Heat pump for home heating: principle of operation, overview of models, their pros and cons. How to choose the right heat pump? What are home heating heat pumps

Any owner of a private house seeks to minimize the cost of heating the home. In this regard, heat pumps are significantly more profitable than other heating options, they provide 2.5-4.5 kW of heat per kilowatt of electricity consumed. The reverse side of the coin: to get cheap energy, you will have to invest a lot of money in equipment, the most modest heating installation with a capacity of 10 kW will cost 3500 USD. e. (starting price).

The only way to reduce costs by 2-3 times is to make a heat pump with your own hands (abbreviated as TN). Consider several real working options, collected and tested by enthusiastic craftsmen in practice. Since the manufacture of a complex unit requires basic knowledge of refrigeration machines, let's start with theory.

Features and principle of operation of HP

How does a heat pump differ from other installations for heating private houses:

unlike boilers and heaters, the unit does not produce heat on its own, but, like an air conditioner, moves it inside the building;
HP is called a pump, because it “pumps out” energy from sources of low-grade heat - ambient air, water or soil;
the unit is powered exclusively by electricity consumed by the compressor, fans, circulation pumps and control board;
the operation of the unit is based on the Carnot cycle used in all refrigeration machines, such as air conditioners and split systems.

In heating mode, a traditional split system works normally at temperatures above minus 5 degrees, in severe frost the efficiency drops sharply

Reference. Heat is contained in any substance whose temperature is above absolute zero (minus 273 degrees). Modern technologies make it possible to take the specified energy from air with a temperature of up to -30 ° C, earth and water - up to +2 ° C.

The Carnot heat exchange cycle involves the working fluid - freon gas, boiling at sub-zero temperatures. Alternately evaporating and condensing in two heat exchangers, the refrigerant absorbs the energy of the environment and transfers it inside the building. In general, the principle of operation of a heat pump repeats that included in heating:

Being in the liquid phase, freon moves through the tubes of the external evaporator heat exchanger, as shown in the diagram. Receiving the heat of air or water through the metal walls, the refrigerant heats up, boils and evaporates.
Then the gas enters the compressor, which pressurizes to the calculated value. Its task is to raise the boiling point of the substance so that the freon condenses at a higher temperature.
Passing through the internal heat exchanger-condenser, the gas again turns into a liquid and gives the accumulated energy to the heat carrier (water) or room air directly.
At the last stage, liquid freon enters the receiver-moisture separator, then into the throttling device. The pressure of the substance drops again, freon is ready to go through a second cycle.

The scheme of operation of a heat pump is similar to the principle of operation of a split system

Note. Conventional split systems and factory heat pumps have in common - the ability to transfer energy in both directions and operate in 2 modes - heating / cooling. Switching is implemented using a four-way reversing valve that changes the direction of gas flow along the circuit.

In domestic air conditioners and HP, various types of thermostatic valves are used to reduce the pressure of the refrigerant before the evaporator. In household split systems, a simple capillary device plays the role of a regulator; an expensive thermostatic expansion valve (TRV) is installed in pumps.

Note that the above cycle occurs in all types of heat pumps. The difference lies in the methods of heat supply / removal, which we will list below.

Types of throttle fittings: capillary tube (photo on the left) and thermostatic expansion valve (TRV)

Varieties of installations

According to the generally accepted classification, HPs are divided into types according to the source of energy received and the type of coolant to which it is transferred:

Reference. Varieties of heat pumps are listed in order of increasing cost of equipment along with installation. Air installations are the cheapest, geothermal installations are expensive.

The main parameter that characterizes a heat pump for heating a house is the efficiency coefficient COP, equal to the ratio between the energy received and the energy consumed. For example, relatively inexpensive air heaters cannot boast of high COP - 2.5 ... 3.5. We explain: having spent 1 kW of electricity, the installation supplies 2.5-3.5 kW of heat to the dwelling.

Methods for extracting heat from water sources: from a pond (left) and through wells (right)

Water and soil systems are more efficient, their real coefficient lies in the range of 3…4.5. Performance is a variable value that depends on many factors: the design of the heat exchange circuit, immersion depth, temperature and water flow.

An important point. Hot water heat pumps are not able to heat the coolant up to 60-90 °C without additional circuits. The normal water temperature from the HP is 35 ... 40 degrees, the boilers clearly win here. Hence the recommendation of the manufacturers: connect the equipment to low-temperature heating - water.

Which TN is better to collect

We formulate the problem: you need to build a home-made heat pump at the lowest cost. A number of logical conclusions follow from this:

The installation will have to use a minimum of expensive parts, so it will not be possible to achieve a high COP value. In terms of performance, our device will lose to factory models.
Accordingly, it is pointless to make a pure air HP, it is easier to use it in heating mode.
To get real benefits, you need to make an air-to-water, water-to-water heat pump or build a geothermal installation. In the first case, you can achieve a COP of about 2-2.2, in the rest - reach an indicator of 3-3.5.
It will not be possible to do without floor heating circuits. A coolant heated to 30-35 degrees is incompatible with a radiator network, except in the southern regions.

Laying the external contour of the HP to the reservoir

Comment. Manufacturers claim: the inverter split system operates at a street temperature of minus 15-30 ° C. In reality, the heating efficiency is significantly reduced. According to homeowners, on frosty days, the indoor unit delivers a barely warm air flow.

To implement the water version of the HP, certain conditions are required (optional):

a reservoir 25-50 m from the dwelling, at a greater distance, electricity consumption will increase dramatically due to a powerful circulation pump;
a well or well with a sufficient supply (debit) of water and a place for draining (pit, second well, gutter, sewerage);
prefabricated sewer (if you are allowed to crash into it).

Groundwater flow is easy to calculate. In the process of taking heat, a home-made HP will lower their temperature by 4-5 ° C, from here the volume of the flow is determined through the heat capacity of water. To obtain 1 kW of heat (we take a delta of water temperatures of 5 degrees), you need to drive about 170 liters through a heat pump for an hour.

Heating a house with an area of 100 m² will require a power of 10 kW and a water consumption of 1.7 tons per hour - an impressive volume. Such a thermal water pump is suitable for a small country house of 30-40 m², preferably insulated.

Methods of heat extraction by geothermal heat pumps

The assembly of a geothermal system is more realistic, although the process is quite laborious. The option of laying the pipe horizontally over an area at a depth of 1.5 m is immediately dismissed - you will have to shovel the entire area or pay money for the services of earthmoving equipment. The method of drilling wells is much easier and cheaper to implement, with virtually no disturbance to the landscape.

The simplest heat pump from a window air conditioner

As you might guess, for the manufacture of a water-to-air heat pump, a window cooler in working condition is required. It is highly desirable to buy a model equipped with a reversing valve and able to work for heating, otherwise you will have to redo the freon circuit.

Advice. When buying a used air conditioner, pay attention to the nameplate, which displays the technical characteristics of the household appliance. The parameter you are interested in is (indicated in kilowatts or British thermal units - BTU).

