Water Source Heat Pumps

Transferring thermal energy from lakes, rivers and ponds to provide indoor heating and hot water.



What is a water source heat pump?


Water source heat pumps are powered by electricity and are used to transfer thermal energy from bodies of water such as lakes, rivers, ponds and waterwells, to provide heating, cooling and hot water inside a property. This form of clean, renewable energy can be used for residential and commercial buildings which are located near to a water source (normally within 100 metres). Water source heat pumps can be more cost effective to install than ground source heat pumps as less ground work is required, they also achieve efficiencies as high as 400% which will significantly reduce your energy bills.


MasterTherm Water Source Heat Pump
Modern House by Lake


How does a water source heat pump work?

Water source heat pumps are installed indoors and powered by electricity making them clean and combustion free. The heat pump is connected to a series of pipes called lake collectors or pond mats which are floated out onto the water surface where they sink and are held in place by weights. The collectors circulate a fluid which absorbs the thermal energy from the water. The fluid is then passed through a compressor which increases the temperature to a usable level before reaching a heat exchanger that transfers the heat to the distribution system including radiators, underfloor heating and hot water cylinders. 

MasterTherm heat pumps offer an intelligent automated heating system and integration with time of use electricity tariffs. All you need to do is set your preferred temperature once and your MasterTherm system will automatically optimise toward delivering your preferences as efficiently as possible whilst taking into account weather forecasts and the price of electricity to provide maximum comfort and additional savings of up to 35% on your energy bill - on top of the already low cost of running a heat pump.

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The Benefits of a Water Source Heat Pump


  •  A more environmentally-friendly heating system with excellent efficiency
  • Highly sustainable
  • More cost-effective to install than a ground source heat pump due to less ground work
  •  Reduces your monthly energy bill
  •  Clean and combustion free
  •  Specially insulated for quiet operation
  • Functionality to also provide passive and active cooling
  •  Suitable for buildings of all sizes from residential to commercial
  •  Works with a variety of heat distribution systems including underfloor heating, radiators and fan coil units
  •  Requires minimal maintenance and has a long lifespan of around 25 years
  •  No need for fuel cards or fuel deliveries
  •  Receive government financial benefits such as the Renewable Heat Incentive


MasterTherm Ground Source Heat Pump - Silver
AquaMaster Inverter Water Source Heat Pump



Our AquaMaster Inverter Ground Source Heat Pump


With its robust design and outstanding efficiencies, our AquaMaster Inverter offers state of the art performance levels which can be applied to use in residential and commercial buildings of any size or design. Equipped with weather compensation, solar thermal integration and the ability to offer simultaneous heating and cooling, it uses intelligent zone control and automatic optimisation to deliver year-round comfort. Available for both ground source and water source projects.

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FAQs About Water Source Heat Pumps

What is the efficiency of a water source heat pumps
MasterTherm ground source heat pumps boast market leading SCOP’s (seasonal coefficient of performance) ratings. A prime example is our AquaMaster Inverter 26i 3-9kW Inverter ground source heat pump with a SCOP of 4,83. A well-performing heat pump will produce around 3-4kWh of heat for every 1KW or electricity used, this is an efficiency of 300-400% compared to a new gas boiler which has an efficiency of 90%.
What are the space requirements?
For residential properties, heat pumps are usually installed in utility rooms, airing cupboards, garages or outbuildings. The water source needs to be deep enough so that it doesn't freeze in winter and if it's used for other purposes such as boating, care needs to be taken than there is sufficient room to avoid the collectors so that they are not damaged. The size of the water source required depends on the size of the property and its required heat load (higher heat load could require more/longer pond mats/lake collectors so the water source will need to be bigger to accommodate this.
Will the heat pump heat the house in freezing weather?
Yes. Water source heat pumps deliver heat all year round, even in freezing conditions. As a back-up (in the unlikely event of system breakdown), we are able to fit our ground and water source heat pumps with an immersion heater.
Can water source heat pumps cool?
Yes, water source heat pumps can provide natural (passive cooling) or active cooling which is more in-line with traditional air conditioning. Using a heat pump for cooling often space, time and money as you won't need to install two separate systems.
How do you size a water source heat pump?
It's important to correctly size a water source heat pump, if it's output is too low you may not reach your preferred temperatures and if it's too high your system becomes less efficient which means you won't achieve the energy savings your property has the potential for. To correctly size a heat pump, heat loss and heat load reports should be carried out and the system designed with appropriate hot water storage and heat distribution such as underfloor heating or radiators. Generally a well insulated house requires 1 kilowatt of heat for every 25m2 which requires heating.
Can water source heat pumps work with radiators?
Yes water source heat pumps can work with radiators, however the radiators should be correctly sized for the system. Ground source heat pumps can also work with fan coil units and underfloor heating.
How long does a water source heat pump last?
Water source heat pumps have a long lifespan, lasting around 25 years or more.
Is a heat pump easy to control and use?
Yes, MasterTherm heat pumps can be controlled online via your internet browser or via the MasterTherm smartphone app. Once you programme your preferred temperatures, the heat pump will automatically operate to deliver your preferences as efficiently as possible.
Do you need planning permission for a water source heat pump?
Generally for residential installations you won't require planning permission. However if you live in a conservation area or in a listed building you should check requirements with your local council authority.
What is the difference between open and closed loop water source heat pumps?
Closed loop systems circulate a fluid through the lake collectors and the system is closed so that no water from the lake can get inside the pipes. An open loop system has open lake collector pipes which circulate water directly from the lake, taking it in at one end and then outputting it from another into a different area of the lake. Open loop system can achieve slightly better efficiency however they are prone to blockages and require filtration.