Heat pumps for heating your home. Heat pump in home heating Installation of a heat pump for home heating

Combustion of classic fuels (gas, wood, peat) is one of the ancient ways of producing heat. However, the depletion of traditional energy sources has prompted people to look for more complex, but no less effective alternatives. One of them was the invention of a heat pump, the operation of which is based on the school laws of physics.

Heat pump operation

The operating principle of heat pumps, which is very complex at first glance, is based on several simple laws of thermodynamics and the properties of liquids and gases:

  1. When a gas changes to a liquid state (condensation), heat is released
  2. When a liquid changes to gas (evaporation), heat is absorbed

Most liquids can boil at fairly high temperatures, close to 100 degrees. But there are also substances with fairly low boiling points. For freon it is about 3-4 degrees. Turning into gas, it is easily compressed and the temperature inside the container begins to rise.

Theoretically, freon can be compressed to obtain any desired temperatures, but in practice it is limited to 80-90 degrees necessary for the full operation of a classical heating system.

Everyone encounters a heat pump more than once a day when they pass by their refrigerator. However, in it it works in the opposite direction, taking the heat of the products and dissipating it into the atmosphere.

Video about working technology

Heat pump diagram

The performance of most heat pumps is based on the heat of the soil, in which the temperature practically does not fluctuate throughout the year (within 7-10 degrees). Heat moves between three circuits:

  1. Heating circuit
  2. Heat pump
  3. Brine (aka earthen) circuit

The classic operating principle of heat pumps in a heating system consists of the following elements:

  1. Heat exchanger that transfers heat taken from the ground to the internal circuit
  2. Compression device
  3. A second heat exchange device that transfers the energy received in the internal circuit to the heating system
  4. Mechanism that reduces pressure in the system (throttle)
  5. Brine circuit
  6. Earth probe
  7. Heating circuit

The pipe, which serves as the primary circuit, is placed in a well or buried directly in the ground. A non-freezing liquid coolant moves along it, the temperature of which rises to a similar characteristic of the earth (about +8 degrees) and enters the second circuit.

The secondary circuit takes heat from the liquid. The freon circulating inside begins to boil and is converted into gas, which is sent to the compressor. The piston compresses it to 24-28 atm, due to which the temperature increases to +70-80 degrees.

At this working stage, energy is concentrated into one small clot. Due to this, the temperature increases.

The heated gas enters the third circuit, which is represented by hot water supply systems or even home heating systems. During heat transfer, losses of up to 10-15 degrees are possible, but they are not significant.

When freon cools, the pressure decreases and it turns back into a liquid state. At a temperature of 2-3 degrees it flows back into the second circuit. The cycle repeats itself over and over again.

Main types

The operating principle of heat pumps is designed so that they can be easily operated without interruption in a wide temperature range - from -30 to +40 degrees. The following two types of models are most popular:

  • Absorption type
  • Compression type

Absorption-type models have a rather complex structure. They transfer the received thermal energy directly using the source. Their operation significantly reduces material costs for consumed electricity and fuel. Compression-type models consume energy (mechanical and electrical) to transfer heat.

Depending on the heat source used, pumps are divided into the following types:

  1. Recycling waste heat- the most expensive models that have gained popularity for heating industrial facilities, in which secondary heat generated by other sources is wasted.
  2. Air– taking heat from the surrounding air
  3. Geothermal– select heat from water or earth

According to the types of input/output, all models can be classified as follows - soil, water, air and their various combinations.

Geothermal heat pumps

Popular are geothermal pump models, which are divided into two types: closed or open type.

The simple design of open systems allows the water passing inside to be heated, which subsequently re-enters the ground. It works ideally in the presence of an unlimited volume of clean coolant liquid, which, after consumption, does not harm the environment.

Closed-loop systems of geothermal heat pumps are divided into the following types:

  • Water – located in a reservoir at an unfrozen depth
  • With a vertical arrangement - the collector is placed in a well to a depth of up to 200 m and is applicable in areas with uneven terrain
  • With a horizontal arrangement - the collector is placed in the ground to a depth of 0.5-1 m, it is very important to provide a large contour in a limited area

Air-water pump

One of the most versatile options is the air-to-water model. During warm periods of the year it is very effective, but in winter productivity can drop significantly.

The advantage of the system is its simple installation. Suitable equipment can be mounted in any convenient place, for example, on the roof. The heat that is removed from the room in the form of gas or smoke can be reused.

Water-to-water type

The water-to-water heat pump is one of the most efficient. But its use may be limited by the presence of a nearby reservoir or insufficient depth, at which a significant drop in temperature is not observed in winter.

Low potential energy can be selected from the following sources:

  • Ground water
  • Open reservoirs
  • Industrial waste water

The simplest principle of operation of heat pumps is for models that extract heat from a reservoir. If the decision is made to use groundwater, it may be necessary to drill a well.

Soil-water type

Heat can be obtained from the ground throughout the year, since at depths of 1 m the temperature remains virtually unchanged. “Brine” is used as a heat carrier - a non-freezing liquid that circulates.

One of the disadvantages of the ground-water system is the need for a large area to achieve the desired efficiency. They try to level it out by laying pipes in rings.

The collector can be placed in a vertical position, but a well up to 150 m deep will be required. Umbrellas are installed at the bottom to collect heat from the ground.

Pros and cons of heat pump heating systems

Heat pumps are widely used in heating systems for private residential or industrial areas. They are gradually replacing more classical energy sources due to their reliability and efficiency.

Among the many benefits that operating a heat pump provides are:

  • Saving material resources on system maintenance and coolant
  • The pumps operate completely autonomously
  • No harmful combustion products or other toxic substances are released into the environment
  • Fire safety of mounted equipment
  • Ability to easily reverse system operation

Despite the many advantages, it is necessary to take into account the negative aspects of using a heat pump:

  • Large initial investments for the installation of a heating system - from 3 to 10 thousand dollars
  • During cold periods, when temperatures drop below -15 degrees, you need to think about alternative heating options
  • Heating based on the operation of a heat pump is most effective only in systems with low-temperature coolant

Another schematic video:

Let's sum it up

Having learned and mastered the principle of operation of a heat pump, you can think and decide on the advisability of its installation and use. The initial costs, which may seem very large, will soon pay off and begin to bring a kind of profit in the form of savings on classic fuel.

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A unit such as a heat pump has a similar operating principle to household appliances - a refrigerator and an air conditioner. It borrows approximately 80% of its power from the environment. The pump pumps heat from the street into the room. Its operation is similar to the principle of operation of a refrigerator, only the direction of transfer of thermal energy is different.

For example, to cool a bottle of water, people put it in the refrigerator, then the household appliance partially “takes” the heat from this object and now, according to the law of conservation of energy, must release it. But where? Everything is simple, for this purpose the refrigerator has a radiator, usually located on its back wall. In turn, the radiator, heating up, gives off heat to the room in which it stands. Thus, the refrigerator heats the room. The degree to which it warms up can be felt in small shops in the hot summer, when several refrigeration units are turned on.

And now a little imagination. Suppose that warm objects are constantly placed in the refrigerator, and it heats the room, or it is placed in a window opening, the freezer door is opened outward, and the radiator is in the room. During its operation, the household appliance, cooling the air outside, will simultaneously transfer the thermal energy that exists outside into the building. This is exactly the principle of operation of a heat pump.

Where does the pump get heat from?

The heat pump operates thanks to the exploitation of natural low-potential sources of thermal energy, including:
  • ambient air;
  • bodies of water (rivers, lakes, seas);
  • soil and ground artesian and thermal waters.

Heating system with heat pump

When a heat pump is used for heating, its operating principle is based on integration into the heating system. It consists of two circuits, to which is added a third, which is a pump design.

The coolant, which absorbs heat from the environment, circulates along the external circuit. It enters the pump evaporator and releases approximately 4 -7 °C to the refrigerant, despite the fact that its boiling point is -10 °C. As a result, the refrigerant boils and then goes into a gaseous state. The already cooled coolant in the external circuit is sent to the next turn to set the temperature.

The heat pump functional circuit consists of:

  • evaporator;
  • refrigerant;
  • electric compressor;
  • capacitor;
  • capillary;
  • thermostatic control device.
The process of how a heat pump works looks something like this:
  • After boiling, the refrigerant, moving through the pipeline, enters the compressor, which operates using electricity. This device compresses the gaseous refrigerant to high pressure, causing its temperature to rise;
  • the hot gas enters another heat exchanger (condenser), in which the heat of the refrigerant is transferred to the coolant circulating through the internal circuit of the heating system, or to the air in the room;
  • cooling, the refrigerant turns into a liquid state, after which it passes through the capillary pressure reducing valve, losing pressure, and then again ends up in the evaporator;
  • thus, the cycle has ended and the process is ready to repeat.

Approximate calculation of heating output

Over the course of an hour, 2.5-3 cubic meters of coolant passes through the pump through the external collector, which the earth is able to heat by ∆t = 5-7 °C (read also: " "). To calculate the thermal power of a given circuit, you should use the formula:

Q = (T 1 - T 2) x V, where:
V – coolant flow per hour (m 3 /hour);
T 1 - T 2 - temperature difference between inlet and inlet (°C).

Types of heat pumps

Depending on the type of dissipated heat consumed, heat pumps are:
  • ground-water - for their operation in a water heating system, closed ground contours or geothermal probes located at depth are used (more details: " ");
  • water-water - the principle of operation in this case is based on the use of open wells for collecting groundwater and discharging it (read: " "). In this case, the external circuit is not looped, and the heating system in the house is water;
  • water-air - install external water circuits and use air-type heating structures;
  • air-to-air - for their operation, they use the dissipated heat of external air masses plus the air heating system of the house.

Advantages of heat pumps

  1. Cost-effective and efficient. The principle of operation of the heat pumps shown in the photo is based not on the production of thermal energy, but on its transfer. Thus, the efficiency of the heat pump must be greater than unity. But how is this possible? In relation to the operation of heat pumps, a value is used that is called the heat conversion coefficient, or abbreviated as CCT. The characteristics of units of this type are compared precisely according to this parameter.The physical meaning of the quantity is to determine the relationship between the amount of heat received and the energy expended to obtain it. For example, if the CPT coefficient is 4.8, this means that 1 kW of electricity expended by the pump produces 4.8 kW of heat, free of charge from nature.
  2. Universal universal application. If there are no power lines accessible to consumers, the pump compressor is operated using a diesel drive. Since natural heat is everywhere, the operating principle of this device allows it to be used everywhere.
  3. Environmental friendliness. The operating principle of the heat pump is based on low electricity consumption and the absence of combustion products. The refrigerant used by the unit does not contain chlorocarbons and is completely ozone-safe.
  4. Bidirectional mode of operation. During the heating season, the heat pump is able to heat the building and cool it in the summer. The heat taken from the room can be used to provide the house with hot water supply, and, if there is a swimming pool, to heat the water in it.
  5. Safe operation. There are no dangerous processes in the operation of heat pumps - there is no open fire, and substances harmful to human health are not released. The coolant does not have a high temperature, which makes the device safe and at the same time useful in everyday life.
  6. Automatic control of the room heating process.

 The principle of operation of a heat pump, a fairly detailed video:

Some features of pump operation

To ensure efficient operation of the heat pump, a number of conditions must be met:
  • the room must be well insulated (heat loss cannot exceed 100 W/m²);
  • It is advantageous to use a heat pump for low-temperature heating systems. The underfloor heating system meets this criterion, since its temperature is 35-40°C. The CPT largely depends on the relationship between the temperature of the input circuit and the output circuit.

The operating principle of heat pumps is to transfer heat, which allows you to obtain an energy conversion coefficient of 3 to 5. In other words, every 1 kW of electricity used brings 3-5 kW of heat into the house.

A heat pump is a universal device that functionally combines the characteristics of an air conditioner, water heater and heating boiler. This device does not use conventional fuel; its operation requires renewable sources from the environment - energy from air, soil, water.

Therefore, a heat pump today is the most cost-effective unit, since its operation does not depend on the cost of fuel, and is also environmentally friendly, since the source of heat is not electricity or combustion products, but natural heat sources.

To better understand how a heat pump works for heating a home, it is worth remembering the principle of operation of a refrigerator. Here the working substance evaporates, releasing cold. In the pump, on the contrary, it condenses and produces heat.

Working principle of a heat pump

The entire process of the system is presented in the form of a Carnot cycle - named after the inventor. It can be described as follows. The coolant passes through the working circuit - air, earth, water, and their combinations , from where it is sent to the 1st heat exchanger - the evaporation chamber. Here it transfers the accumulated heat to the refrigerant circulating in the internal circuit of the pump.

Operating principle of a home heating heat pump

The liquid refrigerant enters the evaporation chamber, where low pressure and temperature (5 0 C) transform it into a gaseous state. The next stage is the transfer of gas to the compressor and its compression. As a result, the temperature of the gas increases sharply, the gas passes into the condenser, here it exchanges heat with the heating system. The cooled gas turns into liquid and the cycle repeats.

Advantages and disadvantages of heat pumps

The operation of heat pumps for heating a home can be controlled using specially installed thermostats. The pump automatically turns on when the medium temperature drops below a set value and turns off if the temperature exceeds a set point. Thus, the device maintains a constant temperature in the room - this is one of the advantages of the devices.

The advantages of the device are its efficiency - the pump consumes a small amount of electricity and environmental friendliness, or absolute safety for the environment. Main advantages of the device:

  • Reliability. The service life exceeds 15 years, all parts of the system have a high working life, energy fluctuations do not harm the system.
  • Safety. There is no soot, exhaust, open flame, gas leakage is excluded.
  • Comfort. The operation of the pump is silent, climate control and an automatic system, the operation of which depends on weather conditions, help create coziness and comfort in the house.
  • Flexibility. The device has a modern, stylish design and can be combined with any home heating system.
  • Versatility. Used in private and civil construction. Because it has a wide power range. Due to this, it can provide heat to rooms of any size - from a small house to a cottage.

The complex structure of the pump determines its main disadvantage - the high cost of equipment and its installation. To install the device, it is necessary to carry out excavation work in large volumes.

Heat pumps - classification

The operation of a heat pump for heating a house is possible in a wide temperature range - from -30 to +35 degrees Celsius. The most common devices are absorption (transfer heat through its source) and compression (circulation of the working fluid occurs due to electricity). Absorption devices are the most economical, but they are more expensive and have a complex design.

Classification of pumps by type of heat source:

  1. Geothermal. They take away the heat of water or earth.
  2. Airborne. They take away heat from the atmospheric air.
  3. Secondary heat. They take away the so-called industrial heat - generated during production, heating, and other industrial processes.

The coolant can be:

  • Water from an artificial or natural reservoir, groundwater.
  • Priming.
  • Air masses.
  • Combinations of the above media.

Geothermal pump - principles of design and operation

A geothermal pump for heating a house uses the heat of the ground, which it selects with vertical probes or a horizontal collector. The probes are placed at a depth of up to 70 meters, the probe is located at a short distance from the surface. This type of device is the most effective because the heat source has a fairly high, constant temperature throughout the year. Therefore, it is necessary to spend less energy to transport heat.

Such equipment requires high installation costs. The cost of drilling wells is high. In addition, the area allocated for the collector must be several times larger than the area of ​​the heated house or cottage. Important to remember: the land where the collector is located cannot be used for planting vegetables or fruit trees - the roots of the plants will be supercooled.

Using water as a heat source

A body of water is a source of large amounts of heat. For the pump, you can use non-freezing reservoirs from 3 meters deep or groundwater at a high level. The system can be implemented as follows: the heat exchanger pipe, weighed down with a load at the rate of 5 kg per 1 linear meter, is laid on the bottom of the reservoir. The length of the pipe depends on the footage of the house. For a room of 100 sq.m. The optimal pipe length is 300 meters.

In the case of using groundwater, it is necessary to drill two wells, located one after the other in the direction of the groundwater. A pump is placed in the first well, supplying water to the heat exchanger. Cooled water flows into the second well. This is the so-called open heat collection circuit. Its main disadvantage is that the groundwater level is unstable and can vary significantly.

Air is the most accessible source of heat

When using air as a heat source, the heat exchanger is a radiator, forcedly blown by a fan. If a heat pump is used to heat a house using an air-to-water system, the user receives the following benefits:

  • Possibility to heat the entire house. Water, acting as a coolant, is distributed through heating appliances.
  • With minimal energy costs, it is possible to provide residents with hot water supply. This is possible due to the presence of an additional heat-insulated heat exchanger with a storage tank.
  • Pumps of a similar type can be used to heat water in swimming pools.

If the pump operates on an air-to-air system, the coolant is not used to heat the room. Heating is carried out using the received thermal energy. An example of the implementation of such a scheme would be a conventional air conditioner set to heating mode. Today, all devices that use air as a heat source are inverter-based. In them, alternating current is converted into direct current, providing flexible control of the compressor and its operation without stopping. And this increases the resource of the device.

Heat pump - an alternative home heating system

Heat pumps are an alternative to modern heating systems. They are economical, environmentally friendly and safe to use. However, the high cost of installation work and equipment today does not allow the devices to be used everywhere. Now you know how a heat pump works for heating a house, and after calculating all the pros and cons, you can decide whether to install it.

Heat pump (HP) is a device that carries out the transfer, transformation and conversion of thermal energy. According to the principle of operation, it is similar to well-known devices and equipment, such as a refrigerator or air conditioner. The operation of any TN is based on the reverse Carnot cycle, named after the famous French physicist and mathematician Sidi Carnot.

Working principle of a heat pump

Let's study in more detail the physics of the operating processes of this equipment. The heat pump consists of four main elements:

  1. Compressor
  2. Heat exchanger (condenser)
  3. Heat exchanger (evaporator)
  4. Connecting fittings and automation elements.

Compressor necessary to compress and move refrigerant through the system. When freon is compressed, its temperature and pressure rise sharply (pressure develops up to 40 bar, temperature up to 140 C), and in the form of a gas with a high degree of compression it goes to the capacitor(adiabatic process, i.e. a process in which the system does not interact with external space), where it transfers energy to the consumer. The consumer can be either the immediate environment that needs to be heated (for example, indoor air) or the coolant (water, antifreeze, etc.), which then distributes energy through the heating system (radiators, heated floors, heated baseboards, convectors, fan coils, etc.). In this case, the temperature of the gas naturally decreases, and it changes its state of aggregation from gaseous to liquid (an isothermal process, i.e. a process occurring at a constant temperature).

Next, the refrigerant is in a liquid state enters the evaporator, passing through a thermostatic valve (TRV), which is necessary to reduce the pressure and dose the flow of freon into the evaporative heat exchanger. As a result of a decrease in pressure when passing through the evaporator channels, a phase transition occurs, and the state of aggregation of the refrigerant again changes to gaseous. In this case, the entropy of the gas decreases (based on the thermophysical properties of freons), which leads to a sharp drop in temperature, and heat is “removed” from an external source. The external source can be street air, the bowels of the earth, rivers, lakes. Next, the cooled gaseous freon is returned to the compressor, and the cycle repeats again.

In fact, it turns out that the heat engine itself does not produce heat, but is a device for moving, modifying and modifying energy from the environment into the room. However, this process requires electricity, the main consumer of which is the compressor unit. The ratio of the received thermal power to the expended electrical power is called the conversion factor (COR). It varies depending on the type of turbocharger, its manufacturer, and other factors and ranges from 2 to 6.

Currently, various types of ozone-friendly freons (R410A, R407C) are used as a refrigerant, which cause minimal damage to the environment.

Modern heat engines use scroll-type compressors that require no maintenance, have virtually no friction, and can operate continuously for 30-40 years. This ensures a long service life of the entire unit. For example, a German company Stiebel Eltron There are HPs that have operated without major repairs since the early 70s of the last century.

Types of Heat Pumps

Depending on the media used for the selection and redistribution of energy, as well as design features and methods of application, there are four main types of HP:

Air-to-air heat pump

This type of equipment uses street air as a low-potential energy source. Outwardly, it does not differ from a conventional split air conditioning system, but it has a number of functional features that allow it to operate at low temperatures (down to -30 C) and “remove” energy from the environment. The house is heated directly by warm air heated in the heat pump condenser.

Advantages of air-to-air HP:

  • Low cost
  • Short installation time and comparative ease of installation
  • No possibility of coolant leakage

Flaws:

  • Stable performance down to -20 C
  • The need to install an indoor unit in each room or organize an air duct system to supply heated air to all rooms.
  • Inability to obtain hot water (DHW)

In practice, such systems are used for seasonal housing and cannot act as the main source of heating.

Air-to-water heat pump

Their operating principle is similar to the previous type, however, they do not directly heat the air inside the room, but the coolant, which in turn is used to heat the house and prepare hot water.

Advantages of TN “Air – Water”:

  • does not require the organization of an “external contour” (drilling)
  • reliability and durability
  • high efficiency indicators (COP) in the autumn and spring periods

Disadvantages of TN:

  • Significant reduction in COP at low temperatures (up to 1.2)
  • The need to defrost the external unit (reverse mode)
  • Inability to operate at temperatures below -25 C - -30 C

Such pumps in our climate still cannot act as the only source of heating. Therefore, they are often installed (according to a bivalent scheme) in conjunction with additional heating equipment (electric, pellet, solid fuel, diesel boiler, fireplace with a water jacket). They are also suitable for the reconstruction and automation of old boiler houses using traditional fuels. This allows the system to be operated in automatic mode for most of the year (there is no need to load solid fuel or refuel diesel fuel), using only the power of the HP.

Brine-water heat pump

One of the most common in the Republic of Belarus. Using statistics from our organization, 90% of installed heat pumps are geothermal. In this case, the bowels of the earth are used as the “external contour”. Due to this, these heat pumps have the most important advantage over other types of heat pumps - a stable operating efficiency indicator (COP) regardless of the time of year.

According to established terminology, the external circuit is called geothermal.

There are two main types of geothermal circuit:

  • Horizontal
  • Vertical

Let's look at each of them in more detail.

Horizontal outline

Horizontal outline is a system of polyethylene pipes laid under the top layer of soil at a depth of about 1.5 - 2 m, below the freezing level. The temperature in this zone remains positive (from +3 to +15 C) throughout the calendar year, reaching a maximum in October and a minimum in May. The area occupied by the collector depends on the area of ​​the building, the degree of its insulation, and the size of the glazing. So, for example, for a two-story residential building with an area of ​​200 m2, which has good insulation that meets modern standards, about four acres of land (400 m2) will have to be allocated for a geothermal field. Of course, for a more accurate assessment of the diameter of the pipes used and the occupied area, a detailed thermal engineering calculation is required.

This is what the installation of a horizontal collector looks like at one of our facilities in Dzerzhinsk (Republic of Belarus):


Advantages of a horizontal collector:

  • Lower cost compared to geothermal wells
  • Possibility of carrying out work on its installation together with the laying of other communications (water supply, sewerage)

Disadvantages of a horizontal collector:

  • Large occupied area (it is prohibited to erect permanent structures, asphalt, lay paving slabs, it is necessary to ensure natural access to light and precipitation)
  • Lack of possibility of arrangement with ready-made landscape design of the site
  • Less stability compared to a vertical collector.

The arrangement of this type of collector is usually carried out in two ways. In the first case over the entire laying area, remove the top layer of soil, 1.5-2m thick, the heat exchanger pipes are being laid out with a given step (from 0.6 to 1.5 m) and backfilling is carried out. To perform such work, powerful equipment is suitable, such as a front loader, bulldozer, excavators with a large reach and bucket volume.

In the second case laying the ground contour loops is carried out step by step in prepared trenches, width from 0.6 m to 1 m. Small excavators and backhoe loaders are suitable for this purpose.

Vertical outline

Vertical collector represents wells with depths from 50 to 200 m and more, into which special devices are lowered - geothermal probes. The temperature in this zone remains constant for many years and decades and increases with increasing depth. The increase occurs on average by 2-5 C for every 100 m. This characterizing value is called the temperature gradient.

The process of installing a vertical collector at our facility in the village of Kryzhovka, near Minsk:


Studying maps of temperature distribution at various depths on the territory of the Republic of Belarus and the city of Minsk in particular, one can notice that the temperature varies from region to region, and can differ significantly depending on location. So, for example, at a depth of 100 m in the area of ​​Svetlogorsk it can reach +13 C, and in some areas of the Vitebsk region at the same depth it does not exceed +8.5 C.

Of course, when calculating the drilling depth and designing the size, diameter and other characteristics of geothermal probes, it is necessary to take this factor into account. In addition, it is necessary to take into account the geological composition of the rocks being passed through. Only based on this data can you correctly design a geothermal circuit.

As the practice and statistics of our organization show, 99% of problems during the operation of HP are associated with the functioning of the external circuit, and this problem does not appear immediately after commissioning of the equipment. And there is an explanation for this, because if the geocontour is incorrectly calculated (for example, in the territory of the Vitebsk region, where, as we remember, the geothermal gradient is one of the lowest in the Republic), its initial work is not satisfactory, but over time the thickness of the earth “cools”, The thermodynamic balance is disrupted and troubles begin, and the problem can arise only in the second or third heating season. An oversized contour looks less problematic, but the customer is forced to pay for unnecessary meters of drilling due to the incompetence of the contractor, which inexorably leads to an increase in the cost of the entire project.

The study of the subsoil of the earth should be especially critical during the construction of large commercial facilities, where the number of wells is in the dozens, and the funds saved (or wasted) on their construction can be very significant.

Water-to-water heat pump

One type of geothermal heat source can be groundwater. They have a constant temperature (from +7 C and above), and occur in significant quantities at various depths in the territory of the Republic of Belarus. According to the technology, groundwater is lifted from a well by a centrifugal pump and enters a heat and mass transfer station, where it transfers energy to the antifreeze of the lower circuit of the heat pump. The operating efficiency of this system depends on the level of groundwater (depending on the depth of rise, a certain pump power is required), and the distance from the intake well to the exchange station. This technology has one of the highest COP values, but has a number of features that limit its use.

Among them:

  • Lack of groundwater, or low level of its occurrence;
  • Lack of constant well flow, decrease in static and dynamic levels;
  • The need to take into account the salt composition and contamination (if the water quality is not adequate, the heat exchanger becomes clogged and performance indicators decrease)
  • The need to install a drainage well to discharge significant volumes of waste water (from 2200 l/h or more)

As practice shows, the installation of such systems is advisable if there is a pond or river in the immediate vicinity. Waste water can also be used for economic and industrial purposes, for example, for irrigation, or for organizing artificial reservoirs.

As for the quality of intake water, for example, a German manufacturer of alternative heating systems Stiebel Eltron recommends the following settings: the total proportion of iron and magnesium is not more than 0.5 mg/l, the chloride content is less than 300 mg/l, the absence of precipitated substances. If these parameters are exceeded, it is necessary to install an additional purification system - a preparation and desalting station, which increases the material consumption of the project.

Drilling work for a heat pump.

Based on experience in the installation and operation of geothermal units, we recommend drilling wells of at least 100 m. Practice shows that better performance and stability of a heat engine will be observed, for example, for two wells of 150 m each than for three wells of 100 m each. Of course, the construction of such mines requires special equipment and a rotary drilling method. Small-sized auger installations are not able to provide the required length of wells.

Since the geothermal circuit is the most important component, and the correctness of its arrangement is the key to the successful functioning of the entire system, the drilling contractor must meet a number of criteria:

  • It is necessary to have experience in producing this type of service;
  • have a special tool for immersing probes;
  • provide a guarantee that the probe will be immersed to the designed depth and guarantee its integrity and tightness during the work process;
  • after immersion, carry out measures to plug the well to increase its heat transfer and productivity, caulk the shaft of the mine before backfilling.

In general, with proper design and qualified installation, geothermal probes are very reliable and can last up to 100 years.

The process of lowering a geothermal probe into a drilled well:


Geothermal probe on the frame, before performing a leak test (“pressure testing”):


conclusions

Based on our experience in the design of alternative energy systems, we can highlight the main facts that are fundamental when our Customers choose heat pumps:

  • full safety and environmental friendliness(no combustion processes or moving parts)
  • the opportunity to order the system “today” and enjoy using it in three weeks without any coordination with regulatory and licensing authorities.
  • Full autonomy and minimal maintenance(there is no need to be a member of a gas cooperative, to depend on it; there is no need to throw firewood or carry out monthly cleaning of air ducts, organize the access of a fuel tanker, etc.)
  • The cost of a plot for the construction of an individual house without gas supply is much lower and the delivery period does not depend on gas services
  • Opportunity remote control via the Internet
  • Advanced and innovative equipment of stylish design, which is not a shame to show to friends and acquaintances, which certainly emphasizes the status of the homeowner.

If we have not touched on any questions in this article and you want to ask them personally, you can come to our office at the address: Minsk, st. Odoevsky, 117, Nova Gros LLC and consult with our engineers.

We also have the opportunity to organize free visits to already completed operating facilities.

Contact telephone number: 044 765 29 58; 017 399 70 51

The situation is such that the most popular way to heat a home at the moment is the use of heating boilers - gas, solid fuel, diesel and much less often - electric. But such simple and at the same time high-tech systems as heat pumps have not become widespread, and for good reason. For those who love and know how to calculate everything in advance, their advantages are obvious. Heat pumps for heating do not burn irreplaceable reserves of natural resources, which is extremely important not only from the point of view of environmental protection, but also allows you to save on energy, as they become more expensive every year. In addition, with the help of heat pumps you can not only heat the room, but also heat hot water for household needs, and air condition the room in the summer heat.

Operating principle of a heat pump

Let's take a closer look at the principle of operation of a heat pump. Remember how a refrigerator works. The heat of the products placed in it is pumped out and thrown onto the radiator located on the rear wall. You can easily verify this by touching it. The principle of household air conditioners is approximately the same: they pump out heat from the room and throw it onto a radiator located on the outer wall of the building.

The operation of a heat pump, refrigerator and air conditioner is based on the Carnot cycle.

  1. The coolant, moving along a source of low-temperature heat, for example, soil, heats up by several degrees.
  2. It then enters a heat exchanger called an evaporator. In the evaporator, the coolant releases the accumulated heat to the refrigerant. Refrigerant is a special liquid that turns into steam at low temperatures.
  3. Taking on the temperature from the coolant, the heated refrigerant turns into steam and enters the compressor. The compressor compresses the refrigerant, i.e. an increase in its pressure, due to which its temperature also increases.
  4. The hot, compressed refrigerant enters another heat exchanger called a condenser. Here the refrigerant transfers its heat to another coolant, which is provided in the heating system of the house (water, antifreeze, air). This cools the refrigerant and turns it back into liquid.
  5. Next, the refrigerant enters the evaporator, where it is heated by a new portion of the heated coolant, and the cycle repeats.

The heat pump requires electricity to operate. But it is still much more profitable than using only an electric heater. Since an electric boiler or electric heater spends exactly the same amount of electricity as it produces heat. For example, if a heater has a power rating of 2 kW, then it spends 2 kW per hour and produces 2 kW of heat. A heat pump produces 3 to 7 times more heat than it consumes electricity. For example, 5.5 kW/hour is used to operate the compressor and pump, and the heat produced is 17 kW/hour. It is this high efficiency that is the main advantage of a heat pump.

Advantages and disadvantages of the heat pump heating system

There are many legends and misconceptions surrounding heat pumps, despite the fact that they are not such an innovative or high-tech invention. All “warm” states in the USA, almost all of Europe and Japan, where the technology has been worked out almost to perfection for a long time, are heated with the help of heat pumps. By the way, you should not think that such equipment is a purely foreign technology and came to us quite recently. After all, back in the USSR such units were used at experimental facilities. An example of this is the Druzhba sanatorium in the city of Yalta. In addition to the futuristic architecture, reminiscent of a “hut on chicken legs,” this sanatorium is also famous for the fact that since the 80s of the 20th century it has used industrial heat pumps for heating. The source of heat is the nearby sea, and the pumping station itself not only heats all the premises of the sanatorium, but also provides hot water, heats the water in the pool and cools it during the hot season. So let's try to dispel the myths and determine whether it makes sense to heat your home in this way.

Advantages of heating systems with a heat pump:

  • Energy savings. In connection with rising prices for gas and diesel fuel, this is a very relevant advantage. In the “monthly expenses” column, only electricity will appear, which, as we have already written, requires much less than the heat actually produced. When purchasing a unit, you need to pay attention to such a parameter as the heat transformation coefficient “ϕ” (may also be called the heat conversion coefficient, power or temperature transformation coefficient). It shows the ratio of the amount of heat output to the energy expended. For example, if ϕ=4, then at a consumption of 1 kW/hour we will receive 4 kW/hour of thermal energy.
  • Maintenance savings. The heat pump does not require any special treatment. Its maintenance costs are minimal.
  • Can be installed in any location. Sources of low-temperature heat for the operation of a heat pump can be soil, water or air. Wherever you build a house, even in a rocky area, there will always be an opportunity to find “food” for the unit. In areas remote from the gas main, this is one of the most optimal heating systems. And even in regions without power lines, you can install a gasoline or diesel engine to ensure the operation of the compressor.
  • No need to monitor pump operation, add fuel, as is the case with a solid fuel or diesel boiler. The entire heating system with heat pump is automated.
  • You can go away for a long time and not be afraid that the system will freeze. At the same time, you can save money by installing the pump to ensure a temperature of +10 °C in the living room.
  • Safe for the environment. For comparison, when using traditional boilers that burn fuel, various oxides CO, CO2, NOx, SO2, PbO2 are always formed, as a result, phosphoric, nitrous, sulfuric acids and benzoic compounds settle around the house on the soil. When the heat pump operates, nothing is emitted. And the refrigerants used in the system are absolutely safe.
  • It can also be noted here conservation of the planet's irreplaceable natural resources.
  • Safety for people and property. Nothing in a heat pump gets hot enough to cause overheating or explosion. Besides, there is simply nothing to explode in it. So it can be classified as a completely fireproof unit.
  • Heat pumps operate successfully even at an ambient temperature of -15 °C. So if someone thinks that such a system can only heat a house in regions with warm winters up to +5 °C, then they are mistaken.
  • Heat pump reversibility. An undeniable advantage is the versatility of the installation, with which you can heat in winter and cool in summer. On hot days, the heat pump takes heat from the room and sends it to the ground for storage, from where it will be taken back in the winter. Please note that not all heat pumps have reverse capability, but only some models.
  • Durability. With proper care, heat pumps in a heating system can last from 25 to 50 years without major repairs, and only once every 15 to 20 years will the compressor need to be replaced.

Disadvantages of heat pump heating systems:

  • Large initial investment. In addition to the fact that prices for heat pumps for heating are quite high (from 3,000 to 10,000 USD), you will also need to spend no less on the installation of a geothermal system than on the pump itself. An exception is the air source heat pump, which does not require additional work. The heat pump will not pay for itself soon (in 5 - 10 years). So the answer to the question of whether or not to use a heat pump for heating rather depends on the preferences of the owner, his financial capabilities and construction conditions. For example, in a region where supplying a gas main and connecting to it costs the same as a heat pump, it makes sense to give preference to the latter.

  • In regions where winter temperatures drop below -15 °C, additional heat source must be used. It is called bivalent heating system, in which the heat pump provides heat as long as it’s down to -20 °C outside, and when it can’t cope, for example, an electric heater or a gas boiler, or a heat generator is connected.

  • It is most advisable to use a heat pump in systems with low-temperature coolant, such as "warm floor" system(+35 °C) and fan coil units(+35 - +45 °C). Fan coil units They are a fan convector in which heat/cold is transferred from water to air. To install such a system in an old house, a complete redevelopment and reconstruction will be required, which will entail additional costs. This is not a disadvantage when building a new home.
  • Environmental friendliness of heat pumps, taking heat from water and soil, somewhat relative. The fact is that during operation, the space around the coolant pipes cools, and this disrupts the established ecosystem. After all, even in the depths of the soil, anaerobic microorganisms live, ensuring the vital functions of more complex systems. On the other hand, compared to gas or oil production, the damage from a heat pump is minimal.

Heat sources for heat pump operation

Heat pumps take heat from those natural sources that accumulate solar radiation during the warm period. Heat pumps vary depending on the heat source.

Priming

Soil is the most stable source of heat that accumulates over the season. At a depth of 5 - 7 m, the soil temperature is almost always constant and equal to approximately +5 - +8 ° C, and at a depth of 10 m it is always constant +10 ° C. There are two ways to collect heat from the ground.

Horizontal ground collector It is a horizontally laid pipe through which coolant circulates. The depth of the horizontal collector is calculated individually depending on the conditions, sometimes it is 1.5 - 1.7 m - the depth of soil freezing, sometimes lower - 2 - 3 m to ensure greater temperature stability and less difference, and sometimes only 1 - 1.2 m - here the soil begins to warm up faster in the spring. There are cases when a two-layer horizontal collector is installed.

Horizontal collector pipes can have different diameters: 25 mm, 32 mm and 40 mm. The shape of their layout can also be different - snake, loop, zigzag, various spirals. The distance between the pipes in the snake must be at least 0.6 m, and is usually 0.8 - 1 m.

Specific heat removal per linear meter of pipe depends on the soil structure:

  • Dry sand - 10 W/m;
  • Dry clay - 20 W/m;
  • Clay is wetter - 25 W/m;
  • Clay with a very high water content - 35 W/m.

To heat a house with an area of ​​100 m2, provided that the soil is wet clay, you will need 400 m2 of land area for the collector. This is quite a lot - 4 - 5 acres. And taking into account the fact that there should be no buildings on this site and only a lawn and flower beds with annual flowers are allowed, not everyone can afford to equip a horizontal collector.

A special liquid flows through the collector pipes, it is also called "brine" or antifreeze, for example, a 30% solution of ethylene glycol or propylene glycol. The “brine” collects the heat from the ground and is sent to the heat pump, where it transfers it to the refrigerant. The cooled “brine” flows again into the ground collector.

Vertical soil probe is a system of pipes buried to 50 - 150 m. This can be just one U-shaped pipe, lowered to a greater depth of 80 - 100 m and filled with concrete mortar. Or maybe a system of U-shaped pipes lowered 20 m to collect energy from a larger area. Carrying out drilling work to a depth of 100 - 150 m is not only expensive, but also requires obtaining a special permit, which is why they often resort to cunning and equip several probes of shallow depth. The distance between such probes is 5 - 7 m.

Specific heat removal from a vertical collector also depends on the rock:

  • Dry sedimentary rocks - 20 W/m;
  • Sedimentary rocks saturated with water and rocky soil - 50 W/m;
  • Rocky soil with a high thermal conductivity coefficient - 70 W/m;
  • Underground (groundwater) water - 80 W/m.

The area required for a vertical collector is very small, but the cost of their installation is higher than that of a horizontal collector. The advantage of a vertical collector is also a more stable temperature and greater heat removal.

Water

Water can be used as a heat source in different ways.

Collector at the bottom of an open, non-freezing reservoir- rivers, lakes, seas - represents pipes with “brine”, submerged with the help of a weight. Due to the high temperature of the coolant, this method is the most profitable and economical. Only those from whom the reservoir is located no further than 50 m can install a water collector, otherwise the efficiency of the installation is lost. As you understand, not everyone has such conditions. But not using heat pumps for coastal residents is simply short-sighted and stupid.

Collector in sewer drains or waste water from technical installations can be used for heating houses and even high-rise buildings and industrial enterprises within the city, as well as for preparing hot water. What is being done successfully in some cities of our Motherland.

Well or ground water used less frequently than other collectors. Such a system involves the construction of two wells, water is taken from one, which transfers its heat to the refrigerant in the heat pump, and cooled water is discharged into the second. Instead of a well, there may be a filtration well. In any case, the discharge well should be located at a distance of 15 - 20 m from the first one, and even downstream (groundwater also has its own flow). This system is quite difficult to operate, since the quality of the incoming water must be monitored - filtered, and protected from corrosion and contamination of the heat pump parts (evaporator).

Air

The simplest design is heating system with air source heat pump. No additional collector is needed. Air from the environment directly enters the evaporator, where it transfers its heat to the refrigerant, which in turn transfers heat to the coolant inside the house. This could be air for fan coil units or water for underfloor heating and radiators.

The installation costs of an air source heat pump are minimal, but the performance of the installation is highly dependent on the air temperature. In regions with warm winters (up to +5 - 0 °C) this is one of the most economical sources of heat. But if the air temperature drops below -15 °C, the performance drops so much that it makes no sense to use the pump, and it is more profitable to turn on a conventional electric heater or boiler.

Reviews on air source heat pumps for heating are very contradictory. It all depends on the region of their use. They are advantageous to use in regions with warm winters, for example, in Sochi, where there is no need for a backup heat source in case of severe frosts. It is also possible to install air source heat pumps in regions where the air is relatively dry and the temperature in winter is down to -15 °C. But in humid and cold climates, such installations suffer from icing and freezing. Icicles sticking to the fan prevent the entire system from working properly.

Heating with a heat pump: system cost and operating costs

The power of the heat pump is selected depending on the functions that will be assigned to it. If only heating, then calculations can be made in a special calculator that takes into account the heat losses of the building. By the way, the best performance of a heat pump is when the heat loss of the building is no more than 80 - 100 W/m2. For simplicity, we assume that to heat a house of 100 m2 with ceilings 3 m high and heat loss of 60 W/m2, a pump with a power of 10 kW is needed. To heat water, you will have to take a unit with a power reserve - 12 or 16 kW.

Heat pump cost depends not only on power, but also on reliability and the manufacturer’s requests. For example, a Russian-made 16 kW unit will cost $7,000, and a foreign pump RFM 17 with a power of 17 kW costs about $13,200. with all associated equipment except the manifold.

The next expense line will be reservoir arrangement. It also depends on the power of the installation. For example, for a house of 100 m2, in which heated floors (100 m2) or heating radiators of 80 m2 are installed everywhere, as well as to heat water to +40 °C with a volume of 150 l/hour, you will need to drill wells for collectors. Such a vertical collector will cost 13,000 USD.

A collector at the bottom of a reservoir will cost a little less. Under the same conditions, it will cost 11,000 USD. But it is better to check the cost of installing a geothermal system with specialized companies; it can vary greatly. For example, installing a horizontal collector for a 17 kW pump will cost only 2500 USD. And for an air source heat pump, a collector is not needed at all.

Total, the cost of the heat pump is 8000 USD. On average, the construction of a collector is 6000 USD. average.

The monthly cost of heating with a heat pump only includes electricity costs. They can be calculated as follows: the power consumption must be indicated on the pump. For example, for the above-mentioned 17 kW pump, the power consumption is 5.5 kW/h. In total, the heating system operates 225 days a year, i.e. 5400 hours. Taking into account the fact that the heat pump and compressor in it operate cyclically, the energy consumption must be halved. During the heating season, 5400h*5.5kW/h/2=14850 kW will be spent.

We multiply the number of kW spent by the cost of energy in your region. For example, 0.05 USD for 1 kW/hour. In total, 742.5 USD will be spent per year. For each month in which the heat pump worked for heating, it costs 100 USD. electricity costs. If you divide the expenses by 12 months, then you get 60 USD per month.

Please note that the lower the heat pump's power consumption, the lower the monthly costs. For example, there are 17 kW pumps that consume only 10,000 kW per year (costs 500 cu). It is also important that the performance of a heat pump is greater, the smaller the temperature difference between the heat source and the coolant in the heating system. That is why they say that it is more profitable to install warm floors and fan coil units. Although standard heating radiators with high-temperature coolant (+65 - +95 °C) can also be installed, but with an additional heat accumulator, for example, an indirect heating boiler. A boiler is also used to additionally heat the hot water.

Heat pumps are advantageous when used in bivalent systems. In addition to the pump, you can install a solar collector, which can fully supply the pump with electricity in the summer, when it works for cooling. For winter insurance, you can add a heat generator that will heat water for hot water supply and high-temperature radiators.