The heating capacity of the device is greater than the refrigeration one and is equal to the sum of two parameters - the performance plus the heat generated by the compressor

With some luck, you don't even have to release freon and re-solder the tubes. How to convert an air conditioner into a heat pump:

Recommendation. If the heat exchanger cannot be placed in the tank without breaking the freon lines, try to evacuate the gas and cut the pipes at the right points (away from the evaporator). After assembling the water heat exchange unit, the circuit will have to be soldered and filled with freon. The amount of refrigerant is also indicated on the label.

Now it remains to start a home-made HP and adjust the water flow, achieving maximum efficiency. Please note: the improvised heater uses a completely factory "stuffing", you just moved the radiator from the air to the liquid. How the system works live, look at the video of the craftsman:

Making a geothermal installation

If the previous option allows you to achieve approximately double savings, then even a home-made earth circuit will give a COP in the region of 3 (three kilowatts of heat per 1 kW of electricity consumed). True, financial and labor costs will also increase significantly.

Although a lot of examples of assembling such devices have been published on the Internet, there is no universal instruction with drawings. We will offer a working version, assembled and tested by a real home master, although many things will have to be thought out and completed on our own - it is difficult to put all the information about heat pumps in one publication.

Calculation of the ground circuit and pump heat exchangers

Following our own recommendations, we proceed to the calculations of a geothermal pump with vertical U-shaped probes placed in wells. It is necessary to find out the total length of the outer contour, and then - the depth and number of vertical shafts.

Initial data for the example: you need to heat a private insulated house with an area of 80 m² and a ceiling height of 2.8 m, located in the middle lane. we will not produce for heating, we will determine the need for heat by area, taking into account thermal insulation - 7 kW.

Optionally, you can equip a horizontal collector, but then you will have to allocate a large area for excavation

An important clarification. Engineering calculations of heat pumps are quite complex and require high qualifications of the performer; entire books are devoted to this topic. The article provides simplified calculations taken from the practical experience of builders and craftsmen - lovers of homemade products.

The intensity of heat exchange between the ground and the non-freezing liquid circulating along the contour depends on the type of soil:

1 running meter of a vertical probe immersed in groundwater will receive about 80 W of heat;
in stony soils, heat removal will be about 70 W / m;
clay soils saturated with moisture will give off about 50 W per 1 m of collector;
dry rocks - 20 W / m.

Reference. The vertical probe consists of 2 loops of pipes lowered to the bottom of the well and filled with concrete.

An example of calculating the length of a pipe. To extract the required 7 kW of thermal energy from the raw clay rock, you need to divide 7000 W by 50 W / m, we get a total probe depth of 140 m. Now the pipeline is distributed over wells 20 m deep, which you can drill with your own hands. A total of 7 drillings of 2 heat exchange loops, the total length of the pipe is 7 x 20 x 4 = 560 m.

The next step is to calculate the heat exchange area of the evaporator and condenser. Various Internet resources and forums offer some calculation formulas, in most cases they are incorrect. We will not take the liberty of recommending such methods and misleading you, but we will offer some tricky option:

Contact any well-known manufacturer of plate heat exchangers, such as Alfa Laval, Kaori, Anvitek, and so on. You can go to the official website of the brand.
Fill out the heat exchanger selection form or call the manager and order the selection of the unit, listing the parameters of the media (antifreeze, freon) - inlet and outlet temperature, heat load.
The company's specialist will make the necessary calculations and offer a suitable model of the heat exchanger. Among its characteristics you will find the main one - the exchange surface area.

Plate units are very efficient, but expensive (200-500 euros). It is cheaper to assemble a shell-and-tube heat exchanger from a copper tube with an outer diameter of 9.5 or 12.7 mm. Multiply the figure issued by the manufacturer by a safety factor of 1.1 and divide by the circumference of the pipe, get the footage.

A stainless steel plate heat exchanger is an ideal evaporator option, it is efficient and takes up little space. The problem is the high price of the product

Example. The heat exchange area of the proposed unit was 0.9 m². Choosing a copper tube ½ "with a diameter of 12.7 mm, we calculate the circumference in meters: 12.7 x 3.14 / 1000 ≈ 0.04 m. Determine the total footage: 0.9 x 1.1 / 0.04 ≈ 25 m.

Equipment and materials

The future heat pump is proposed to be built on the basis of an outdoor unit of a split system of suitable capacity (indicated on the plate). Why is it better to use a used air conditioner:

the device is already equipped with all components - a compressor, a throttle, a receiver and a starting electrician;
home-made heat exchangers can be placed in the body of the refrigeration machine;
there are convenient service ports for refueling freon.

Note. Users versed in the topic select equipment separately - compressor, expansion valve, controller, and so on. If you have experience and knowledge, such an approach is only welcome.

It is not advisable to assemble a heat pump on the basis of an old refrigerator - the power of the unit is too low. In the best case, it will be possible to “squeeze out” up to 1 kW of heat, which is enough to heat one small room.

In addition to the external "split" block, you will need the following materials:

HDPE pipe Ø20 mm - to the earth circuit;
polyethylene fittings for assembly of collectors and connection to heat exchangers;
circulation pumps - 2 pcs.;
manometers, thermometers;
high-quality water hose or HDPE pipe with a diameter of 25-32 mm for the shell of the evaporator and condenser;
copper tube Ø9.5-12.7 mm with a wall thickness of at least 1 mm;
insulation for pipelines and freon lines;
kit for sealing heating cables laid inside the water supply system (needed to seal the ends of copper pipes).

Bushing kit for sealed entry of copper tube

As an external coolant, a saline solution of water or antifreeze for heating - ethylene glycol is used. You will also need a supply of freon, whose brand is indicated on the nameplate of the split system.

Assembly of the heat exchanger

Before starting installation work, the outdoor module must be disassembled - remove all covers, remove the fan and a large regular radiator. Disable the solenoid that controls the reversing valve if you do not plan to use the pump as a coolant. Temperature and pressure sensors must be retained.

Assembly order of the main HP unit:

Fabricate the condenser and evaporator by inserting a copper tube inside the estimated length of the hose. At the ends, install tees for connecting the ground and heating circuits, seal the protruding copper pipes with a special heating cable kit.
Using a piece of plastic pipe Ø150-250 mm as a core, wind home-made two-pipe circuits and bring the ends in the right direction, as is done in the video below.
Place and fix both shell-and-tube heat exchangers in place of the standard radiator, solder the copper tubes to the corresponding terminals. A "hot" heat exchanger-condenser is best connected to the service ports.
Install factory sensors that measure the temperature of the refrigerant. Insulate the bare sections of the tubes and the heat exchangers themselves.
Install thermometers and pressure gauges on water lines.

Advice. If you plan to install the main unit outdoors, you need to take measures to prevent the oil in the compressor from freezing. Purchase and install a winter kit for electric oil sump heating.

On thematic forums, there is another way to make an evaporator - a copper tube is wound in a spiral, then inserted into a closed container (tank or barrel). The option is quite reasonable with a large number of turns, when the calculated heat exchanger simply does not fit in the air conditioner housing.

Ground loop device

At this stage, simple but time-consuming earthworks and the placement of probes in wells are carried out. The latter can be done manually or invite a drilling machine. The distance between adjacent wells is at least 5 m. Further work procedure:

Dig a shallow trench between the holes for laying the supply pipes.
Lower 2 loops of polyethylene pipes into each hole and fill the pits with concrete.
Bring the lines to the connection point and mount the common manifold using HDPE fittings.
Insulate pipelines laid in the ground and cover with soil.

On the left in the photo - lowering the probe into the casing plastic pipe, on the right - laying eyeliners in the trench

An important point. Before concreting and backfilling, be sure to check the tightness of the circuit. For example, connect an air compressor to the manifold, pressurize 3-4 bar and leave for several hours.

When connecting the highways, be guided by the diagram below. Branches with taps will be needed when filling the system with brine or ethylene glycol. Bring the two main pipes from the collector to the heat pump and connect to the “cold” evaporator heat exchanger.

At the highest points of both water circuits, air vents must be installed; they are not conventionally shown in the diagram

Do not forget to install the pumping unit responsible for the circulation of the liquid, the direction of flow is towards the freon in the evaporator. The media passing through the condenser and evaporator must move towards each other. How to properly fill the lines of the "cold" side, see the video:

Similarly, the condenser is connected to the house floor heating system. It is not necessary to install a mixing unit with a three-way valve due to the low flow temperature. If it is necessary to combine the HP with other heat sources (solar collectors, boilers), use multiple outputs.

Filling and starting the system

After installation and connection of the unit to the mains, an important stage begins - filling the system with refrigerant. A pitfall awaits here: you don’t know how much freon needs to be charged, because the volume of the main circuit has grown significantly due to the installation of a home-made condenser with an evaporator.

The issue is solved by the method of refueling according to the pressure and temperature of freon overheating, measured at the compressor inlet (the freon is supplied there in a gaseous state). Detailed instructions for filling in the temperature measurement method are set out in.

The second part of the presented video tells how to fill the system with R22 brand freon according to the pressure and temperature of the refrigerant superheat:

After refueling, turn on both circulation pumps to the first speed and start the compressor. Control the temperature of the brine and the internal coolant using thermometers. During the warm-up phase, the refrigerant lines may freeze, and then the frost should melt.

Conclusion

Making and running a geothermal heat pump with your own hands is very difficult. Surely, repeated improvements, bug fixes, tweaks will be required. As a rule, most malfunctions in home-made HPs occur due to improper assembly or filling of the main heat exchange circuit. If the unit immediately failed (safety automatics worked) or the coolant does not heat up, it is worth calling the refrigeration technician - he will diagnose and point out the mistakes made.

Since ancient times, mankind has been "accustomed" to using available natural resources. energy carriers, which are simply burned to produce heat or to be converted into other forms of energy. People also learned to use the hidden potential of water flows - they started from water mills and reached powerful hydroelectric power plants. However, what seemed quite sufficient a hundred years ago, today can no longer satisfy the needs of the growing population of the Earth.

Firstly, natural "pantries" are still not bottomless, and energy production is becoming more and more difficult every year, moving to hard-to-reach regions or even to sea shelves. Secondly, the combustion of natural raw materials is always associated with emissions of combustion products into the atmosphere, which, with the current huge volumes of such emissions, has already put the planet on the brink of an ecological disaster. The energy of hydroelectric power plants is not enough, and the violation of the hydrological balance of rivers also entails a lot of negative consequences. Nuclear power, which was once viewed as a "panacea", after a number of high-profile man-made disasters raises a lot of questions, and in many regions of the planet, the construction of nuclear power plants is simply prohibited by law.

However, there are other, almost inexhaustible sources of energy that have become widely used relatively recently. Modern technologies have made it possible to very effectively use the energy of wind, sunlight, ocean tides, etc. to produce electricity or heat. One of the alternative sources is the thermal energy of the earth's interior, water bodies, and the atmosphere. It is on the use of such sources that the operation of heat pumps is based. Such equipment for us is still included in the category of "exotic novelties", and at the same time, many Europeans heat their homes in this way - for example, in Switzerland or Scandinavian countries, the number of houses with such systems has exceeded 50%. Gradually, this type of heat generation is beginning to be practiced in Russian open spaces, although the prices for acquiring a high-tech set of equipment still look very frightening. But, as always, there are master enthusiasts who show their creativity and assemble heat pumps with their own hands.

The publication is aimed at ensuring that the reader can take a closer look at the principle of operation and the basic device of heat pumps, learn about their advantages and disadvantages. In addition, we will talk about successful experiences in creating existing installations on our own.

How a heat pump works

Not everyone thought about it, but around us there are many heat sources that “work” all year round and around the clock. For example, even in the most severe cold, the temperature under the ice of a frozen reservoir still remains positive. The same picture and when deepening into the thickness of the soil - below the border of its freezing, the temperature is almost always stable and approximately equal to the average annual characteristic for this region. The air also carries a considerable thermal potential.

Perhaps someone will be confused by the seemingly low temperatures of water, soil or air. Yes, they belong to low-potential energy sources, but their main “trump card” is stability, and modern technologies based on the laws of thermal physics allow even a slight difference to be converted into the necessary heating. Yes, and, you see, when the frost is 20 degrees outside in winter, and the soil has 5 ÷ 7 degrees below the freezing level, then such an amplitude difference is already quite decent.

It is this property of the continuity of the supply of low-potential energy that is embedded in the heat pump circuit. In fact, this unit is a device that "pumps" and "concerts" the heat taken from an inexhaustible source.

You can draw some analogy with the familiar refrigerator. The products that are placed in it for cooling and storage and the air entering the chamber when the door is opened are also not too hot. But if you touch the condenser heat exchange grate on the back wall of the refrigerator, then it is either very warm or even hot.

The prototype of a heat pump is a refrigerator familiar to everyone, the condenser grate of which heats up during operation.

So why not use this principle to heat the coolant? Of course, the analogy with the refrigerator is not direct - there is no stable external heat source, and electricity is mostly wasted. But in the case of a heat pump, such a source can be found (arranged), and then it will turn out to be a "reverse refrigerator" - the main focus of the unit will be precisely on obtaining heat.

On what principle does it work?

It is a system of three circuits with coolants circulating through them.

In the heat pump housing itself (pos. 1) there are two heat exchangers (pos. 4 and 8), a compressor (pos. 7), a refrigerant circuit (pos. 5), adjustment and control devices.
The first circuit (pos. 1) with its own circulation pump (pos. 2) is placed ( immersed) in a source of low-grade heat (their device will be discussed below). Receiving thermal energy from an external uninterruptible source (shown by a wide pink arrow), heated by only a few degrees (usually, when using probes or collectors in the ground or in water - up to 4 ÷ 6 ° WITH), the circulating coolant enters evaporator heat exchanger(pos. 4). Here, the primary transfer of heat received from the outside takes place.
The refrigerant used in the internal pump circuit (pos. 5) has an extremely low boiling point. Usually, one of the modern, environmentally friendly freons, or carbon dioxide (essentially liquefied carbon dioxide) is used here. It enters the evaporator inlet (pos. 6) in a liquid state, at reduced pressure - this provides an adjustable throttle (pos. 10). The special shape of the capillary inlet and the shape of the evaporator contribute to the almost instantaneous transition of the refrigerant to a gaseous state. According to the laws of physics, evaporation is always accompanied by a sharp cooling and absorption of ambient heat. Since this section of the internal circuit is located in the same heat exchanger with the primary circuit, freon takes thermal energy from the coolant, while cooling it (wide orange arrow). The cooled coolant continues to circulate and again gains thermal energy from an external source.
The refrigerant, already in a gaseous state, transferring the heat transferred to it, enters the compressor (pos. 7), where, under the influence of compression, its temperature rises sharply. Further, it enters the next heat exchanger (pos. 8), in which the condenser and pipes of the third circuit of the heat pump are located. (pos. 11).
Here, a completely opposite process occurs - the refrigerant condenses, turning into a liquid state, while giving up its heat to the third circuit coolant. Further, in a liquid state at high pressure, it passes through a throttle, where the pressure decreases, and the cycle of physical transformations of the aggregate state of the refrigerant is repeated again and again.
Now goes to the third circuit (pos. 11) of the heat pump. Through the heat exchanger (pos. 8), thermal energy is transferred to it from the refrigerant heated by compression (wide red arrow). This circuit has its own circulation pump (pos. 12), which ensures the movement of the coolant through the heating pipes. However, it is much more reasonable to use an accumulating, carefully insulated buffer tank (pos. 13), in which the transferred heat will accumulate. The accumulated supply of thermal energy is already spent for the needs of heating and hot water supply, being spent gradually, as needed. Such a measure allows you to insure against power outages or use a cheaper nightly tariff for the electricity needed to operate the heat pump.

If a buffer storage tank is installed, then a heating circuit (pos. 14) with its own circulation pump (pos. 15) is already connected to it, ensuring the movement of the coolant through the system pipes (pos. 16). As already mentioned, there may be a second circuit, which provides hot water for domestic needs.

The heat pump cannot work without electricity - it is required for the operation of the compressor (wide green arrow), and the circulation pumps in the external circuits also consume electricity. However, as the developers and manufacturers of heat pumps assure, the consumption of electricity is incomparable with the received “volume” of thermal energy. So, with proper assembly and optimal operating conditions, there is often talk of 300 percent or more efficiency, that is, with one kilowatt of electricity spent, a heat pump can produce 4 kilowatts of thermal energy.

In fact, such a statement about efficiency is somewhat incorrect. Nobody canceled the laws of physics, and efficiency above 100% is the same utopia as " perpetummobile"- perpetual motion machine. In this case, we are talking about the rational use of electricity for the purpose of "pumping" and converting energy coming from an inexhaustible external source. Here it is more appropriate to use the concept of COP (from the English "coefficient of performance") which in Russian is often called the “heat conversion coefficient”. In this case, indeed, values \u200b\u200bthat exceed one can turn out:

CO R = Qn / a, Where:

CO R is the coefficient of heat conversion;

QP- the amount of thermal energy received by the consumer;

A- the work performed by the compressor unit.

There is one more nuance that is often simply forgotten - not only the compressor, but also circulation pumps in external circuits require a certain amount of energy for the normal functioning of the pump. Their power consumption, of course, is much less, but, nevertheless, it can also be taken into account, and this is often simply not done for marketing purposes.

The total amount of thermal energy received can be spent:

1 - the optimal solution is a system of warm water floors. As a rule, heat pumps give a "rise" in temperature to a level of about 50 ÷ 60 ° WITH- this is enough for underfloor heating.

2 - domestic hot water supply. Usually in DHW systems, the temperature is maintained at this level - about 45 ÷ 55 ° С.

3 - but for conventional radiators, such heating will be clearly not enough. The way out is to increase the number of sections or use special low-temperature radiators. Convection type heaters will also help to solve the issue.

4 - one of the most important advantages of heat pumps is the ability to switch them to the "opposite" mode of operation. In the summer, such a unit can perform the function of air conditioning - taking heat from the premises and transferring it to the ground or a reservoir.

Sources of low-potential energy

What sources of low-potential energy are capable of using heat pumps? This role can be played by rocks, soil at different depths, water from natural reservoirs, or underground aquifers, atmospheric air or warm air streams removed from buildings or from industrial technological complexes.

A. Use of thermal energy soils

As already mentioned, below the level of soil freezing characteristic of this region, the soil temperature is stable throughout the year. This is what is used for the operation of heat pumps according to the "soil - water" scheme.

Schematic diagram of the extraction of energy "soil - water"

To create such a system, special surface thermal fields are being prepared, on which the upper layers of soil are removed to a depth of about 1.2 ÷ 1, 5 meters. They contain contours made of plastic or metal-plastic pipes with a diameter, as a rule, of 40 mm. The efficiency of heat energy removal depends on local climatic conditions and on the total length of the circuit being created.

Tentatively, for central Russia, you can operate with the following ratios:

Dry sandy soils - 10 W of energy per linear meter of pipe.
Dry clay soils - 20 W / m.
Wet clay soils - 25 W / m.
Clay rock with a high location of groundwater - 35 W / m.

Despite the apparent simplicity of such heat transfer, the method is by no means always the optimal solution. The fact is that it involves a very significant amount of earthwork. What looks simple in a diagram is much more difficult in practice. Judge for yourself - in order to "remove" even only 10 kWt of thermal energy from the underground circuit on clay soil, about 400 meters of pipe will be required. If we also take into account the mandatory rule that between the turns of the circuit there must be an interval of at least 1, 2 meters, then for laying a plot of 4 acres (20 × 20 meters) will be required.

Establishing a field for extracting heat from the ground is an extremely large-scale and time-consuming task.

First, not everyone has the opportunity to allocate such a territory. Secondly, any buildings are completely excluded in this area, since there is a high probability of damage to the circuit. And thirdly, the extraction of heat from the soil, especially with poor-quality calculations, may not pass without a trace. The effect of overcooling of the site is not excluded, when summer heat cannot fully restore the temperature balance at the depth of the contour. This can negatively affect the biological balance in the surface layers of the soil, and as a result, some plants simply will not grow in a supercooled area - such a kind of local effect of the "ice age".

B. Thermal energy from wells

Even the small size of the site will not be an obstacle to organizing the care of thermal energy from a drilled well.

As a source of low-grade heat - a deep well

The temperature of the soil with increasing depth only becomes more stable, and at depths of more than 15 — 20 meters is firmly on the 10-degree mark, increasing by two ÷ three degrees for every 100 m of diving. Moreover, this value is absolutely independent of the time of year or the vagaries of the weather, which makes the well the most stable and predictable source of heat.

A probe is lowered into the wells, which is a U-shaped loop of plastic (metal-plastic) pipes with a coolant circulating through them. Most often, several wells are made with a depth of 40 ÷ 50 and up to 150 meters, no closer than 6 m from one another, which are connected either in series or with a connection to a common collector. The heat transfer of the soil with this arrangement of pipes is much higher:

With dry sedimentary rocks - 20 W / m.
Rocky soil layers or water-saturated sedimentary rocks - 50 W / m.
Solid rocks with high thermal conductivity - 70 W / m.
If you are lucky, and you get an underground aquifer - about 80 W / m.

