Water source heat pumps are a very good idea if you have access to a body of water. Not everyone has access to a large pond, loch or river, but for those who do, the higher specific heat capacity of water allows for much better heat transfer to your system than, say an air system.
The video below gives a great summary of the “river house” system installed as part of a home renovation project by Richard and Emma Meaden, which should give you a good overview.
Water source heat pumps are designed to efficiently transport heat from a water source into your household. A lake, pond, stream or river can be propelled through a heat pump and deliver exceptional results. This is particularly true if the temperature of the water is somewhere between 5 and 8 degrees Celsius.
These heat pumps operate similarly to ground source and air source heat pumps. However, rather than using the heat in the ground or in the air, a water source heat pump uses the reasonably consistent temperatures in its water source.
How They Work and How They Can Be Used
Flexible pipework is submerged in a stream, river, pond or lake and working fluid is pushed through the piping network. As the fluid flows, it soaks up heat from the surrounding water. An electric compressor then compresses the working fluid to raise the temperature. The heat can then be removed entirely from the working fluid via a heat exchanger. This provides hot water that can be used for under floor heating and other types of space heating.
Additionally, it can be channelled into the hot water system. A small quantity of additional heat will be required to get the water to a temperature where it can be used for baths and showers; this can be supplied by a boiler. When the heat is extracted from the working fluid, it is pumped back through the pipework and this completes a continuous cycle.
The hot water supply is pretty much constant. In spite of it being cooler during the winter, there should still be an adequate amount of heat to enable the pump to function. However, if the water source freezes completely, there will be an issue.
• The majority of the energy used for cooling, heating or hot water is pumped directly from the water.
• In contrast to ground source heat pumps, no trench or bore hole is necessary. All the pipework is submerged in the water source. This should have very little impact on your land space and visual appeal of the property.
• It is relatively simple to install the pipework. All that is required is situating the pipework within the water source.
• In comparison to traditional heating methods, water source heat pumps do not emit toxic or harmful fumes. This could considerably reduce your carbon footprint on the planet.
• Water source heat pumps are reliant on a body of water being on or close to your property.
• A water source heat pump will save a significant amount of energy annually. However, in cold climates, its net performance could drop during the winter.
Installation and Running Costs
The initial installing cost of water source heat pumps can be quite expensive, in comparison to other heat pump varieties. Its estimated cost is approximately £10k. However, thanks to government grants and savings, after a few years, homeowners will start to earn money.
There are basically 3 factors to consider when determining running costs of a water source heat pump:
• The pump’s efficiency
• The amount of heat required for the household
• The temperature of the water source
The efficiency of heat pumps differs among manufacturers but remain within certain boundaries. The COP of water source heat pumps could go up to 5; however, this value is rare. The COP value is usual between 3 and 4.3.
The actual efficiency of the heat pump can be calculated by the volume of work it has to do. This is based on the difference between the indoor and outdoor temperatures. The further apart the two temperatures are, the less work will be demanded of the heat pump to obtain the desired temperature.
Water Source Heat Pump Brands
One of the popular heat pump brands used in the UK is ThermSelect. This is an award-winning German brand, which switches automatically to the most efficient mode of operating, based on weather conditions. Modes can be used simultaneously or interchangeably. There is also an enhanced controllability on the device, which is handled by a control unit. This enables the separating of controllers for the geothermal circulation and the heat cycle.
• This is a flexible emission system that provides heat for under floor heating, water radiators and other heating circuits.
• It is capable of heating domestic hot water
• It is not totally carbon free as electricity is required to power the pump (this is the case for all brands of heat pump, though).
• The water distribution system flow rates are essential for its functionality
There is a growing need for the production and use of renewable energy solutions. As such, the UK government has been providing incentives to motivate commercial and residential property owners to increase their use of renewable energy. Using a water source heat pump will normally significantly reduce CO2 emissions.