What is a ground source heat pump?

A ground source heat pump is a renewable heating system. The ground source heat pump extracts low-temperature solar energy stored in the ground or water using buried pipework and compresses this energy into a higher temperature. A ground source heat pump provides a building with 100% of its heating and hot water all year round.

How does a ground source heat pump work?

Heat naturally flows from warmer to cooler places. A ground source heat pump exploits these physics by circulating a cold fluid through ground array pipework in the ground or water. It absorbs low-grade surrounding energy from external heat sources, such as rock, soil, lakes and streams.

The ground source heat pump then compresses and condenses this free energy to a higher temperature and transfers it to the property’s heating and hot water system.

Having surrendered the absorbed energy from the ground to the heat pump, the fluid continues its circuit back to the submerged pipework to commence the cycle all over again.

The process of how a heat pump works.

  1. 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 the array is constantly warmed by the ground’s low-grade heat.
  2. Having increased in temperature, the anti-freeze mixture is fed into a heat exchanger called the evaporator.
  3. Within the secondary sealed side of the evaporator heat exchanger is a refrigerant that 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.
  4. 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.
  5. The hot refrigerant gas then flows into a second heat exchanger, called the condenser, which features an identical set of heat transfer plates.
  6. The condenser delivers water hot enough to serve the space heating system and the property’s hot water needs. Having transferred its heat, the refrigerant gas reverts to a liquid.
  7. 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.