In case of insufficient space or difficulties in deep drilling due to the characteristics of the soil, several inclined wells can be performed with beams from one point.

By the way, in the event that the well falls on an aquifer with a stable debit, then an open primary heat exchange circuit is sometimes used. In this case, water is pumped from a depth by a pump, participates in heat exchange, and then, cooled, is discharged into a second well of the same horizon, to located oncertain distance from the first (this is calculated when designing the system). At the same time, water intake for domestic needs can be organized.

The main disadvantage of the downhole method of heat extraction is the high cost of drilling, which is very difficult or simply impossible to carry out on our own without the appropriate equipment. In addition, well drilling often requires permits from environmental authorities. By the way, the use of direct heat exchange with reverse water discharge into the well may also be prohibited.

Can you drill a well yourself?

Of course, this is an extremely difficult task, but there are technologies that allow, under certain conditions, to perform it independently.

About how you can - in a special publication of our portal.

B. Use of water bodies as heat sources

A reservoir of sufficient depth located near the house may well become a good source of thermal energy. Water, even in winter, under the upper crust of ice remains in a liquid state, and its temperature is above zero - this is what the heat pump needs.

Approximate heat transfer from a circuit immersed in water is 30 kW / m. This means that in order to get a return of 10 kW, a circuit of the order of 350 m is required.

Such collector circuits are mounted on land from plastic pipes. Then they move into the pond and dive to the bottom, to the depths not less than 2 meters, for which loads are attached at the rate of 5 kg per 1 linear meter of pipe.

Then it executes thermally insulated laying pipes to the house and connecting them to thermal heat exchanger pump.

However, one should not think that any body of water is fully suitable for such purposes - again, very complex heat engineering calculations will be needed. For example, a small and not deep enough pond or a small, quiet stream, not only can they not cope with the task of uninterrupted supply of low-potential energy - they can simply be completely frozen to the bottom, thereby killing all the inhabitants of the reservoir.

Advantages of water heat sources - there is no need for drilling, earthworks are also reduced to a minimum - only digging trenches to the house for laying pipes. And as a disadvantage, low accessibility for most homeowners can be noted simply due to the lack of water bodies in reasonable proximity to housing.

By the way, for the purpose of heat exchange, drains are often used - they have a fairly stabilized positive temperature even in cold weather.

D. Taking heat from the air

Heat for heating a home or for hot water supply can be taken literally from the air. Air-to-water heat pumps operate on this principle. air – air».

By and large, this is the same air conditioner, only switched to the “winter” mode. The efficiency of such a heating system depends very much on the climatic conditions of the region, and on the vagaries of the weather. Although modern installations are designed to operate even at very low temperatures (up to -25, and some even up to -40 ° WITH), but the energy conversion coefficient drops sharply, the profitability and expediency of such an approach immediately begin to raise a lot of questions.

But on the other hand, such a heat pump does not require any labor-intensive operations at all - most often its primary heat exchange unit is installed either on the wall (roof) of the building, or in its immediate vicinity. By the way, it is almost impossible to distinguish it from the external unit of a split air conditioning system.

Such heat pumps are often used as additional sources of thermal energy for heating, and in the summer as a heat generator for hot water supply.

The use of such heat pumps is fully justified for recovery - the use of secondary heat, for example, at the outlets of ventilation shafts (ducts). Thus, the installation receives a fairly stable and high-temperature source of energy - this is widely used in industrial enterprises, where there are constantly sources of secondary heat for its disposal.

In air-to-air and air-to-water systems, there is no primary heat exchange circuit at all. The fans create an air stream that directly blows the evaporator tubes with the refrigerant circulating through them.

By the way, there is a whole line of heat pumps DX - type (from the English "direct exchange", which means "direct exchange"). In them, too, in fact, there is no primary circuit. Heat exchange with a source of low-grade heat (in wells or V layer of soil) passes immediately in copper pipes filled with refrigerant. On the one hand, this is more expensive and more difficult to implement, but it allows you to significantly reduce both the depth of the wells (one 30-meter vertical one or several inclined ones up to 15 m is enough), and the total area of the heat-exchange horizontal field, if it is located under the top layer of soil. Accordingly, we can talk about a greater conversion factor, and in general - the efficiency of the heat pump. But only copper heat exchange pipes are much more expensive than plastic ones and more difficult to install, and the cost of the refrigerant is much higher than that of a conventional antifreeze coolant.

And how is the air conditioner arranged, and can it be mounted independently?

It has already been said that basic principle the actions of the air conditioner and the heat pump are practically “twins”, but in a “mirror image”.

More about the device and the basic rules - in a special publication of the portal.

Video: useful information on the theory and practice of using heat pumps

General advantages and disadvantages of heat pumps

So, we can draw a certain line in the consideration of heat pumps, focusing on their main, imaginary and real, advantages and disadvantages.

A. High efficiency and overall profitability of this type of heating.

This has already been mentioned above - in a well-thought-out and properly installed system, under optimal operating conditions, you can count on receiving 4 kW of thermal energy instead of the spent 1 kW of electrical energy.

All this will be fair only if the housing has received the highest quality insulation. This, of course, applies to any heating systems, it’s just that these “magic numbers” of 300% show the importance of reliable thermal insulation to a greater extent.

In terms of regular costs for consumed energy resources, heat pumps are in first place in terms of efficiency, somewhat ahead of even cheap network gas. At the same time, one should also take into account the fact that there is no need to transport and store fuel reserves - if we are talking about stakes on solid or liquid fuel.

B. The heat pump can become highly economical main source of heating and hot water.

This issue has also already been touched upon. If the house is used as the main source of heating in the premises, then the heat pump of the appropriate power must “pull” such a load. For most of the usual radiators, a temperature of 50 ÷ 55 degrees will be clearly insufficient.

Special mention should be made of pumps that extract heat from the air. They are extremely sensitive to current weather conditions. Although manufacturers claim the possibility of working at -25 and even -40 ° WITH, efficiency drops sharply, and there can be no talk of any 300%.

A reasonable solution is to create a combined heating system (bivalent). As long as the HP has enough power, it acts as the main source of heat, in case of insufficient poweroffensive real cold weather - electric heating, liquid or solid fuel boiler, solar collector, etc. come to the rescue. Gas equipment is not considered in this case - if it is possible to use network gas for heating, then the need for a heat pump looks very doubtful, at least at the current level of energy prices.

IN. A heat pump heating system does not require a chimney. It works almost silently.

Indeed, the owners will not have any difficulties with the arrangement of the chimney. As for the silence of work, like any other household appliances with various drives, the noise background is still present - from the operation of the compressor, circulation pumps. Another question is that in modern models this noise level, with the correct debugging of the unit, is very small and does not cause concern to residents. In addition, probably, few people would think of installing such equipment in living rooms.

G. Full environmental friendliness of the system - there are no any emissions into the atmosphere, there is no threat to the residents of the house.

That's right, especially with regard to models in which modern freon, harmless to the ozone layer, is used as a refrigerant (for example, R-410A).

You can also immediately mark the fire - and explosion safety such a system - there are no flammable or combustible substances, the accumulation of their explosive concentrations is excluded.

D. Modern heat pumps are universal climate units capable of operating both for heating and air conditioning in the summer.

