The theory behind

A geothermal heat pump is not much different in logic from a regular heat pump. Their difference lies only in the medium they use to transfer heat to and from. While a conventional heat pump transfers heat to and from the external air, the geothermal heat pump transfers heat to and from the ground (or underground water). As a result, for the same building, a geothermal heat pump consumes even less energy to operate than a normal heat pump. It can go down to only 1/4 or 1/5 of the energy required by even the most modern burner / boiler system.

How do you exchange heat with the ground ?
The soil a few meters beneath our feet, like the air, is a huge energy store. It absorbs 50% of the solar energy and it remains in a nearly constant temperature during winter and summer. Placing a water pipe network – called geothermal exchanger - in the ground, we can use this free energy stored in the earth. In winter, the geothermal exchanger absorbs the heat from the earth and carries through a suitable device, the geothermal pump into our room to warm us. In summer, the same system, simply reversed, absorbs heat from the air conditioned space in the building (thus cooling it), and transfer it back to the "storage" of the earth.

Why consider a geothermal system instead of a regular heat pump ?
Because the geothermal heat pump takes advantage of the more constant temperature of the ground compared to the air. For example, in the summer, the air can reach 30-40C, while at the same time the ground (or underground water) is no more than 18-20C. In the winter, the ground temperature never drops below 15C, while the outside air can go below zero. The constant temperature gives an edge to the geothermal heat pump performance wise. While the regular heat pump has an efficiency factor (COP) of around 3, the geothermal can reach up to 5. It makes thus sense in larger houses / buildings and even more in locations where extreme weather conditions are experienced more often (ex. mountainous areas).

The Geothermal energy can be applied to new buildings of any size and use with the same benefits : in houses, villas, tourist residences, hotels, greenhouses, office buildings, wherever they are located.

Parts of a geothermal system
The parts of a geothermal installation are presented in the following image. The geothermal heat pump, in contrast to the regular heat pump, can be also placed indoors. In the living areas, it is combined perfectly with the underfloor piping systems, hidden air ducts, fan coils, etc.

  Parts of the system:
  A. Geothermal heat pump Climaveneta
  B. Geothermal exchanger (ex. below the        garden)
  C1. Fan coil
  C2. Underfloor systems
  D. Hot water

Geothermal exchanger types
The geothermal exchanger (tubing) inside the ground which receives / rejects heat from and to the ground, is made of common plastic polyethylene pipes (HDPE) with a life cycle of over 50 years. Their placement may be horizontal or vertical, as shown in the following figures. In cases where there are underground or surface waters near the building, they may also be utilized. The alternatives are present below :

Types of geothermal exchanger


Closed circuit with horizontal loops

It is the most common and simplest type. It is the first choice in buildings that have enough garden space available. The tube is placed in parallel "loops" at about 2 meters depth. A surface of garden about 3 times the floor area of the house is needed.
Closed circuit with vertical loops

This type is used in cases where the free space around of the building is not enough. The tube is positioned vertically, with a hole similar to the borehole and a depth from 45 to 100 m.
Open circuit with two wells
Such an arrangement continuously draws water from an underground aquifer body and then, returns the water to it. One well is used to draw water and a second one to return it. This type is used for buildings in proximity to a sea body, where we can find water with very swallow digging and water aquifer level is high (perfect for beachside hotels and villas). It offers high efficiency and reduced cost.
Closed circuit loops in a lake or sea

This solution can be used if a lake or sea, with depth of at least 2.5 meters is near the building. It also offers high efficiency.

Attention : One needs to be very careful when selecting a Company to design and implement a geothermal system, because it is a highly specialized task. Experience and confidence is essential. It is easy for a Company like Delta Techniki and Climaveneta but very difficult for inexperienced engineers.

For more information (also in English), please call us at tel. 210 94 00 720

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