Geothermal heating is one of the most promising of the total number of alternative sources of energy. Unlike solar systems, it is practically independent of the time of year. But is heating a house beneficial due to the heat and energy of the earth?
Geothermal home heating
First you need to understand the principles of obtaining thermal energy. They are based on a rise in temperature when deepening deep into the earth. At first glance, the increase in the degree of heating is insignificant. But thanks to the advent of new technologies, home heating due to 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 indicator of external temperature; therefore, they are rarely used. How can it be practically possible to organize heating of a house by the energy of the earth?
To do this, you need to make 3 circuits filled with liquids with different technical characteristics:
- Outer. More often in it antifreeze circulates. Its heating to a temperature of at least 6 ° C is due to the energy of the earth;
- Heat pump. Without it, heating due to the energy of the earth is impossible. The coolant from the external circuit transfers its energy to the refrigerant using a heat exchanger. 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. According to a similar scheme, heat is transferred from the compressed refrigerant to water in the baking system. Thus, heating occurs from the bowels of the earth with minimal cost.
Despite the obvious advantages, such systems can rarely be found. This is associated with high costs for the purchase of equipment and the organization of the external circuit of the heat intake.
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.
The principle of operation of the heat pump
The “heart” of geothermal heating is the heat pump. It consists of several components, the operation of which directly affects the efficiency indicator of the entire system. Therefore, before planning the heating of a private house from the ground - you need to find out the main characteristics of this site.
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. It is necessary to create high pressure in the refrigerant medium;
- 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 mode of operation, the speed of passage of coolants, etc.
The main problem in the self-production of a heat pump is to reduce heat loss and normalize the operation of the internal circuit with refrigerant. 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, find out the thermal power of the pump. For an approximate calculation, you can use the following formula:
Q = (t1-t2) * V
Where t1-t2 - the temperature difference at the inlet and return pipe, ° C,V - estimated flow rate of the coolant, m³ / h,Q - rated power of the heat pump, watts.
This technique is not applicable for complex systems, since there are many additional factors. In particular, heat losses on the highway. This is especially true for those areas where it exits as close to the ground surface as possible. To minimize heat loss, warm 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.
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 can be a source of thermal energy - underground, water or air. But it is important to take into account seasonal changes in weather conditions, as discussed above.
Currently, there are two types of systems that are effectively used for heating a house due to the heat of the earth - horizontal and vertical. The key factor of choice is the size of the land. The layout of the pipes for heating a house with earth energy depends on this.
In addition to it, such factors are taken into account:
- Soil composition. In rocky and loamy it is difficult to make vertical trunks for laying highways;
- Soil freezing. He will determine the optimal depth of the pipe;
- 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 due to the energy of the earth.
You also need to know about the possibility of reverse energy transfer in the summer. Then the heating of a private house from the ground will not function, and excess heat will pass from the house to the soil. All refrigeration systems work in the same way. But for this it is necessary to install additional equipment.
You can’t plan to install an external circuit away from home. This will increase the heat loss in heating from the bowels of the earth.
Horizontal scheme of geothermal heating
The most common way to install external highways. It is convenient for ease of installation and the ability to relatively quickly replace faulty sections of the pipeline.
For installation according to this scheme, a collector system is used. To do this, several circuits are located located at a minimum distance of 0.3 m from each other. They are connected by means of a collector, which feeds the coolant further into the heat pump. This will ensure maximum energy input to the heating from the heat of the earth.
But at the same time, a number of important nuances must be taken into account:
- Large area of the plot. For a house of about 150 m², it should be at least 300 m²;
- Pipes are necessarily recessed to a depth below the level of soil freezing;
- With possible soil movement during spring floods, the likelihood of displacement of highways increases.
The defining advantage of heating from the heat of the earth of horizontal type is the possibility of self-arrangement. In most cases, this will not require the involvement of special equipment.
For maximum heat transfer, you need to use pipes with a high thermal conductivity - thin-walled polymer. But at the same time, ways to warm the heating pipes in the ground should be considered.
Vertical geothermal heating
This is a more laborious way of organizing heating a private house from the ground. Pipelines are located vertically in special wells. It is important to know that such a scheme is much more effective than a vertical one.
Its main advantage is to increase the degree of heating of water in the external circuit. Those. the deeper the pipes are located, the greater the amount of land heat for heating the house will enter the system. Another factor is the small area of the land. 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 one encounter in obtaining the energy of the earth for heating a house according to this scheme?
- Quantitative to qualitative. For vertical arrangement, the length of the lines is much higher. It is compensated by 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 soil, it is necessary to use special drilling machines. In the loam to prevent shedding of the well, a protective shell of reinforced concrete or thick-walled plastic is mounted;
- In case of malfunctions or loss of tightness the repair process is complicated. In this case, there may be long-term malfunctions in the work of heating the house for the thermal energy of the earth.
But despite the large initial costs and the complexity of installation, the vertical layout of the lines 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? It 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 must 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 coefficient of efficiency. Among the reliable manufacturers are 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 more than 1 million rubles.
In addition to cost, you need to pay attention to the material of the manufacture of pipes. To minimize heat loss in heating from the heat energy of the earth, it is recommended to use the following:
- Crosslinked Polyethylene. Differs in low cost - it is optimum for horizontal schemes;
- Stainless steel pipe. It is used in heating using the thermal energy of the earth with a vertical arrangement of the external circuit. It compares favorably with cross-linked polyethylene with a high thermal conductivity and mechanical strength. The disadvantage is the high cost.
For optimization, the installation of external and internal temperature sensors, as well as a heat accumulator, is recommended. This will minimize the cost of heating a private home energy land.
Given all these factors, so far in most cases they install geothermal heating from the energy of the earth as an additional. 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 the installation of geothermal heating in a private house can be found by watching the video:
