Water source heat pumps explained 

What is a water source heat pump? 

A water source heat pump (WSHP) is a heating and cooling system that extracts heat from natural water sources, such as lakes, rivers, or wells, to efficiently warm your home (or other buildings).

It’s one of several different types of heat pumps, alongside ground source heat pumps which use heat from the earth, and air source heat pumps which use heat from the air outside.

What is the difference between a ground source heat pump and a water source heat pump?

The main difference between ground and water source heat pumps is where they extract heat from. Although both of these types of heat pumps have pipes that are submerged below ground level, ground source heat pumps extract heat from the earth and water source heat pumps extract heat from natural bodies of water.

How do water source heat pumps work? 

Water source heat pumps work by transferring the heat energy from a natural source of water using a closed or open loop system to provide heating for your home.

What water sources can be used with a water source heat pump?

Water source heat pumps can be used with a variety of different water sources such as:

• Rivers
• Canals
• Lakes
• Mines
• Sea
• Groundwater aquifers (although these are usually referred to as ground source heat pumps rather than water source)

Where does the water from a heat pump go?

In an open-loop system, the water is transported from its source to the heat pump and then transferred back to the source of water. In a closed-loop system, the water doesn’t leave the source.

Types of water source heat pumps 

There are two main types of water source heat pumps: closed-loop and open-loop systems.

Closed-loop water source heat pump systems

A closed-loop water source heat pump works by circulating a mixture of water and antifreeze through pipes or heat exchange panels that are submerged in a body of water. As this mixture travels through the pipes, it absorbs heat from the water and transfers it to the heat pump.

Open-loop water source heat pump systems 

In an open-loop water source heat pump, water is pumped directly from the natural water source and sent straight to the heat pump. Heat is then extracted from the water while in the heat pump and the water is then pumped back to its source.

Water source heat pump pros and cons 

Water source heat pumps won’t be suited to everyone so let’s take a closer look at the pros and cons.

Pros of water source heat pumps 

Water source heat pumps offer a range of impressive benefits such as:

• Lower carbon emissions: By using renewable water sources for heat, these systems significantly reduce carbon dioxide emissions compared to traditional heating systems.
• Energy efficiency: Water source heat pumps are highly efficient and use less energy to provide heating than traditional heating systems.
• Cost-effective: The high efficiency of these systems leads to lower running costs over time, helping reduce energy bills.
• Low maintenance: With fewer moving parts than traditional heating systems, water source heat pumps generally require less maintenance, saving time and money on upkeep.
• Quiet operation: As the pipes are submerged in water, these systems operate quietly.
• Longevity: Water source heat pumps tend to have a longer lifespan, often lasting 15-25 years, making them a durable investment.
• More environmentally friendly than traditional heating systems: By relying on natural water sources and producing fewer emissions, these systems are a more environmentally friendly option than traditional heating systems like gas boilers.
• Consistent performance: Since water temperatures remain relatively stable, these systems perform reliably throughout the year.

Cons of water source heat pumps 

While water source heat pumps offer many benefits, they do come with some downsides that are important to consider:

• High upfront costs: Initial installation costs of water source heat pumps are often significant, covering equipment, excavation, and any custom work required to access a water source.
• Installation challenges: Installing a water source heat pump can be complex, particularly if the water source is hard to access or requires special permits, adding to the time and cost.
• Higher electricity usage: Although more efficient than traditional systems, water source heat pumps still rely on electricity to run pumps and compressors which could lead to higher electricity bills, especially if not paired with renewable energy.
• Requires proximity to a water source: A sustainable, accessible water source is essential for these systems. Not all locations have nearby rivers, ponds, lakes, or wells, making this a limiting factor for some properties.
• Potential environmental regulations: In some regions, strict regulations govern the use of natural water sources which may require additional permissions or adherence to environmental standards.
• Space requirements: Closed-loop systems in particular need space to install piping networks underground or underwater, which may be challenging on smaller properties.
• Vulnerability to water source changes: Changes in the water source such as temperature shifts, reduced water levels, or seasonal drying, can impact the efficiency of the system or render it unusable.
• Water quality concerns: If using untreated water (like from lakes or rivers), sediment and mineral build-up can affect system performance in open loop systems, and require periodic cleaning or filtration.

Common questions about water source heat pumps 

How efficient is a water source heat pump? 

Water source heat pumps are a much more efficient way to heat your home than traditional heating systems like boilers. Water also remains warmer than air on the coldest days, making it a more efficient option than air source heat pumps.

How much does water source heat pump installation cost? 

According to the Eco Experts, water source heat pumps cost from £6,000 to £11,000 on average to buy and install.

What are the requirements for a water source heat pump? 

Installing a water source heat pump can be complex and it won’t be suitable for everyone’s home. To install a water source heat pump you must have:

• A nearby water source with stable year-round temperatures
• Adequate water flow to meet heating demands, especially in open-loop systems
• Permits and environmental compliance as some areas may have specific requirements or restrictions
• Space for loop installation (closed-loop systems) in water or underground
• Good water quality to prevent clogs and maintain efficiency
• Sufficient electricity supply to power the system

How much water does a water source heat pump need? 

The amount of water you need for a water source heat pump will vary depending on how much heat your home needs and therefore the size of your home.

Looking to save more energy at home? 

Whether you’re looking to find out more about heat pumps or want to explore more ways to cut your energy usage at home, our energy saving advice hub has everything you need to take charge of your energy usage.