Geothermal heating is one of the most promising alternative sources of energy generation. Unlike solar systems, it practically does not depend on the season. But is it profitable to heat a house using the heat and energy of the earth?
Geothermal heating at home
First, you need to understand the principles of obtaining thermal energy. They are based on the temperature rise as you go deeper into the ground. At first glance, the increase in the degree of heating is negligible. But thanks to the advent of new technologies, heating a house using the heat of the earth has become a reality.
The main condition for organizing geothermal heating is a temperature of at least 6 ° C. This is typical for middle and deep layers of soil and water bodies. The latter are highly dependent on the external temperature indicator, therefore they are extremely rarely used. How is it practically possible to organize the heating of a house with the energy of the earth?
To do this, it is necessary to make 3 circuits filled with liquids with different technical characteristics:
- Outer... More often antifreeze circulates in it. Its heating to a temperature not lower than 6 ° С occurs due to the energy of the earth;
- Heat pump... Without it, heating from the energy of the earth is impossible. The heat carrier from the external circuit with the help of a heat exchanger transfers its energy to the refrigerant. Its evaporation temperature is less than 6 ° C. After that, it enters the compressor, where, after compression, the temperature rises to 70 ° C;
- Inner contour... A similar scheme is used to transfer heat from the compressed refrigerant to water in the overcoming system. Thus, heating from the bowels of the earth takes place at minimal cost.
Despite the obvious advantages, such systems are rare. This is due to the high costs for the purchase of equipment and the organization of the external circuit for the intake of heat.
It is best to entrust the calculation of heating from the heat of the earth to professionals. The efficiency of the entire system will depend on the correctness of the calculations.
How the heat pump works
The heart of geothermal heating is the heat pump. It consists of several components, the work of which directly affects the efficiency of the entire system. Therefore, before planning heating a private house from the ground, you need to find out the main characteristics of this unit.
Since this device belongs to the category of complex equipment, it is recommended to purchase only factory models. The heat pump design includes the following components:
- Evaporator... In this block, energy is transferred from the external circuit;
- Compressor... Required to create high pressure in the refrigerant environment;
- Capillary... It serves to reduce the internal pressure in the refrigerant circuit;
- Control system... With its help, the heating of a private house from the ground is regulated - the temperature regime of operation, the rate of passage of heat carriers, etc.
The main problem in the independent manufacture of a heat pump is to reduce heat losses and normalize the operation of the internal circuit with the refrigerant. The factory models are set up at the manufacturing stage, and the design provides for the possibility of adjusting its parameters.
How to correctly calculate the pump parameters so that the heat of the earth for heating the house provides a normal temperature? To do this, you need to know the heat output of the pump. For a rough calculation, you can use the following formula:
Q = (t1-t2) * V
Where t1-t2 - temperature difference on the inlet and return pipes, ° С,V - estimated volume of heat carrier consumption, m³ / h,Q - rated power of the heat pump, W.
This technique is inapplicable for complex systems, since there are many additional factors in them. In particular, heat losses on the mains. This is especially true for those areas where it comes out as close to the ground surface. To minimize heat losses, it is necessary to insulate the heating pipes in the ground.
Since the operation of the heat pump depends on electricity, it is recommended to install an emergency power supply unit.
Geothermal heating options
In order for the energy of the earth to be used to heat the house as much as possible, you need to choose the right external circuit diagram. In fact, any medium - underground, water or air - can be a source of heat energy. But at the same time, it is important to take into account seasonal changes in weather conditions, as mentioned above.
Currently, there are two types of systems that are effectively used to heat a house using the heat of the earth - horizontal and vertical. The key selection factor is the area of the land plot. The layout of the pipes for heating the house with the energy of the earth depends on this.
In addition to it, the following factors are taken into account:
- Soil composition... In rocky and loamy areas, it is difficult to make vertical shafts for laying highways;
- Soil freezing level... He will determine the optimal pipe depth;
- Groundwater location... The higher they are, the better for geothermal heating. In this case, the temperature will increase with depth, which is the optimal condition for heating using the energy of the earth.
