Heat pump for heating a house: how to choose. How to choose a heat pump for heating a house: prices, types, installation basics How a heat pump for heating a house works

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Extracting heat from soil and water sources is not such an innovation. The Western world has long used geothermal energy for home heating. This topic is becoming more and more relevant as utility prices increase. A heat pump for heating a home makes it possible to warm the radiators in an environmentally friendly, safe and free manner.

The heat pump heats the house with natural heat

Heat pump for heating a house: principle of operation, advantages and disadvantages

An example of a device similar to a heat pump is found in every home - this is a refrigerator. It produces not only cold, but also heat - this is noticeable by the temperature of the rear wall of the unit. A similar principle is inherent in the heat pump - it collects thermal energy from water, earth and air.

Operating principle and device

The operating system of the device is as follows:

• water from a well or reservoir passes through the evaporator, where its temperature drops by five degrees;
• after cooling, the liquid enters the compressor;
• the compressor compresses the water, increasing its temperature;
• the heated liquid moves into the heat exchange chamber, where it transfers its heat to the heating system;
• the cooled water returns to the beginning of the cycle.

Heating systems based on heat pump units have three components:

• A probe is a coil located in water or ground. It collects heat and transfers it to the device.
• A heat pump is a device that extracts thermal energy.
• The heating system itself, including a heat exchange chamber.

Pros and cons of the device

First, about the positive aspects of such heating:

• Relatively low energy consumption. Only electricity is consumed for heating, and it will require much less than, for example, heating with electrical appliances. Heat pumps have a conversion factor that indicates the output of thermal energy relative to the electrical energy expended. For example, if the value of “ϕ” is 5, then for 1 kilowatt per hour of electricity consumption there will be 5 kilowatts of thermal energy.

• Versatility. This heating system can be installed in any location. This is especially true for remote areas where there are no gas mains. If it is not possible to connect electricity, the pump can run on a diesel or gasoline engine.
• Full automation. There is no need to add water to the system or monitor its operation.
• Environmental friendliness and safety. The heat pump system does not produce any waste or gases. The device cannot accidentally overheat.
• Such a unit can not only heat a house in winter at air temperatures down to minus fifteen degrees, but also cool it in summer. Such functions are available in reverse models.

• Long period of operation - up to half a century. The compressor may need to be replaced approximately every twenty years.

This system also has its drawbacks, which cannot be ignored:

• Prices. A heat pump for heating a home is not a cheap pleasure. This system will pay for itself no sooner than in five years.
• In areas where winter temperatures drop below fifteen degrees below zero, additional heat sources (electric or gas) will be required for the operation of the device.
• A system that takes thermal energy from the ground disrupts the ecosystem of the site. The damage is not significant, but this should be taken into account.

Expert's point of view

Andrey Starpovsky

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“If you wish, you can make a heat pump for heating your home from a refrigerator with your own hands. But this will require certain technical knowledge.”

Which pump to choose

Installations differ in the source of thermal energy and the method of its transmission. There are five main types:

• Water-air.
• Ground-water.
• Air-to-air.
• Water-water.
• Air-water.

Site investigation

Before installing a heating system, it is important to examine the features of the site. This study will help determine which source of thermal energy will be the best option. The easiest way is if there is a pond near the house. This fact will free you from the need to carry out excavation work. Another practical solution is to use an area where the wind constantly blows. If there is neither one nor the other, you will have to stop at earthworks.

The heating system can have two installation options:

• using probes;
• with the installation of an underground collector.

Ground-water pump and installation options

Geothermal probes are usually installed in a small area that does not allow for a large pipeline to be installed. To install this system, you will need drilling equipment, since the depth of the wells must be at least one hundred meters and the diameter must be twenty centimeters. Probes are lowered into such wells. The number of wells affects the performance of the heating system.

If the area of ​​the site is large enough, you can do without drilling and install a horizontal system. For this purpose, the coil is buried to a depth of one and a half meters. This version of the system is considered the most stable and trouble-free.

Water-to-water pump: easy installation

A water-to-water heat pump for heating a house is suitable for areas with ponds. For the pipeline, you can use ordinary polyethylene pipes. The assembled collector is moved to the pond and lowered to the bottom there. This is one of the cheapest installation options that you can do yourself.

Air-to-air heat pump: installation cost

In an area where winds are constantly present, a system that uses air thermal energy is suitable. Installation in this case will also not require any special costs; you can do it yourself. You just need to install the pump no further than twenty meters from the house in the most ventilated place.

Heat pump for home heating: prices and manufacturers

Heat pump units on the Russian market are represented by products from the following companies: Vaillant (Germany), Nibe (Sweden), Danfoss (Denmark), Mitsubishi Electric (Japan), Mammoth (USA), Viessmann (Germany). Russian manufacturers SunDue and Henk are not inferior to them in quality.

To heat a house with an area of ​​one hundred square meters, a ten-kilowatt installation will be required.

Table 1. Average cost of different types of 10 kilowatt pumps

Image	Pump type	Cost of equipment, rub	Cost of installation work, rub
	Ground-water Imported manufacturers	From 500,000	From 80 000
	Ground water domestic producers	From 360,000	From 70 000
	Air-water Imported manufacturers	From 270,000	From 50 000
	Air-water Domestic producers	From 210,000	From 40 000
	Water-water imported manufacturers	From 230,000	From 50 000
	Water-water domestic producers	From 220,000	From 40 000

The turnkey price of a heat pump averages about 300 – 350 thousand rubles. The most budget-friendly option is the air-water system, since it does not require expensive excavation work.

Expert's point of view

Andrey Starpovsky

Head of the Heating, Ventilation and Air Conditioning Group, GRAST LLC

Ask a Question

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

A heat pump is a device that can provide your home with heating in the winter, cooling in the summer, and hot water production all year round.

A heat pump uses energy from renewable sources - heated air, earth, rock or water - to produce thermal energy. This transformation is carried out with the help of special substances -.

Operating principle of a heat pump

Structurally, any heat pump consists of two parts: an external one, which “takes” heat from renewable sources, and an internal one, which transfers this heat to the heating or air conditioning system of your home. Modern heat pumps are highly energy efficient, which in practical terms means the following - the consumer, i.e. A home owner using a heat pump spends, on average, only a quarter of the money he would spend on heating or cooling his home as if he did not have a heat pump.

In other words, in a system with a heat pump, 75% of useful heat (or cold) is provided from free sources - the heat of the earth, groundwater, or used air heated in the premises and discharged outside.

Let's look at how perhaps the most popular heat pump in everyday life works, powered by the heat of the earth. The heat pump operates in several cycles.

Cycle 1, evaporation

The outer part of the “earth” heat pump is a closed system of pipes buried in the ground to a certain depth, where the temperature is stable all year round and is 7-12°C. To “collect” a sufficient amount of earth’s energy, it is required that the total area occupied by the underground pipe system be 1.5-2 times larger than the entire heated area of ​​the house. These pipes are filled with refrigerant, which is heated to the temperature of the ground.

The refrigerant has a very low boiling point, so it can go into a gaseous state already at ground temperature. This gas then enters.

Cycle 2, compression

It is this compressor that consumes all the energy necessary for the operation of the heat pump, but compared, for example, with heating from, these costs are noticeably lower. We'll come back to cost comparisons later.

So, gaseous refrigerant heated to a temperature of 7-12°C from underground pipes in the compressor chamber is strongly compressed, which leads to its sharp heating. To understand this, just think about how hot a regular bicycle pump gets when you inflate your tires. The principle is the same.

Note to the owner

“The heat pump is modern heating. But the actual efficiency values ​​of heat pumps depend on temperature conditions, i.e. on cold days their effectiveness decreases. It is about 150% at a temperature of −20 °C, and about 300% at a source temperature of +7 °C.”

Cycle 3, condensation

After the compression cycle, we received hot steam under high pressure, which is supplied to the internal, “home” part of the heat pump. Now this gas can be used for an air heating system or for heating water in a water heating and hot water supply system. This hot steam can also be used with the "" system.

By releasing heat into the heating system, the hot gas cools, condenses and turns into liquid.

Cycle 4, expansion

This fluid enters the expansion valve, where its pressure is reduced. The low-pressure liquid refrigerant is now sent underground again to be heated to ground temperature. And all the cycles repeat.

Efficiency of heat pumps

For every 1 kW of electricity consumed by a heat pump to operate its compressor, on average, about 4 kW of useful thermal energy is generated. This corresponds to 300% efficiency.

Comparison of heating using a heat pump with other methods.

Data provided by the European Heat Pump Association (EHPA)

Heating type	Energy efficiency, %

Please understand that heat pump efficiency varies depending on the specific conditions in which your unit operates. So, if you are using a ground source heat pump and you have clay soil on your property, the efficiency of the heat pump will be approximately twice as high as if the heat pump pipes were in sandy soil.

It should also be remembered that the underground part should be laid below the freezing mark of the soil. Otherwise, the heat pump will not work at all.

The actual efficiency values ​​of heat pumps depend on temperature conditions, i.e. on cold days their effectiveness decreases. It is about 150% at a temperature of −20 °C, and about 300% at a source temperature of +7 °C. But technology does not stand still - modern models are more energy efficient, and this trend continues.

Heat pumps for home cooling

In terms of its operating principle, a heat pump is similar to or. Therefore, in the summer it can be used not for heating the house, but for cooling or air conditioning. Let us remember that if we are talking about an “earthen” heat pump, then the soil temperature is stable within 7-12°C all year round. And with the help of a heat pump it can be transferred to the premises of the house.

The principle of operation of a cooling system using a heat pump is similar to a heating system, only instead of radiators it is used. With passive cooling, the coolant simply circulates between the fan coils and the well, i.e. the cold from the well directly enters the air conditioning system, but the compressor itself does not work. If passive cooling is not enough, the heat pump compressor is turned on, which additionally cools the coolant.

Types of Heat Pumps

Household heat pumps come in 3 main types, differing in the external heat source:

• “earth” or “ground-water”, “ground-air”;
• “water” or “water-water”, “water-air”;
• "air" or "air-to-water", "air-to-air".

Ground source heat pumps

The most popular are heat pumps that use the heat of the earth. They have already been discussed above. These are the most effective, but also the most expensive of all types. Pipes going underground can be located vertically or horizontally. Depending on this, “ground” heat pumps are divided into vertical And horizontal.

Vertical heat pumps require immersion of pipes through which the refrigerant circulates to a considerable depth: 50-200 m. True, there is an alternative - to make not one such well, but several, but smaller ones. The distance between such wells must be at least 10 m. To calculate the drilling depth, you can roughly estimate that a 10 kW heat pump will require wells (one or more) with a total depth of about 170 m. It should also be remembered that it is useless to drill very shallow ones - less than 50 m - wells.

At horizontal laying expensive drilling to great depths is not required. The depth of laying pipelines with this method is about 1 m; depending on the region of installation, this value can either decrease or increase. With this method, the pipe with the refrigerant is laid so that the distance between adjacent sections is at least one and a half meters, otherwise heat collection is not effective.

Note to the owner

“If you live in a temperate climate zone - for example, in the North-West - then the most effective option for you is a heat pump that uses the heat of the earth. Moreover, it is better to install a vertical version of the heat pump - especially if your house is located on rocky rocks.”

To install a 10 kW heat pump, you need a total length of buried pipe of about 350-450 m. If you take into account the restrictions associated with the proximity of different areas to each other, then you will need a plot of land with dimensions of 20 by 20 meters. Whether such a free plot is available is a big question.

How to choose the right heat pump

If you live in a temperate climate zone - for example, in the Northwest - then the most effective option for you is a heat pump that uses the heat of the earth. Moreover, it is better to install a vertical version of the heat pump - especially if your house is located on rocky rocks, where finding a free vast plot of land is problematic. But this type of heat pump is the most expensive in terms of capital costs.

In an area with a mild climate - for example, in Sochi - you can install an air-to-water heat pump, which does not require excessive capital costs and is especially effective in areas where seasonal temperature fluctuations are relatively small.

Depending on the principle of operation, there are also. Models powered by electricity are more popular.

One more important note. A good idea is combined heat pump models that combine the classic version of a heat pump with a gas or electric heater. Such heaters can be used in adverse weather conditions when the efficiency of the heat pump is reduced. As already mentioned, a particularly low efficiency is typical for air-to-water and air-to-air heat pumps.

The combination of these two heat sources allows to reduce the cost of capital expenditures and increase the payback period of the heat pump installation.

Advantages and disadvantages of heat pumps

The main advantage of heat pumps is their low operating costs. Those. The cost of the heat or cooling produced to the end user is the lowest compared to other heating/air conditioning methods. In addition, a heat pump system is practically safe for the home. Consequently, the requirements for the ventilation systems of its premises are simplified and the level of fire safety is increased. Which also has a positive effect on the cost of installing these systems.

Heat pumps are easy to use and very reliable, and are also practically silent.

Another plus is that you can easily switch the heat pump from heating to cooling if necessary. You just need to have not only heating systems at home, but also fan coil units.

What is a heat pump for a home ✮Large selection of heat pumps on the website portal

But they also have disadvantages, the main one of which is the flip side of the main advantage - the capital costs of their installation are very significant. Until recently, another disadvantage of heat pumps was the relatively low temperature of the coolant - no more than 60 C. But recent developments have made it possible to eliminate this disadvantage. True, the price for such models is higher than for standard ones.

Paying for electricity and heating becomes more difficult every year. When building or purchasing a new home, the problem of economical energy supply becomes especially acute. Due to periodically recurring energy crises, it is more profitable to increase the initial costs of high-tech equipment in order to then receive heat at a minimal cost for decades.

The most cost-effective option in some cases is a heat pump for heating a home; the operating principle of this device is quite simple. It is impossible to pump heat in the literal sense of the word. But the law of conservation of energy allows technical devices to lower the temperature of a substance in one volume, while simultaneously heating something else.

What is a heat pump (HP)

Let's take an ordinary household refrigerator as an example. Inside the freezer, water quickly turns to ice. On the outside there is a radiator grille that is hot to the touch. From it, the heat collected inside the freezer is transferred to the room air.

The TN does the same thing, but in reverse order. The radiator grille, located on the outside of the building, is much larger in order to collect enough heat from the environment to heat the home. The coolant inside the radiator or manifold tubes transfers energy to the heating system inside the house and is then heated again outside the house.

Device

Providing heat to a home is a more complex technical task than cooling a small volume of a refrigerator where a compressor with freezing and radiator circuits is installed. The design of an air heat pump is almost as simple, it receives heat from the atmosphere and heats the internal air. Only fans are added to blow the circuits.

It is difficult to obtain a large economic effect from installing an air-to-air system due to the low specific gravity of atmospheric gases. One cubic meter of air weighs only 1.2 kg. Water is about 800 times heavier, so the calorific value also has a multiple difference. From 1 kW of electrical energy spent by an air-to-air device, only 2 kW of heat can be obtained, and a water-to-water heat pump provides 5–6 kW. TN can guarantee such a high coefficient of efficiency (efficiency).

Composition of pump components:

1. Home heating system, for which it is better to use heated floors.
2. Boiler for hot water supply.
3. A condenser that transfers energy collected externally to the indoor heating fluid.
4. An evaporator that takes energy from the coolant that circulates in the external circuit.
5. A compressor that pumps refrigerant from the evaporator, converting it from a gaseous to a liquid state, increasing the pressure and cooling it in the condenser.
6. An expansion valve is installed in front of the evaporator to regulate the refrigerant flow.
7. The outer contour is laid on the bottom of the reservoir, buried in trenches or lowered into wells. For air-to-air heat pumps, the circuit is an external radiator grille, blown by a fan.
8. Pumps pump coolant through pipes outside and inside the house.
9. Automation for control according to a given room heating program, which depends on changes in outside air temperature.

Inside the evaporator, the coolant of the external pipe register is cooled, giving off heat to the refrigerant of the compressor circuit, and then is pumped through the pipes at the bottom of the reservoir. There it heats up and the cycle repeats again. The condenser transfers heat to the cottage heating system.

Prices for different heat pump models

Heat pump

Principle of operation

The thermodynamic principle of heat transfer, discovered at the beginning of the 19th century by the French scientist Carnot, was later detailed by Lord Kelvin. But the practical benefits of their works devoted to solving the problem of heating housing from alternative sources have appeared only in the last fifty years.

In the early seventies of the last century, the first global energy crisis occurred. The search for economical heating methods has led to the creation of devices capable of collecting energy from the environment, concentrating it and directing it to heat the house.

As a result, a HP design was developed with several thermodynamic processes interacting with each other:

1. When the refrigerant from the compressor circuit enters the evaporator, the pressure and temperature of the freon drops almost instantly. The resulting temperature difference contributes to the extraction of thermal energy from the coolant of the external collector. This phase is called isothermal expansion.
2. Then adiabatic compression occurs - the compressor increases the pressure of the refrigerant. At the same time, its temperature rises to +70 °C.
3. Passing the condenser, freon becomes a liquid, since at increased pressure it gives off heat to the in-house heating circuit. This phase is called isothermal compression.
4. When the freon passes through the choke, the pressure and temperature drop sharply. Adiabatic expansion occurs.

Heating the internal volume of a room according to the HP principle is possible only with the use of high-tech equipment equipped with automation to control all of the above processes. In addition, programmable controllers regulate the intensity of heat generation according to fluctuations in outside air temperature.

Alternative fuel for pumps

There is no need to use carbon fuel in the form of firewood, coal, or gas to operate the HP. The source of energy is the heat of the planet scattered in the surrounding space, inside of which there is a constantly operating nuclear reactor.

The solid shell of continental plates floats on the surface of liquid hot magma. Sometimes it breaks out during volcanic eruptions. Near the volcanoes there are geothermal springs, where you can swim and sunbathe even in winter. A heat pump can collect energy almost anywhere.

To work with various sources of dissipated heat, there are several types of heat pumps:

1. "Air-to-air." Extracts energy from the atmosphere and heats the air masses indoors.
2. "Water-air". Heat is collected by an external circuit from the bottom of the reservoir for subsequent use in ventilation systems.
3. "Ground-water". Heat collection pipes are located horizontally underground below the freezing level, so that even in the most severe frost they can receive energy to heat the coolant in the heating system of the building.
4. "Water-water." The collector is laid out along the bottom of the reservoir at a depth of three meters, the collected heat heats the water circulating in the heated floors inside the house.

There is an option with an open external collector, when you can get by with two wells: one for collecting groundwater, and the second for draining back into the aquifer. This option is only possible if the quality of the liquid is good, because the filters quickly become clogged if the coolant contains too many hardness salts or suspended microparticles. Before installation, it is necessary to do a water analysis.

If a drilled well quickly silts up or the water contains a lot of hardness salts, then stable operation of the HP is ensured by drilling more holes in the ground. The loops of the sealed outer contour are lowered into them. Then the wells are plugged using plugging made from a mixture of clay and sand.

Using dredge pumps

You can extract additional benefit from areas occupied by lawns or flower beds using ground-to-water HP. To do this, you need to lay pipes in trenches to a depth below the freezing level to collect underground heat. The distance between parallel trenches is at least 1.5 m.

In the south of Russia, even in extremely cold winters, the ground freezes to a maximum of 0.5 m, so it is easier to completely remove the layer of earth at the installation site with a grader, lay the collector, and then fill the pit with an excavator. Shrubs and trees, whose roots can damage the external contour, should not be planted in this place.

The amount of heat received from each meter of pipe depends on the type of soil:

• dry sand, clay - 10–20 W/m;
• wet clay - 25 W/m;
• moistened sand and gravel - 35 W/m.

The area of ​​land adjacent to the house may not be sufficient to accommodate an external pipe register. Dry sandy soils do not provide sufficient heat flow. Then they use drilling wells up to 50 meters deep to reach the aquifer. U-shaped collector loops are lowered into the wells.

The greater the depth, the higher the thermal efficiency of the probes inside the wells increases. The temperature of the earth's interior increases by 3 degrees every 100 m. The efficiency of energy removal from a well collector can reach 50 W/m.

Installation and commissioning of HP systems is a technologically complex set of works that can only be performed by experienced specialists. The total cost of equipment and component materials is significantly higher when compared with conventional gas heating equipment. Therefore, the payback period for initial costs extends over years. But a house is built to last for decades, and geothermal heat pumps are the most profitable heating method for country cottages.

Annual savings compared to:

• gas boiler - 70%;
• electric heating - 350%;
• solid fuel boiler - 50%.

When calculating the payback period of a HP, it is worth taking into account the operating costs for the entire service life of the equipment - at least 30 years, then the savings will many times exceed the initial costs.

Water-to-water pumps

Almost anyone can place polyethylene collector pipes at the bottom of a nearby reservoir. This does not require much professional knowledge, skills, or tools. It is enough to evenly distribute the coils of the coil over the surface of the water. There must be a distance between the turns of at least 30 cm, and a flooding depth of at least 3 m. Then you need to tie the weights to the pipes so that they go to the bottom. Substandard brick or natural stone are quite suitable here.

Installing a water-to-water HP collector will require significantly less time and money than digging trenches or drilling wells. The cost of purchasing pipes will also be minimal, since heat removal during convective heat exchange in an aquatic environment reaches 80 W/m. The obvious benefit of using HP is that there is no need to burn carbon fuel to produce heat.

An alternative method of heating a home is becoming increasingly popular, as it has several more advantages:

1. Environmentally friendly.
2. Uses a renewable energy source.
3. After commissioning is completed, there are no regular costs of consumables.
4. Automatically adjusts the heating inside the house based on the outside temperature.
5. The payback period for initial costs is 5–10 years.
6. You can connect a boiler for hot water supply to the cottage.
7. In summer it works like an air conditioner, cooling the supply air.
8. The service life of the equipment is more than 30 years.
9. Minimum energy consumption - generates up to 6 kW of heat using 1 kW of electricity.
10. Complete independence of heating and air conditioning of the cottage in the presence of an electric generator of any type.
11. Adaptation to the “smart home” system for remote control and additional energy savings is possible.

To operate a water-to-water HP, three independent systems are required: external, internal and compressor circuits. They are combined into one circuit by heat exchangers in which various coolants circulate.

When designing a power supply system, it should be taken into account that pumping coolant through the external circuit consumes electricity. The longer the length of the pipes, bends, and turns, the less profitable the VT. The optimal distance from the house to the shore is 100 m. It can be extended by 25% by increasing the diameter of the collector pipes from 32 to 40 mm.

Air - split and mono

It is more profitable to use air HP in the southern regions, where the temperature rarely drops below 0 °C, but modern equipment can operate at -25 °C. Most often, split systems are installed, consisting of indoor and outdoor units. The external set consists of a fan blowing through the radiator grille, the internal set consists of a condenser heat exchanger and a compressor.

The design of split systems provides for reversible switching of operating modes using a valve. In winter, the external unit is a heat generator, and in summer, on the contrary, it releases it to the outside air, working like an air conditioner. Air heat pumps are characterized by extremely simple installation of the external unit.

Other benefits:

1. The high efficiency of the outdoor unit is ensured by the large heat exchange area of ​​the evaporator radiator grille.
2. Uninterrupted operation is possible at outdoor temperatures down to -25 °C.
3. The fan is located outside the room, so the noise level is within acceptable limits.
4. In summer, the split system works like an air conditioner.
5. The set temperature inside the room is automatically maintained.

When designing the heating of buildings located in regions with long and frosty winters, it is necessary to take into account the low efficiency of air heaters at subzero temperatures. For 1 kW of consumed electricity there is 1.5–2 kW of heat. Therefore, it is necessary to provide additional sources of heat supply.

The simplest installation of VT is possible when using monoblock systems. Only the coolant pipes go inside the room, and all other mechanisms are located outside in one housing. This design significantly increases the reliability of the equipment and also reduces noise to less than 35 dB - this is at the level of a normal conversation between two people.

When installing a pump is not cost-effective

It is almost impossible to find free plots of land in the city for the location of the external contour of a ground-to-water HP. It is easier to install an air source heat pump on the external wall of the building, which is especially beneficial in the southern regions. For colder areas with prolonged frosts, there is a possibility of icing of the external radiator grille of the split system.

High efficiency of HP is ensured if the following conditions are met:

1. The heated room must have insulated external enclosing structures. The maximum amount of heat loss cannot exceed 100 W/m2.
2. TN is able to work effectively only with an inertial low-temperature “warm floor” system.
3. In the northern regions, HP should be used in conjunction with additional heat sources.

When the outside air temperature drops sharply, the inertial circuit of the “warm floor” simply does not have time to warm up the room. This happens often in winter. During the day the sun was warm, the thermometer showed -5 °C. At night, the temperature can quickly drop to -15 ° C, and if a strong wind blows, the frost will be even stronger.

Then you need to install regular batteries under the windows and along the outer walls. But the temperature of the coolant in them should be twice as high as in the “warm floor” circuit. A fireplace with a water circuit can provide additional energy in a country cottage, and an electric boiler can provide additional energy in a city apartment.

It remains only to determine whether the HP will be the main or supplementary heat source. In the first case, it must compensate for 70% of the total heat loss of the room, and in the second - 30%.

Video

The video provides a visual comparison of the advantages and disadvantages of various types of heat pumps and explains in detail the structure of the air-water system.

Evgeniy AfanasyevChief Editor

Author of the publication 05.02.2019

Having refrigerators and air conditioners in their home, few people know that the principle of operation of a heat pump is implemented in them.

About 80% of the power produced by a heat pump comes from ambient heat in the form of diffuse solar radiation. It is this pump that simply “pumps” it from the street into the house. The operation of a heat pump is similar to the principle of operation of a refrigerator, but the direction of heat transfer is different.

Simply put…

To cool a bottle of mineral water, you place it in the refrigerator. The refrigerator must “take” part of the thermal energy from the bottle and, according to the law of conservation of energy, move it somewhere and give it away. The refrigerator transfers heat to a radiator, usually located on the rear wall. At the same time, the radiator heats up, releasing its heat into the room. In fact, it heats the room. This is especially noticeable in small minimarkets in the summer, when several refrigerators are turned on in the room.

We invite you to dream up your imagination. Let's assume that we will constantly put warm objects in the refrigerator, and by cooling them, it will heat the air in the room. Let's go to the “extremes”... Let's place the refrigerator in the window opening with the open “freezer” door facing outwards. The refrigerator radiator will be located indoors. During operation, the refrigerator will cool the air outside, transferring the “taken” heat into the room. This is how a heat pump works, taking dispersed heat from the environment and transferring it into the room.

Where does the pump get the heat?

The operating principle of a heat pump is based on the “exploitation” of natural low-potential heat sources from the environment.

They may be:

• just outside air;
• warmth of water bodies (lakes, seas, rivers);
• warmth of the soil, groundwater (thermal and artesian).

How does a heat pump and the heating system with it work?

The heat pump is integrated into the heating system, which consists of 2 circuits + a third circuit - the system of the pump itself. A non-freezing coolant circulates along the external circuit, which absorbs heat from the surrounding space.

Getting into the heat pump, or more precisely its evaporator, the coolant releases an average of 4 to 7 °C to the heat pump refrigerant. And its boiling point is -10 °C. As a result, the refrigerant boils and then transforms into a gaseous state. The coolant of the external circuit, already cooled, goes to the next “turn” in the system to set the temperature.

The functional circuit of the heat pump includes:

• evaporator;
• compressor (electric);
• capillary;
• capacitor;
• refrigerant;
• thermostatic control device.

The process looks something like this!

The refrigerant that has “boiled” in the evaporator is supplied through a pipeline to a compressor powered by electricity. This “hard worker” compresses the gaseous refrigerant to high pressure, which, accordingly, leads to an increase in its temperature.

The now hot gas then enters another heat exchanger, which is called a condenser. Here, the heat of the refrigerant is transferred to the room air or coolant, which circulates through the internal circuit of the heating system.

The refrigerant cools while simultaneously turning into a liquid. It then passes through the capillary pressure reducing valve, where it “loses” pressure and returns to the evaporator.

The cycle is closed and ready to repeat!

Approximate calculation of the heating output of the installation

Within an hour, up to 2.5-3 m 3 of coolant flows through the external collector through the pump, which the earth can heat by ∆t = 5-7 °C.

To calculate the thermal power of such a circuit, use the formula:

Q = (T_1 - T_2)*V_heat

V_heat - volumetric flow rate of coolant per hour (m^3/hour);

T_1 - T_2 - temperature difference between inlet and inlet (°C).

Types of heat pumps

Heat pumps are classified according to the type of dissipated heat used:

• ground-water (use closed ground contours or deep geothermal probes and a water heating system);
• water-water (they use open wells for the intake and discharge of groundwater - the external circuit is not looped, the internal heating system is water);
• water-air (use of external water circuits and an air-type heating system);
• (use of dissipated heat from external air masses complete with an air heating system for the house).

Advantages and benefits of heat pumps

Cost effective. The operating principle of a heat pump is based not on the production, but on the transfer (transportation) of thermal energy, so it can be argued that its efficiency is greater than one. What nonsense? - you say. The topic of heat pumps includes a value - the heat conversion coefficient (HCT). It is by this parameter that units of similar types are compared with each other. Its physical meaning is to show the ratio of the amount of heat received to the amount of energy expended for this. For example, with KPT = 4.8, the 1 kW of electricity expended by the pump will allow us to obtain 4.8 kW of heat free of charge, that is, free of charge from nature.

Universal ubiquity of application. Even in the absence of accessible power lines, the heat pump compressor can be powered by a diesel drive. And “natural” heat is available in every corner of the planet - the heat pump will not remain “hungry”.

Environmentally friendly use. There are no combustion products in the heat pump, and its low energy consumption “operates” power plants less, indirectly reducing harmful emissions from them. The refrigerant used in heat pumps is ozone-friendly and does not contain chlorocarbons.

Bidirectional operating mode. A heat pump can heat a room in winter and cool it in summer. The “heat” taken from the room can be used effectively, for example, to heat water in a swimming pool or in a hot water system.

Operational safety. In the principle of operation of a heat pump, you will not consider dangerous processes. The absence of open fire and harmful emissions that are dangerous to humans, and the low temperature of coolants make the heat pump a “harmless” but useful household appliance.

Some nuances of operation

Effective use of the heat pump operating principle requires compliance with several conditions:

• the room that is heated must be well insulated (heat loss up to 100 W/m2) - otherwise, taking heat from the street, you will heat the street at your own expense;
• Heat pumps are advantageous to use for low-temperature heating systems. Underfloor heating systems (35-40 °C) are ideal for such criteria. The heat conversion coefficient significantly depends on the temperature ratio of the input and output circuits.

Let's summarize what has been said!

The essence of the principle of operation of a heat pump is not in the production, but in the transfer of heat. This allows you to obtain a high coefficient (from 3 to 5) of thermal energy conversion. Simply put, every 1 kW of electricity used will “transfer” 3-5 kW of heat into the house. Anything else that needs to be said?