This is a very important advantage, which, indeed, gives the hosts a lot of additional amenities.

E. The operation of the heat pump is fully controlled by automation and does not require user intervention. Such a system, unlike others, does not need regular maintenance and preventive maintenance.

We can fully agree with the first statement, however, not forgetting to mention that most modern heating gas or electric installations are also fully automated, that is, not only heat pumps have this advantage.

But on the second question, you can enter into a discussion. Probably, none of the industrial or domestic heating units can do without regular checks and preventive maintenance. Even if it is fair to assume that it is not worth climbing into the internal circuit with a refrigerant and into automation, the external circuits with antifreeze or other coolant will still require some participation. Here and regular cleaning (especially in air systems), and monitoring the composition and level of the coolant, and auditing the operation of circulation pumps, and checking the condition of the pipes for integrity and the presence of leaks on the fittings, and much more - in a word, something that cannot be done without one heating system. In a word, the statement about the complete uselessness of maintenance looks, at least, unfounded.

AND. Fast payback of a heating system with a heat pump.

This question is so ambiguous that it deserves special attention.

Some companies involved in the implementation of such equipment promise their potential customers a very quick return on investment in the implementation of the project. They give calculations in tables, according to which, indeed, one can create an opinion that a heat pump is the only acceptable solution if it is not possible to stretch a gas main to the house.

Here is one such sample:

Fuel types	Natural gas (methane)	Firewood chopped birch	Email energy at a single rate	Diesel fuel	Heat pump (night rate)
Unit fuel supplies	m³	3 m³	kWh	liter	kWh
Fuel cost. with delivery, rub	5.95	6000	3.61	36.75	0.98
fuel calorie content	38.2	4050	1	36	1
Unit calorie measurements	MJ/m³	kWh	kWh	MJ/liter	kWh
Boiler efficiency,% or COP	92	65	99	85	450
Fuel cost, rub/MJ	0.17	0.41	1.01	1.19	0,06
Fuel cost, rub/kW*h	0.61	1.48	3.65	4.29	0.22
Fuel cost, rub/Gcal	708	1722	4238	4989	253
Fuel cost per year, rub	24350	59257	145859	171721	8711
Service life of equipment, years	10	10	10	10	15
Approximate cost of equipment, rub	50000	70000	40000	100000	320000
Installation cost, rub	70000	30000	30000	30000	80000
The cost of connecting networks (technical conditions, equipment and installation), rub	120000	0	650	0	0
Initial investment, rub (approximately)	240000	100000	70650	130000	400000
Operating costs, rub/year	1000	1000	0	5000	0
Types of maintenance work	maintenance, camera cleaning	cleaning of the chamber, chimneys	Replacement of heating elements	chamber cleaning, injectors, filter replacement	No
Total expenses for the entire period of operation (including fuel costs), rub	493502	702572	1529236	1897201	530667
Total relative cost of 1 year of operation (fuel, depreciation, maintenance, etc.)	49350	70257	152924	189720	35378

Yes, the final line is really impressive, but is everything “smooth” here?

The first thing that will catch the eye of an attentive reader is that the electricity tariff for electric heating is taken as a general one, and for a heat pump, for some reason, a reduced night rate. Apparently, in order to make the final difference more visual.

Further. The cost of heat pump equipment is shown not quite correctly. If you take a closer look at the offers on the Internet, then the prices for installations with a capacity of about 7 ÷ 10 kW, which can be used for heating purposes, start from 300 - 350 thousand rubles (air heat pumps and low-power installations used only for hot water supply cost somewhat smaller).

It would seem that everything is correct, but "the devil is in the details" This is only the cost of the hardware unit itself, which, without peripheral devices, circuits, probes, etc. - useless. The price of only one collector (without pipes) will give at least 12 ÷ 15 thousand more, a borehole probe costs no less. And if we add the cost of pipes, fittings, shut-off and fitting elements, a sufficiently large amount of coolant, the total amount grows rapidly.

Pipes, collectors, valves are also quite a “weighty” item of general expenses.

But this is not all. It has already been mentioned that a heating system based on a heat pump, like probably no other, needs complex specialized calculations. When designing, a lot of factors are taken into account: the total area and volumes of the building itself, the degree of its insulation and the calculation of heat losses, the availability of a sufficient source of power supply, the presence of the necessary area of \u200b\u200bthe territory (nearby reservoir) for placing heat exchange horizontal circuits or drilling wells, the type and condition of soils , the location of aquifers and much more. Of course, both survey and design work will also require time and appropriate payment to specialists.

The installation of equipment “at random”, without proper design, is fraught with a sharp decrease in the efficiency of the system, and sometimes even local “environmental disasters” in the form of unacceptable hypothermia of the soil, wells or wells, reservoirs.

The next is the installation of equipment and the creation of heat exchange fields or wells. We have already mentioned the scale of earthworks, the depth of drilling. To fill the wells after the installation of the probes, a special concrete solution with a high degree of thermal conductivity is required. Plus to this - switching circuits, laying highways to the house, etc. - all this is another considerable "layer" of material costs. This also includes the purchase and installation of an accumulating tank with the necessary automatic control, alteration of the heating system for underfloor heating or the installation of special heat exchangers.

In a word, the costs are very impressive, and, probably, this is what keeps heating systems from heat pumps in the category of “exotics”, inaccessible to the vast majority of owners of private houses.

But what about their highest popularity and mass application in other countries? The fact is that government programs are working there to stimulate the population to use alternative sources of energy supply. Consumers who have expressed a desire to switch to these types of heating are eligible to receive government subsidies that largely cover the initial costs of designing and installing equipment. Yes, and the level of income of working citizens, to be honest, there a little higher than in our area.

For European cities and towns, this is a fairly familiar picture - a heat pump heat exchanger near the house

Summary - statements about the quick payback of such a project should be treated with a certain degree of caution. Before undertaking such a large-scale and responsible set of measures, one should carefully calculate and weigh all the "accounting" to the smallest detail, assess the degree of risk, one's financial capabilities, planned profitability, etc. Perhaps there are more rational, acceptable options - laying gas, installing modern ones, using new developments in the field of electric heating, etc.

What is written should not be taken as a “negative” about heat pumps. Of course, this is an extremely progressive direction, and it has great prospects. The point is only that in such matters one should not show rash voluntarism - decisions should be based on carefully thought-out and comprehensively carried out calculations.

Prices for the range of heat pumps

Heat pumps

Is it possible to assemble a heat pump with your own hands?

The general prospect of using "gratuitous" sources of thermal energy, combined with the continuing high price of equipment, willy-nilly lead many home craftsmen to create such heating installations on their own. Is it possible to manufacture a heat pump with your own strength?

Of course, it is quite possible to assemble such a heat engine using some ready-made units and the necessary materials. On the Internet, you can find both videos and articles with successful examples. True, it is unlikely that it will be possible to find exact drawings, everything is usually limited to recommendations on the possibility of manufacturing certain parts and assemblies. However, there is a rational “grain” in this: as already mentioned, a heat pump is such an individual system that requires calculations in relation to specific conditions that it will hardly be advisable to blindly copy other people's developments.

