How to make a heat pump for heating a house with your own hands: operating principle and assembly diagrams

The first versions of heat pumps could only partially satisfy the needs for thermal energy.Modern varieties are more efficient and can be used for heating systems. This is why many homeowners try to install a heat pump with their own hands.

We will tell you how to choose the best option for a heat pump, taking into account the geodata of the area where it is planned to be installed. The article proposed for consideration describes in detail the principle of operation of “green energy” systems and lists the differences. With our advice, you will undoubtedly settle on an effective type.

For independent craftsmen, we present the technology for assembling a heat pump. The information presented for consideration is supplemented by visual diagrams, photo selections and a detailed video instruction in two parts.

What is a heat pump and how does it work?

The term heat pump refers to a set of specific equipment. The main function of this equipment is to collect thermal energy and transport it to the consumer. The source of such energy can be any body or environment with a temperature of +1º or more degrees.

There are more than enough sources of low-temperature heat in our environment. This is industrial waste from enterprises, thermal and nuclear power plants, sewage, etc. To operate heat pumps in home heating, three self-regenerating natural sources are needed - air, water, and earth.

Heat pumps draw energy from processes that regularly occur in the environment.The flow of processes never stops, because the sources are recognized as inexhaustible according to human criteria

The three listed potential energy suppliers are directly related to the energy of the sun, which, by heating, moves the air with the wind and transfers thermal energy to the earth. It is the choice of source that is the main criterion according to which heat pump systems are classified.

The operating principle of heat pumps is based on the ability of bodies or media to transfer thermal energy to another body or environment. Receivers and suppliers of energy in heat pump systems usually work in pairs.

The following types of heat pumps are distinguished:

• Air is water.
• Earth is water.
• Water is air.
• Water is water.
• Earth is air.
• Water - water
• Air is air.

In this case, the first word determines the type of medium from which the system takes low-temperature heat. The second indicates the type of carrier to which this thermal energy is transferred. So, in heat pumps, water is water, heat is taken from the aquatic environment and liquid is used as a coolant.

By design, heat pumps are vapor compression units. They extract heat from natural sources, process and transport it to consumers (+)

Modern heat pumps use three main thermal energy source. These are soil, water and air. The simplest of these options is air source heat pump. The popularity of such systems is due to their fairly simple design and ease of installation.

However, despite such popularity, these varieties have rather low productivity. In addition, the efficiency is unstable and dependent on seasonal temperature fluctuations.

As the temperature drops, their performance drops significantly. Such heat pump options can be considered as an addition to the existing main source of thermal energy.

Equipment options using ground heat, are considered more effective. The soil receives and accumulates thermal energy not only from the Sun, it is constantly heated by the energy of the earth's core.

That is, the soil is a kind of heat accumulator, the power of which is practically unlimited. Moreover, the soil temperature, especially at some depth, is constant and fluctuates within insignificant limits.

Scope of application of energy generated by heat pumps:

The constancy of the source temperature is an important factor in the stable and efficient operation of this type of power equipment. Systems in which the aquatic environment is the main source of thermal energy have similar characteristics. The collector of such pumps is located either in a well, where it ends up in an aquifer, or in a reservoir.

The average annual temperature of sources such as soil and water varies from +7º to + 12º C. This temperature is quite enough to ensure efficient operation of the system.

The most effective are heat pumps that extract thermal energy from sources with stable temperature indicators, i.e. from water and soil

Basic design elements of heat pumps

In order for the energy production installation to operate according to the operating principles of a heat pump, its design must contain 4 main units, these are:

• Compressor.
• Evaporator.
• Capacitor.
• Throttle valve.

An important element of the heat pump design is the compressor. Its main function is to increase the pressure and temperature of the vapors formed as a result of the boiling of the refrigerant. Modern scroll compressors are used in particular for climate control equipment and heat pumps.

Liquids with a low boiling point are used as a working fluid that directly transfers thermal energy. As a rule, ammonia and freons are used (+)

Such compressors are designed for operation at sub-zero temperatures. Unlike other types, scroll compressors produce little noise and operate at both low gas boiling temperatures and high condensation temperatures. An undoubted advantage is their compact size and low specific weight.

Almost all the energy of a heat pump is spent on transporting thermal energy from outside to inside the room. So it takes about 1 energy unit to operate the systems when producing 4 - 6 units (+)

The evaporator as a structural element is a container in which liquid refrigerant is converted into vapor. The refrigerant, circulating in a closed circuit, passes through the evaporator. In it, the refrigerant heats up and turns into steam.The resulting steam is directed towards the compressor under low pressure.

In the compressor, the refrigerant vapors are pressurized and their temperature increases. The compressor pumps heated steam under high pressure towards the condenser.

