The Technology

How Ground Source Heat Pumps Work

Watch our video: 'How a Ground Source Heat Pump Works'

What is a heat pump? How does it work? These are very common questions, and answered very simply in this short 3 minute video, brought to you from Kensa Heat Pumps.

For a more technical explanation, look at our extended cut here, with additional commentary from our Technical Director, and co-founder, Guy Cashmore.

With over 230,000 total views on YouTube so far, our ‘How a ground source heat pump works’ videos are an internet hit!

Watch here

Nature's underfloor heating

A ground source heat pump (GSHP) extracts solar energy stored in the ground, water courses, and converts this to a higher temperature for use in a buildings heating distribution system.

Ground source heat pumps are extremely energy efficient, with every unit of electricity used (to drive the pump and compressor), producing between 3 and 4 units of heat. This means heating costs are effectively quartered.

Due to their high efficiencies, CO2 emissions are significantly lower than traditional fossil fuelled systems (up to 43% lower than gas).

Watch Kensa's video 'How a ground source heat pump works'

Cut energy bills by a quarter

For each kilowatt consumed by the heat pump, 4 kilowatts of energy is generated.

1kW of electricity = 4kW of heat

Effectively meaning the cost per kilowatt hour is quartered.

This is known and the coefficient of performance (COP).

Read more about COP

Improving efficiencies

The lower the flow temperature required in your heating distribution system, the less work your ground source heat pump will need to make, therefore making it even more efficient, and possibly even reducing the size and cost of pump required.

To achieve as low flow temperatures as possible, insulation is the first place to look.

better insulation = lower flow temperature = less work & more efficient heat pump

Read more

The science bit

  • A cold water anti-freeze mix is pumped through the ground within a series of energy absorbing pipes, known as ground arrays. As heat naturally flows from warmer to cooler places, the anti-freeze mix circulating around the array is constantly warmed by the ground’s low grade heat.
  • Having increased in temperature, the anti-freeze mixture is fed into a heat exchanger called the evaporator.
  • Within the secondary sealed side of the evaporator heat exchanger is a refrigerant which acts as a heat transfer fluid. When the water anti-freeze mixture enters the evaporator, the energy absorbed from the ground is transferred into the refrigerant which begins to boil and turn into a gas. The refrigerant never physically mixes with the water anti-freeze mixture. They are separated like sandwich layers by the plates of the heat exchanger which permit the heat transfer.
  • This gas is then fed into a compressor. The pressure of the refrigerant gas is increased in the compressor, which makes the gas temperature rise. The hot refrigerant gas then flows into a second heat exchanger, called the condenser, which features an identical set of heat transfer plates.
  • The condenser delivers water hot enough to serve the space heating system and, if required, the property’s hot water needs.  Having transferred its heat, the refrigerant gas reverts to a liquid.
  • This liquid is then passed through an expansion valve at the end of the cycle to reduce its pressure and temperature, ready to commence the cycle all over again.
Watch Kensa's video 'How a ground source heat pump works'
I think ground source is the future of energy generation and everyone should embrace this this technology."

Alistair Mackintosh, Selfbuilder

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