You also need to know about the possibility of reverse transfer of energy in the summer. Then the heating of a private house from the ground will not function, and the excess heat will transfer from the house to the soil. All refrigeration systems work according to the same principle. But for this you need to install additional equipment.
It is impossible to plan the installation of the external circuit at a distance from home. This will increase heat losses in heating from the bowels of the earth.
Horizontal geothermal heating scheme
The most common way to install external highways. It is convenient for its ease of installation and the ability to relatively quickly replace faulty pipeline sections.
For installation according to this scheme, a collector system is used. For this, several contours are made, located at a minimum distance of 0.3 m from each other. They are connected by means of a collector, which supplies the heat carrier further to the heat pump. This will provide maximum energy supply for heating from the heat of the earth.
But at the same time, you need to take into account a number of important nuances:
- Large area of the personal plot. For a house of about 150 m², it must be at least 300 m²;
- Pipes are compulsorily determined to a depth below the level of soil freezing;
- With the possible movement of soil during spring floods, the likelihood of displacement of highways increases.
The defining advantage of heating from the heat of the earth of the horizontal type is the possibility of independent arrangement. In most cases, this does not require the involvement of special equipment.
For maximum heat transfer, it is necessary to use pipes with a high thermal conductivity - thin-walled polymer. But at the same time, you should consider ways of insulating heating pipes in the ground.
Vertical geothermal heating scheme
This is a more time-consuming way of organizing heating a private house from the ground. The pipelines are placed vertically in special wells. It is important to know that such a scheme is much more efficient than a vertical one.
Its main advantage is to increase the degree of water heating in the external circuit. Those. the deeper the pipes are located, the more the amount of earth heat for heating the house will enter the system. Another factor is the small area of the land plot. In some cases, the arrangement of the external geothermal heating circuit is carried out even before the construction of the house in the immediate vicinity of the foundation.
What difficulties can you face when obtaining energy from the earth for heating a house according to this scheme?
- Quantitative to qualitative... For a vertical arrangement, the length of the highways is much longer. It is compensated by the higher soil temperature. To do this, you need to make wells up to 50 m deep, which is a laborious job;
- Soil composition... For rocky ground, special drilling machines must be used. In loam, to prevent the well shattering, a protective shell made of reinforced concrete or thick-walled plastic is mounted;
- In the event of a malfunction or loss of tightness the repair process becomes more complicated... In this case, long-term interruptions in the operation of heating the house for the thermal energy of the earth are possible.
But despite the high primary costs and laboriousness of installation, the vertical arrangement of the highways is optimal. Experts advise using just such an installation scheme.
For the circulation of the coolant in the external circuit in a vertical system, powerful circulation pumps are needed.
Organization of geothermal heating
Consumers still have the main question - is it possible to use the heating of a country house with the energy of the earth as the main one? This is possible, but only with a professional approach at all stages - from calculation to installation and testing of the system.
First of all, you need to choose the right heat pump. Given their high cost, you should first perform all preliminary calculations of its characteristics. Only in this case, heating due to the thermal energy of the earth will have a maximum efficiency factor. Reliable manufacturers include Buderus, Vaillant and Veissman. The average cost of a heat pump for heating from the subsoil is about 360 thousand rubles with a rated power of 6 kW. More productive models can cost over 1 million rubles.
In addition to the cost, you need to pay attention to the material for the manufacture of pipes. To minimize heat losses in heating from the thermal energy of the earth, it is recommended to use the following:
- XLPE... Differs in low cost - optimal for horizontal schemes;
- Stainless steel pipe... It is used in heating with the help of thermal energy of the earth with a vertical arrangement of the outer circuit. It favorably differs from cross-linked polyethylene in its high thermal conductivity and mechanical strength. The disadvantage is the high cost.
For optimization, it is recommended to install external and internal temperature sensors, as well as a heat accumulator. This will minimize the cost of heating a private house of land energy.
Considering all these factors, in most cases, geothermal heating from the energy of the earth is installed as an additional one. Over time, the cost of components and the efficiency of heat pumps will increase - and only then can such systems be considered as the main ones.
An example of installing geothermal heating in a private house can be found by watching the video:
