Water source heat pumps: Everything you need to know

In this guide, we will explore water source heat pumps. From understanding how they work and their benefits, to what considerations you should keep in mind before installing one.

What is a water source heat pump?

A water source heat pump (WSHP) harnesses the heat energy from the water to provide heating and cooling for properties. While traditional heating systems rely on fossil fuels, WSHPs utilise a renewable energy source, making them better for the planet.

And unlike air source heat pump, which extracts heat from the outside air, WSHPs draw heat from water bodies, such as rivers or streams.

Types of water source heat pumps

There are two main designs for WSHP systems:

Closed loop systems

Utilises a network of pipes submerged in lakes, rivers, or streams to extract heat from the water. These pipes are filled with an anti-freeze fluid, often a mixture of water and glycol, which helps prevent freezing during cold weather.

The heat extracted is then transferred to a fluid circulating within the pipes and taken to the WSHP unit. It then undergoes compression, releasing thermal energy.

Open loop systems

Instead of relying on a fluid to carry the heat, the system uses water from a borehole. Water is lifted to the surface, where it extracts heat energy. This method poses a potential risk of freezing since there is no anti-freeze present in the system.

Water source heat pumps pros

Energy efficiency

Water source heat pumps are highly energy efficient, with COP (Coefficient of Performance) values typically ranging around 5.

So for every unit of electricity used to run the pump, 5 units of heat energy are produced. This high efficiency can cause significant cost savings on energy bills.

Versatility

Both residential and commercial buildings can benefit from water source heat pumps. They can be used for heating and hot water in single-family homes, multi-unit buildings, offices, schools, and more. They can also work with other types of heating systems, such as underfloor heating.

Environmental friendliness

WSHPs are considered eco-friendly as they generate less CO2 emissions than standard heating systems like gas, oil or electric. This makes them a great option for homes and businesses looking to reduce their carbon footprint.

Long lifespan

On average WSHPs last around 15-25 years. However, with proper maintenance they may be able to last for up to 50 years. Even with high installation costs you're likely to recoup your investment over time through energy savings and the longevity of the system.

Water source heat pumps cons

High upfront cost

Installations typically cost more than those for traditional heating systems. Drilling boreholes or installing pipes into the ground can make it a more expensive option than other heating systems.

Limited application

As WSHPs require access to a suitable water source, they may be impractical for use in some areas. This limits their use to areas with access to water sources that meet the necessary requirements for installation.

Depending on the installation, an abstraction license may be required to comply with environmental and safety standards.

Maintenance requirements

Water source heat pumps require regular maintenance to ensure optimal performance. This includes inspections, cleaning of filters and coils, and checking fluid levels. Failure to properly maintain the system can result in reduced efficiency and potential breakdowns.

Slow return on investment

Due to the high upfront cost of installation, it may take a longer time to recoup the initial investment through energy savings. This can be an obstacle for individuals or businesses with limited budgets or those looking for a quick return.

Noise and vibration

Older models, especially, can generate noise, which can be a drawback for some homeowners or businesses. Proper insulation and soundproofing measures may be required to minimise the impact of these factors.

Considerations before installing a water source heat pump

Water source availability

Before installing a WSHP, you need to ensure that there is an adequate body of water nearby, such as a lake, river or stream. Assess the quantity of water available to determine if it can meet the requirements of your property.

Installation and space requirements

Installing a WSHP can be complex and may require excavation, piping, and other construction work. Assess the available space and consider any potential challenges or restrictions before installation.

Permits and regulations

Check local permits and regulations regarding the installation of water source heat pumps. Some areas may have specific requirements or restrictions that need to be followed.

Initial cost

Water source heat pumps can have a higher initial cost compared to other heating systems. The installation process, including excavation and piping, can add to the overall cost.

However, the long-term energy savings and lifespan of the system can beneficial in the grand scheme of things. Therefore, the over time, the energy savings can help offset the higher upfront expenses.

Maintenance and servicing

Systems require regular maintenance to ensure optimal performance and longevity. This may include cleaning or replacing filters, checking refrigerant levels, inspecting components, and more. It is important to factor in these ongoing maintenance costs when considering a water source heat pump.

How much does it cost to run a water source heat pump?

Water-source heat pumps are typically higher than those of ground-source and air-source models. Approximately half of these costs are attributed to additional development works such as drillings, construction, and installation.

Despite initial expenses, expect savings on running costs due to the high efficiency of water-source heat pumps. In fact, the higher upfront investment often pays off in a relatively short period of time thanks to these long-term savings.

Are there any schemes to help with costs?

The Boiler Upgrade Scheme aims to help residents in England and Wales install low carbon heating systems.

This includes both air source and water-source heat pumps. It can potentially provide up to £7,500 off the cost and installation of an air source heat pump.

Learn more about Air source heat pump grants.