An Introduction to Water-Source Heat Pumps

Written by: Ian Nock | Engineering Manager |  Renewables First

Water-source heat pumps (WSHP) are energy efficient systems that will significantly reduce the carbon emissions associated with the heating and cooling of a building. In this article we will explore the purpose of heat pumps and consider some of the pros and cons of the different variants that are available.

Heat pumps are devices that transfer heat energy from one place to another, effectively providing both heating and cooling for a space. This technology is commonly used in domestic fridges, transferring the thermal energy to cool the inside of the fridge and dump it externally, heating the outside space. This same principle has been scaled up to heat and cool much larger spaces including houses and offices. In fact, anything that requires heating or cooling will be a good candidate for a heat pump.

The benefit of transferring thermal energy between locations rather than just using electricity to heat directly is the efficiency gain. Heat pumps can transfer between 2 and 7 kilowatt-hours of thermal energy for every kilowatt-hour of electrical energy consumed. Of course, you could use the electrical supply to directly heat the space, but this would only produce 1 kilowatt-hour of thermal energy for each kilowatt-hour of electricity consumed. The key to any heat pump system is how to obtain the highest running efficiencies for the site.

The key factor influencing the efficiency of a heat pump system is the temperature difference between the source temperature entering the heat pump and the distribution temperature exiting. The smaller this difference the more efficient the system.

The distribution temperature requirements will be the same whatever type of system is being installed. This is determined by the insulation levels of the building and the type of distribution system installed. The typical space heating distribution temperature range of heat pumps is 35 to 55 °C.

For the external thermal source supplying the heat pump there are two main sources common to most buildings, the air and the ground. The ground offers more stable temperatures year-round with the extreme highs and lows of air temperature removed, proving to be a good sink for heating during the winter and cooling during the summer. This results in a more efficient system, with lower running costs and larger carbon-emission savings. Ground-source systems also have the aesthetic advantage of not being visible from the outside of the building whilst air-source requires large external units. However, the big advantage of an air-source system is their ease of installation and therefore lower upfront costs.

Properties with access to a body of surface water such as a large pond, river or even the sea have a third option to source their thermal energy from. Water-source heat pumps (WSHP) have the advantage of stable temperatures, like ground-source, but given the improved thermal properties of water, require a smaller installation footprint. Their visual impact on the outside of the building is usually minimal and with no requirement for specialist installation equipment they can offer financial savings over ground source systems.

If you or your business are looking to reduce its carbon emissions and you think you could benefit from a water-source heat pump then let us know. Click on the button below and tell us about your project. Renewables First have been involved with the design and installations of many systems from residential to large office spaces. Find out more on our dedicated heat pump web pages.. If you can’t find what you are looking for then send us your question and we’ll get an answer to you.

Ian has been working in the renewables sector since 2014 and leads the Net-zero, Heat Pumps and Solar PV teams for Renewables First. He works closely with our engineering team to share practical, evidence-based renewable energy advice.

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