Water Source Heat Pumps: Everything You Need to Know

In this guide, we’ll explore water source heat pumps (WSHPs)—how they work, their benefits, and key factors to consider before installation.  

What Is a Water Source Heat Pump?  

A water source heat pump (WSHP) captures heat energy from water to provide efficient heating and cooling for buildings. Unlike traditional heating systems that depend on fossil fuels, WSHPs utilize a renewable energy source, making them a more environmentally friendly option.  

Unlike air source heat pumps (ASHPs) that extract heat from the air, WSHPs draw heat from water bodies such as lakes, rivers, or streams.

Types of Water Source Heat Pumps  

Water source heat pump (WSHP) systems come in two main designs:  

Closed-Loop Systems  

These systems use a network of pipes submerged in natural water bodies such as lakes, rivers, or streams to extract heat. The pipes are filled with an anti-freeze solution, typically a water-glycol mixture, to prevent freezing in cold temperatures. The absorbed heat is transferred to a circulating fluid within the system, which is then delivered to the WSHP unit for compression and thermal energy release.  

Open-Loop Systems  

Instead of using a heat-transfer fluid, open-loop systems draw water directly from a borehole. The extracted water is brought to the surface, where it transfers heat energy before being discharged. Since this system lacks anti-freeze protection, there is a potential risk of freezing in colder conditions.

Advantages of Water Source Heat Pumps  

Energy Efficiency  

Water source heat pumps (WSHPs) are highly efficient, with a Coefficient of Performance (COP) typically around 5. This means that for every unit of electricity consumed, the system produces approximately five units of heat energy. This high efficiency translates into significant energy savings, reducing overall heating costs.  

Versatility  

WSHPs are suitable for both residential and commercial applications, providing heating and hot water for single-family homes, apartment complexes, offices, schools, and more. They can also integrate seamlessly with other heating systems, such as underfloor heating, enhancing flexibility in different environments.  

Environmental Benefits  

Compared to traditional heating systems that rely on gas, oil, or electric resistance heating, WSHPs produce significantly lower carbon emissions. By harnessing renewable heat from water sources, they help reduce the carbon footprint of homes and businesses, contributing to a more sustainable future.  

Long Lifespan  

WSHPs typically last between 15 and 25 years, but with proper maintenance, some systems can operate for up to 50 years. While the initial installation cost may be high, the long lifespan and energy savings help offset the investment over time, making WSHPs a cost-effective heating solution.

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 Applicability  

WSHPs require access to a suitable water source, which may not be available in all locations. This restricts their installation to areas with water bodies that meet the necessary criteria. Additionally, depending on local regulations, an abstraction license may be required to ensure compliance with environmental and safety standards.  

Maintenance Requirements  

Regular maintenance is essential to keep WSHPs operating efficiently. This includes inspecting components, cleaning filters and coils, and monitoring fluid levels. Neglecting maintenance can lead to reduced performance, higher energy consumption, and potential system failures.  

Slow Return on Investment  

The high initial installation cost of WSHPs means that it may take years to recoup the investment through energy savings. This can be a concern for individuals or businesses with limited budgets or those seeking a quicker financial return.  

Noise and Vibration  

Older WSHP models, in particular, may produce noticeable noise and vibrations, which can be a drawback for residential and commercial settings. Proper insulation, soundproofing, or newer, quieter models may be necessary to mitigate these issues.

Key Considerations Before Installing a Water Source Heat Pump  

Water Source Availability  

Before installing a WSHP, ensure there is a sufficient and reliable water source nearby, such as a lake, river, or stream. Assess the volume and consistency of the water supply to determine if it can meet your property's heating and cooling needs.  

Installation and Space Requirements  

WSHP installation can be complex, often involving excavation, piping, and other construction work. Evaluate the available space and consider potential challenges, such as land restrictions or difficult terrain, that may affect the installation process.  

Permits and Regulations  

Check local regulations and permit requirements before installation. Some areas have specific environmental or zoning restrictions that may affect where and how a WSHP can be installed. Obtaining the necessary approvals in advance can help avoid legal complications.  

Initial Cost  

Water source heat pumps typically have higher upfront costs compared to conventional heating systems. Expenses include equipment, excavation, and piping installation. However, the system’s long-term energy efficiency and durability can offset these initial costs, making it a worthwhile investment over time.  

Maintenance and Servicing  

Regular maintenance is essential to ensure the system operates efficiently and lasts as long as possible. Routine servicing may involve cleaning or replacing filters, checking refrigerant levels, and inspecting system components. Factoring in these ongoing maintenance costs is important when evaluating the overall feasibility of a WSHP.

Cost of Running a Water Source Heat Pump  

The operating costs of water-source heat pumps are generally higher than those of ground-source or air-source models. Around 50% of these costs are attributed to additional development work, including drilling, construction, and installation.  

However, despite the higher initial expenses, water-source heat pumps offer significant savings in running costs due to their high efficiency. The higher upfront investment is often recouped in a relatively short time through these long-term energy savings.