Nevertheless, those who nevertheless decide on independent production should heed some technological recommendations.

So, let's "bracket" the creation of external circuits - heating and primary heat exchange. The main task in this case is the manufacture of two heat exchangers, an evaporator and a condenser, connected by a copper tube circuit with a refrigerant circulating through it. This circuit, as can be seen from the circuit diagram, is connected to the compressor.

The compressor is easy to find - new or from equipment disassembled for spare parts

The compressor itself is not so difficult to get - it can be purchased new - in a specialized store. You can search in the household market - they often sell units from old refrigerators or air conditioners disassembled for parts. It is quite possible that the compressor will be found in their own stocks - many zealous owners do not throw away such things even when buying new household appliances.

Now - the question of heat exchangers. There are several different options here:

A. If it is possible to purchase finished plate heat exchangers , sealed in a sealed case, then a lot of problems will be solved immediately. Such devices have excellent heat transfer efficiency from one circuit to another - it is not without reason that they are used in heating systems when connecting autonomous intra-apartment wiring to the pipes of the central network.

Convenience is also in the fact that such heat exchangers are compact, have ready-made pipes, fittings or threaded connections for connection to both circuits.

Video: making a heat pump using ready-made heat exchangers

B. Heat pump version with heat exchangers made of copper tubes and closed tanks.

Both heat exchangers, in principle, are similar in design, but different containers can be used for them.

A cylindrical stainless steel tank with a capacity of about 100 liters is suitable for the condenser. It is necessary to place a copper coil in it, bringing its ends from above and below to the outside and hermetically sealing the passage points at the end of the assembly. The inlet must be located at the bottom, the outlet, respectively, at the top of the heat exchanger.

The coil itself is wound from a copper tube, which can be purchased at the store with a footage (wall thickness - at least 1 mm). As a template, you can take a large diameter pipe. The coils of the coil should be somewhat spaced apart, attaching, for example, to a perforated aluminum profile.

The heating water circuit can be connected by means of ordinary water pipes mounted (welded, soldered or screwed with a seal) at opposite ends of the heat exchange tank. The internal space of the heat exchanger is used for water circulation. The end result should be something like this:

For an evaporator, such difficulties are not needed - there are no high temperatures or excess pressure, so a voluminous plastic container will suffice. The coil winds in much the same way, its ends are brought out. Conventional plumbing connections are also sufficient to circulate water from the primary circuit.

The evaporator is also installed on brackets next to the condenser, and near them a platform is being prepared for mounting the compressor with its subsequent connection to the circuit.

Recommendations for piping the compressor, installing a throttle control valve, the diameter and length of the capillary tube, the need for a regeneration heat exchanger and etc.., will not be given - this should only be calculated and installed by a refrigeration specialist.

It should be remembered that it requires high skills in hermetic soldering of copper pipelines, the ability to properly pump refrigerant - freon, check and carry out a test run. In addition, this work is quite dangerous, requiring the observance of very specific precautionary rules.

IN. Heat pump with pipe heat exchangers

Another option for manufacturing heat exchangers. To do this, you will need metal-plastic and copper pipes.

Copper tubes are selected in two diameters - about 8 mm for the condenser, and about 5 ÷ 6 for the evaporator. Their length is respectively 12 and 10 meters.

Metal-plastic pipes are designed to circulate water through them from the primary heat exchange and heating circuits, and copper pipes of the heat pump's internal circuit will be located in their cavity. Accordingly, the diameter of the pipes can be taken 20 and 16 mm.

Metal-plastic pipes are stretched in length so that copper pipes can be inserted into them without much effort, which should protrude about 200 mm on each side.

A tee is put on and “packed” on each end of the pipe, so that the copper tube passes straight through it. The space between it and the body of the tee is securely sealed with a heat-resistant sealant. The remaining perpendicular outlet of the tee will serve to connect the heat exchanger to the water circuit.

Pipes are assembled in spirals. Be sure to immediately provide for their thermal insulation by wearing foam rubber insulating "shirts". The result is two finished heat exchangers.

You can place them one above the other in an improvised frame-type case. On the same frame, a platform for installing the compressor is also provided. And in order to reduce the transmission of vibration from it to the overall structure, the compressor can be mounted, for example, through automotive silent blocks.

To carry out the piping of the compressor and refueling the resulting circuit with freon, again, you will need to invite a refrigeration specialist.

You can install such a heat pump in its intended place and connect the tee fittings on the heat exchangers, each to its own circuit. It remains only to supply power and start the unit.

All considered home-made heat pumps are fully functional designs. However, one should not assume that it is so easy to completely solve the problem of cheap home heating. Here we are talking, rather, about the creation of existing models that require further refinement and modernization. Even experienced craftsmen who have already made more than one similar device are constantly looking for ways to improve, creating new “versions”.

Video: how the master improves his own heat pump

In addition, only the heat pump itself was considered, and for normal operation it requires control, monitoring, and adjustment equipment associated with the home heating system. Here you can no longer do without certain knowledge in the field of electrical engineering and electronics.

Again, we can return to the problems of calculations - will a home-made heat pump “pull” the heating system so as to become a real alternative to other heat sources? Often in these matters, home craftsmen have to "wander by touch." However, if the basic principle is mastered, and the first model is successfully earned, this is already a big victory. You can temporarily adapt your test sample to provide the house with hot water for domestic purposes, and start designing a more advanced unit yourself, taking into account the experience already gained and correcting the mistakes made.

Hot water supply - from the energy of the sun!

A very practical solution would be to use the energy of the sun's rays to provide domestic hot water. This source of alternative energy is much simpler and cheaper than a heat pump. How to do it - in a special publication of our portal.

A heat pump is a universal device that functionally combines the characteristics of an air conditioner, a water heater and a heating boiler. This device does not use conventional fuel, its operation requires renewable sources from the environment - the energy of 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, it is also environmentally friendly, since the heat source is not electricity or combustion products, but natural heat sources.

For a better understanding of how a heat pump works for heating a house, it is worth remembering the principle of operation of a refrigerator. Here the working substance evaporates, giving off cold. And in the pump, on the contrary, it condenses and produces heat.

How a heat pump works

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, ground, water, 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.

The principle of operation of a heat pump for heating a house

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

Advantages and disadvantages of heat pumps

The operation of heat pumps for home heating can be controlled by specially installed temperature controllers. The pump automatically turns on when the medium temperature drops below the set value and turns off if the temperature exceeds the 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. The main advantages of the device:

Reliability. The service life exceeds 15 years, all parts of the system have a high working resource, power surges do not harm the system.
Safety. No soot, no exhaust, no open flames, no gas leakage.
Comfort. The operation of the pump is silent, climate control and an automatic system, the operation of which depends on weather conditions, help to create coziness and comfort in the house.
Flexibility. The device has a modern stylish design, it can be combined with any home heating system.
Versatility. It is used in private, civil construction. Because it has a wide power range. Due to which 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 drawback - the high cost of equipment and its installation. To install the device, it is necessary to carry out earthworks 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 (they transfer heat through its source) and compression (the circulation of the working fluid occurs due to electricity). The most economical absorption devices, however, they are more expensive and have a complex design.

Classification of pumps by type of heat source:

Geothermal. They take heat from water or earth.
Air. They take heat from the air.
secondary heat. They take the so-called production heat - generated in production, during heating, and other industrial processes.

The heat carrier 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 soil, which it selects with vertical probes or a horizontal collector. Probes are placed at a depth of up to 70 meters, the probe is located at a small distance from the surface. This type of device is most efficient, since the heat source has a fairly high constant temperature throughout the year. Therefore, it is necessary to spend less energy on heat transportation.

Such equipment is expensive to install. The high cost of drilling wells. In addition, the area allotted for the collector should 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 pond is a source of a large amount 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 length of the pipe 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 groundwater. A pump is placed in the first well, supplying water to the heat exchanger. Chilled water enters the second well. This so-called open circuit of heat collection. Its main disadvantage is that the groundwater level is unstable and can change significantly.

Air is the most accessible source of heat

In the case of using air as a heat source, the heat exchanger is a radiator forcedly blown by a fan. If a heat pump works for heating a house using an air-to-water system, the user benefits from:

Possibility to heat the whole house. Water, acting as a heat carrier, is diluted through heating devices.
With minimal electricity consumption - the ability to provide residents with hot water. This is possible due to the presence of an additional heat-insulated heat exchanger with storage capacity.
Pumps of a similar type can be used to heat water in swimming pools.

If the pump operates on an air-to-air system, no heat carrier is used to heat the space. Heating is produced by the received thermal energy. An example of the implementation of such a scheme is a conventional air conditioner set to heating mode. Today, all devices that use air as a heat source are inverter-based. They convert alternating current to 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 use of devices everywhere. Now you know how a heat pump works for heating a house, and having calculated all the pros and cons, you can decide on its installation.

A heat pump is a good alternative to the traditional heating of a private house. The device, which has been used for 30 years in Western countries, is still a novelty in Russia. Two factors prevent its widespread use: high cost and lack of knowledge about heat pumps, their advantages and principles of operation. An indicator of the practicality of a geothermal heating system is its popularity in the West. Thus, about 95% of houses are heated with heat pumps in Sweden and Norway. We invite you to learn more about the device and the principles of operation of this thermal equipment, which, of course, is the future.

What is a heat pump?

A heat pump is a device that absorbs low-potential thermal energy from the environment (water, earth, air) and transfers it to heat supply systems with a higher temperature.

The nature around us is saturated with energy. Even frost has warmth. Energy cannot be extracted from the environment only at a temperature of -273 °C. Therefore, even in the most severe winter, a country house can be heated by energy obtained from nature.

Depending on the source of energy (water, earth, air), modification of heat pumps. However, the most practical and tried and tested is the ground source heat pump. It is ideal for Russian conditions.

Geothermal heating works in one of three directions:

The use of geothermal heating, like any heat supply system, will not only heat the house, but also provide hot water, heat a parking lot or a greenhouse, heat water in a swimming pool

Benefits of using a heat pump

How a heat pump works

The operation of a heat pump can be compared to that of a conventional refrigerator. Only instead of cold, the device produces heat. The substance that transmits energy is freon A gas or liquid with a low boiling point. When evaporating, it absorbs heat, and when condensing, it gives it away.

The heat pump is the main element of the system. Its dimensions do not exceed the dimensions of the average washing machine which makes it easier to install the device. The pump itself is included in two circuits: internal and external.

Inner contour consists of a house heating system (pipes and radiators). Outer loop located in water or underground. It includes a collector-heat exchanger and pipes connecting the collector to the pump.

Heat pumps are equipped with various additional devices. It can be:

communication device to control the system through a personal computer or mobile phone;
cooling block for local or central cooling system;
additional pump unit may be required for underfloor heating;
circulation pump necessary for the circulation of hot water;

The pumping process consists of several stages:

Anti-freeze mixture fed into the collector. Thermal energy is absorbed and transported to the pump.
In the evaporator, energy is transferred to freon, where it heats up up to 8 °C, boils and turns into steam.
As the pressure in the compressor increases, the temperature rises. It can reach 70°C.
The internal heating system receives thermal energy through capacitor. Freon instantly cools and turns into a liquid state, while giving off the remaining heat. Then it goes back to the collector. Thus the cycle ends.
Further work is repeated according to the same principle.

The heat pump operates most efficiently when there are underfloor heating in the house. Heat is distributed over the entire floor area evenly. There are no overheating zones. The heat carrier in the system rarely heats up more than 35 °C, and heating by floor heating is considered the most comfortable at 33 °C. This is 2 °C less than when heating with radiators. Hence arises saving up to 18% per year from the entire heating budget. In addition, it is believed that heating at floor level is the most comfortable for a person to live.

The heating system can be monovalent and bivalent. Monovalent systems have one heating source. It fully meets the year-round need for warmth. Bivalent, respectively, have two sources.

Heating the house in winter

In areas with more severe climatic conditions, it is important to use bivalent heating system. Due to the second heat source, the temperature range is extended. The operation of one heat pump is sufficient only up to a temperature level of -20 °C. With a larger decrease, an electric heater, fireplace, liquid fuel or gas boiler are connected. In this case, the power of the heat pump is limited from the maximum winter demand to 70 - 80%. The missing 20 - 30% gives an additional source of heat. This reduces the overall efficiency of the system. However, the decrease is insignificant.

With a complete transition to heating the building with a geothermal system (in the case when it is not planned to install an additional boiler or electrical appliance), the heat pump is used in conjunction with an indoor module containing a small built-in electric heater. It will support the instrument when the ambient temperature is below -20 °C.

When is the use of a heat pump justified?

The issue of heating a country house involves consideration of several options:

Gas. In the absence of a gas pipeline near the house, this becomes impossible. In some regions, gas can only be bought in bottles.
Coal or firewood. With them, heating turns into a laborious and inefficient process.
Oil boiler requires high fuel costs and special premises. Special storage is also necessary for the fuel itself, which is inconvenient in a small house.
Heating with electricity is very expensive.

In this case, help comes geothermal heating system. It is used even where gas is available. Installing a heat pump is more expensive than installing gas heating equipment. However, in the future, gas will have to be paid constantly, unlike energy taken from the environment.

The payback of a heat pump is difficult to express in an average numerical value. It all depends on its initial cost. The essence of the installation of such heating is reduced to perspective. Although the amount consumed electricity - 3-5 times less than other heating systems, it is still necessary to calculate in monetary terms all energy costs for the year and compare them with the cost of the system, its installation and operation.

It is possible to achieve the maximum efficiency of the use of a heat pump if two important conditions:

Heated building must be insulated, and the heat loss index should not exceed 100 W/m2. There is a direct relationship between how the house is insulated and how profitable the installation of a heat pump will be.
Connecting the heat pump to low temperature heating sources(convectors, warm floors), the temperature regime of which ranges between 30 - 40 °C.

So, the heat pump will be a good alternative to traditional heating methods. The device guarantees economy and complete safety. The owner, after installing a geothermal heating system, will not have to depend on various external factors, such as interruptions in gas supply or calling a service provider. Energy taken from the environment does not require payment and is not exhausted.