Beyond Efficiency: navigating the benefits of Water-Source Heat Pump Systems

In the current context, where the pursuit of efficiency and sustainability are becoming the norm, the water-source heat pump system stands out. 

This heightened emphasis on environmental responsibility and energy efficiency aligns with the water-source heat pump working principle. From facilitating renewable energy integration to its increased energy efficiency, this system is clearing the way for major decarbonization efforts in areas such as industrial heating and district heating initiatives.

But what is the water-source heat pump working principle exactly and what are its benefits both in economic terms and within the global shift towards cleaner and greener energy solutions? Keep reading to find out.

What is a water-source heat pump system

A water-source heat pump system is a type of heat pump that uses water as a heat exchange medium to provide heating and cooling for buildings. 

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As such, the system is able to extract heat from a water source (such as sewage water, lake, or a river) to provide both heating and cooling for indoor spaces.

The system is made of the following components:

  • Heat pump unit: main component, responsible for extracting heat from a water source and then transferring it for heating or cooling. This is achieved through its cycle, which consists of the refrigerant, the compressor, the condenser, the expansion valves, and the evaporator.
  • Water loop, in charge of circulating water between the heat pump and the water source, so that it absorbs or releases heat during the heat exchange process.
  • Distribution system, such as air ducts or radiant floor heating, which uses heat or cold provided by the heat pump.

Closed or open loop system: key differences

The water-source heat pump working principle involves the transfer of heat between a water source and a building. Roughly speaking, there are two types of water-source heat pump system, which also present different working principles:

Closed-loop water-source heat pump

This configuration implies water and an antifreeze solution, circulating through a closed loop of pipes buried in the ground or submerged in a water source. This provides great control over the fluid, and greater system stability.

In operation, heat is extracted from the water source thanks to this circulating solution. Then, the refrigerant releases the absorbed heat to the building's interior thanks to the condenser coil, providing space heating.

Open-loop water-source heat pumps

The open-loop system means water is directly drawn from a natural water source, which can result in higher efficiencies when extracting heat. This heat is then passed through a heat exchanger where heat is extracted. The heat can now be transferred to the refrigerant, which then evaporates in the evaporator coil. Finally, heat is distributed to the building’s interior. 

Comparing a water-source heat pump system to air-based heat pumps

The benefits associated with a water-source heat pump system are directly related to the properties of water. This fluid possesses a remarkable capacity to retain heat in relation to its volume, surpassing that of air. As such, it presents a high heat capacity and efficient heat transfer characteristics, with a rapid absorption and release of heat.

One key advantage in this type of system is that this thermal capacity and inertia allow water to retain solar heat acquired during the summer, carrying it through to the winter months. That means that river water and aquifers maintain higher temperatures than air even in colder seasons.


Benefits of a water-source heat pump system

Excellent energy efficiency

The water-source heat pump system working principle enables high energy efficiency compared to traditional heating and cooling systems. This is directly related to the high thermal capacities and stable water temperatures described above. 

As such, COP values for large water-based industrial heat pumps can range from 3 to 6 or higher, meaning they provide from 3 to 6 units more heating or cooling output per unit of electric energy input. 


Their ability to provide both heating and cooling is particularly advantageous. But that’s not all: a water-based heat pump system can be designed to utilize various heat exchange methods, including direct exchange with water or through the use of intermediate heat exchange fluids. This allows for great customization possibilities, and thus increased abilities to adjust to a project’s specific requirements.


A water-based heat pump system is not as dependent on outdoor air conditions as other air-based alternatives. While we’ve already seen that this brings great advantages in terms of efficiency,  this enhanced independence also allows for more stable and reliable performance, especially in extreme weather conditions.


By employing a water source as a heat exchange medium, this type of heat pump moves away from systems that rely solely on the electrical grid or fossil fuels. This increases the efficiency of the system and its ability to harness renewable energy sources, which helps to reduce greenhouse gas emissions.

Balancing energy supply

Because heat is easily storable in the form of hot water, water-source heat pumps can play a key role in generating models for heating and cooling that provide balance in demand.

In fact, heat pumps can assume a substantial role in interseasonal heat transfer systems,  facilitating the transfer of energy from summer to winter and contributing to a year-round, environmentally-conscious energy strategy.  

Reduced operating costs

The water-source heat pump working principle results in lower operating costs in the long term thanks to its outstanding efficiency, which reduces utility bills. 

At the same time, their long service life and low maintenance requirements also correspond to lower costs. This type of heat pump presents fewer moving parts and less wear and tear, so that they require lower maintenance, and contribute to its overall cost-effectiveness.


Modular designs and scalability can be applied to a water-source heat pump system,  allowing it to be easily expanded or modified on changing needs. This potential also means that customization and adaptability to different projects are also possible.

At ARANER, we’re at the forefront of efficient, cutting-edge thermal engineering, which means water-source heat pumps are part of our portfolio within the industrial heat pump solutions.

Always ready to adjust our designs and implementations to the needs of each project, we’re prepared to integrate the most efficient and sustainable heat pump to your project. This includes state-of-the-art district heating initiatives that integrate water-source heat pumps with thermal energy storage (TES).

Would you like to learn more about the water-source heat pump working principle and how we can help you achieve a cost-efficient, sustainable structure? Get in touch with us and speak to our team.

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