in open-loop systems, heat energy can be effectively transferred to the heat pump itself. Once the heat energy has been brought into the system, the overall process remains much the same as other heat pump methods.

How much does a water source heat pump cost?

While the overall price of having a heat pump installed into your home will vary between installers, there are some general guidelines as to the total cost. Typically, the total cost of installing a water source heat pump into your home will reach approximately £10,000. While this seems rather high, it’s important to understand the cost-saving benefits on offer from having a WHSP installed on your property.

On average, homes with a water source heat pump compared to a traditional heating method stand to save around 15% on their heating bills annually. Better yet, with proper use, maintenance and servicing, a water source heat pump will last anywhere from 15 to 50 years. This extends much further than a traditional combi-boiler, which are usually recommended for replacement at around the 10 year mark.

There are grants and incentives on offer for homeowners who look to make the switch through the Domestic Renewable Heat Incentive scheme, though we recommend reviewing government guidance before making a decision.

Types of water source heat pumps

Water source heat pumps can come in two configurations: closed loop and open loop. Closed loop systems are the more common of the two, though both have their use in various property layouts.

Closed loop system

A closed loop water source heat pump is ideal for properties with a sufficient body of water close to the property, where the necessary piping can be routed underground and into the water. Closed loops are generally a cheaper option to open loops, as they are simpler to install and don’t require the same specific conditions for installation.

Open loop system

Open loops require additional regulations to be installed and used, as the system actively pulls water into the system for operation. The water needs to be clean and sufficient for the system to draw and filter water to and from the main water source.

Are water source heat pumps reliable and efficient?

While the overall efficiency will change as the temperature of the water source lowers and rises over time, the actual efficiency often outperforms both air and ground source heat pumps. This is due to the consistency in water temperatures outside, regardless of the weather conditions you live in - most water sources in the United Kingdom will sit somewhere between 7°C and 12°C.

Keep in mind that if your water source is prone to frost and freezing over, the overall performance of your WSHP could be affected. This will be assessed by your installer during the inspection and specification stage.

As an added benefit, pipework systems are installed to be submerged underwater, making water source heat pump systems a viable option for projects that are especially aesthetically sensitive and require minimal visual impact, both during installation and once completed.

Water source heat pumps are designed to work in cold temperatures and are incredibly efficient. They do require electricity to operate, but 75% of the energy required is generated from the thermal energy extracted from a water source, with only 25% being required from electricity. This means that 75% of the energy you use will be from a renewable source, which will reduce your emissions and CO2 impact.

Advantages and disadvantages of water source heat pumps

Although water source heat pumps are an important part of a sustainable future, there are advantages and disadvantages to using a WSHP at your property.

The advantages of using thermal energy from water:

  • Provides heating and hot water for your home
  • Perfect for properties located near a water source
  • Heat pumps can be housed indoors or inside outbuildings where required
  • Doesn’t require extensive digging or drilling for installation
  • Ideal for properties generating electricity from a hydropower
  • Quiet during operation
  • Minimal visual impact once installed
  • Works in cold outside temperatures
  • Compatible with radiators and underfloor heating
  • Minimal ongoing maintenance
  • No fuel deliveries or fuel stored onsite
  • Possible to benefit from Government incentives such as RHI payments

The disadvantages of using thermal energy from water:

  • Can be costly for initial installation and will take a number of years before paying back the investment
  • Only viable for properties with a sufficient body of water nearby
  • Open loop systems require special planning and permissions to allow installation
  • Installation is more difficult than other home heating solutions

Is a water source heat pump suitable for my property?

Here are a few things to consider when looking into a water source heat pump system for your property:

Do you have a suitable water source on your property? It’s important that a suitable water source can be accessed for the installation to be completed successfully. Rivers, streams, and lakes are all potential sources. Speak to a reputable installer who will be able to conduct a feasibility test and assess whether your local water source is suitable.

Is your home well insulated? Generating heating and hot water sustainably is only beneficial if you have improved the efficiency of your home. Each property is unique, but it is important to understand what other measures can be done to reduce heat being lost in your home. Looking at loft insulation and whether you have double glazing windows will be a good start, but consult a professional for further guidance on what is feasible for your home.

Are you looking to replace a heating system or, for new-build homes, is this the first heating system to be installed? Replacing an ageing heating system will deliver greater cost and efficiency benefits. However, for new-build homes, it is worth discussing with your installer how your heat pump system will work throughout your home – this includes choosing underfloor heating or radiators, as well as suitable controls to operate it.

Interested in having a water source heat pump installed in your home? View our range of water source heat pumps here. Alternatively, you can find a local Vaillant Advance renewables partner who will be able to give you a free no-obligation quote. They will survey your property and will be able to recommend the perfect Vaillant solution for your heating and hot water demands.

Learn about other types of heat pumps

Even if your property isn’t suitable for a water source heat pump, there are alternative solutions with the same technology. Both air source and ground source heat pumps are viable for the majority of homes in the United Kingdom and benefit from many of the same cost-saving and environmental advantages a water source heat pump provides. Learn more about the different heat pumps below.

Air source heat pumps

Ground source heat pumps