How does a geothermal heat pump work?
- Glycol* is pumped through the exchange system, which consists of a series of pipes buried in the ground, at a temperature below the ground temperature. This temperature difference causes a transfer of heat energy from the ground to the glycol.
- In the heat pump evaporator, the glycol gives up the energy transferred from the ground to the refrigerant flowing through the refrigerator circuit, heating and boiling it.
- The refrigerant, now in vapour form is sucked by the compressor, considerably increasing its pressure and therefore its temperature.
- Then, this refrigerant, at high pressure and temperature goes to the condenser, where it cools and condenses giving up its heat to the water delivery system, which is heated.
- The hot water is circulated through the radiator system (floor heating, fan-coils, etc.), thus heating the home.
- Finally, the condensed refrigerant enters the expansion valve, which lowers its temperature and pressure in the evaporator so that it can again absorb heat captured by the glycol, thereby initiating a new cycle.
In short, the geothermal heat pump manages to extract and transfer heat from the ground into our home.
Three different ways of extracting heat from the ground
This consists of one or more vertical holes of depths between 80 and 150 meters into which the exchangers are introduced.
Installation is a simple and inexpensive, widely used, as it requires very little ground space and efficiency is very high.
The exchanger, arranged horizontally, is buried at a depth that may vary between 1.2 and 2 metres. Installation is simple, but requires a greater amount of land than vertical systems.
This type of extraction can be an option to consider when there is a well, spring or groundwater source.
In this case, water is pumped to the heat pump, the water’s energy is transferred, and it is then subsequently returned to the ground through an injection well.