The compressor compresses the medium circulating along the circuit, resulting in an increase in its temperature and pressure. Then the compressed medium enters the heat exchanger (condenser), where it is cooled, transferring heat to water or air

The next structural element of the system is the capacitor. Its function is reduced to the release of thermal energy to the internal circuit of the heating system.

Serial samples manufactured by industrial enterprises are equipped with plate heat exchangers. The main material for such capacitors is alloy steel or copper.

To make your own heat exchanger, a copper tube with a diameter of half an inch is suitable. The wall thickness of the pipes used to manufacture the heat exchanger must be at least 1 mm

The thermostatic, or otherwise throttle, valve is installed at the beginning of that part of the hydraulic circuit where the high-pressure circulating medium is converted into a low-pressure medium. More precisely, a throttle paired with a compressor divides the heat pump circuit into two parts: one with high pressure parameters, the other with low pressure parameters.

When passing through the expansion throttle valve, the liquid circulating in a closed circuit partially evaporates, as a result of which the pressure and temperature drop. Then it enters a heat exchanger that communicates with the environment. There it captures the energy of the environment and transfers it back into the system.

The throttle valve regulates the flow of refrigerant towards the evaporator. When choosing a valve, you need to take into account the system parameters. The valve must meet these parameters.

When passing through the heat control valve, the coolant liquid partially evaporates and the flow temperature decreases (+)

Selecting a heat pump type

The main indicator of this heating system is power. The financial costs of purchasing equipment and choosing one or another source of low-temperature heat will primarily depend on the power. The higher the power of the heat pump system, the higher the cost of the components.

First of all, we mean the power of the compressor, the depth of the wells for geothermal probes, or the area for placing a horizontal collector. Correct thermodynamic calculations are a kind of guarantee that the system will operate efficiently.

If there is a pond near your personal property, the most cost-effective and productive choice would be a water-to-water heat pump

First, you should study the area that is planned for installing the pump. The ideal condition would be the presence of a reservoir in this area. Usage water-water type option will significantly reduce the volume of excavation work.

Using the heat of the earth, on the contrary, involves a large number of works related to excavation. Systems that use aqueous media as low-grade heat are considered the most efficient.

The design of a heat pump that extracts thermal energy from the ground requires an impressive amount of excavation work. The collector is laid below the seasonal freezing level

The thermal energy of the soil can be used in two ways. The first involves drilling wells with a diameter of 100-168 mm. The depth of such wells, depending on the system parameters, can reach 100 m or more.

Special probes are placed in these wells. The second method uses a pipe collector. Such a collector is located underground in a horizontal plane. This option requires a fairly large area.

Areas with moist soil are considered ideal for laying the collector. Naturally, drilling wells will cost more than horizontally positioning the reservoir. However, not every site has free space. For one kW of heat pump power you need from 30 to 50 m² of area.

A structure for collecting thermal energy with one deep well may turn out to be slightly cheaper than digging a pit. But a significant plus is the significant space saving, which is important for owners of small plots

If there is a high-lying groundwater horizon on the site, heat exchangers can be installed in two wells located at a distance of about 15 m from each other.

Thermal energy is collected in such systems by pumping groundwater through a closed circuit, parts of which are located in wells. Such a system requires installing a filter and periodically cleaning the heat exchanger.

The simplest and cheapest heat pump scheme is based on extracting thermal energy from the air. It once became the basis for refrigerators; later, air conditioners were developed according to its principles.

The simplest heat pump system receives energy from the air mass. In summer it is involved in heating, in winter in air conditioning.The disadvantage of the system is that the stand-alone unit has insufficient power

The effectiveness of different types of this equipment is not the same. Pumps using air have the lowest performance. In addition, these indicators directly depend on weather conditions.

Ground-based types of heat pumps have stable performance. The efficiency coefficient of these systems varies between 2.8 -3.3. Water-to-water systems are most effective. This is due, first of all, to the stability of the source temperature.

It should be noted that the deeper the pump manifold is located in the reservoir, the more stable the temperature will be. To obtain a system power of 10 kW, about 300 meters of pipeline are required.

The main parameter characterizing the efficiency of a heat pump is its conversion coefficient. The higher the conversion factor, the more efficient the heat pump is considered.

The conversion coefficient of a heat pump is expressed through the ratio of heat flow and electrical power expended to operate the compressor

Assembling a heat pump yourself

Knowing the operating diagram and structure of the heat pump, assemble and install it yourself alternative heating system quite possible. Before starting work, it is necessary to calculate all the main parameters of the future system. To calculate the parameters of the future pump, you can use software designed to optimize cooling systems.

The easiest option to construct is air-water system. It does not require complex work on the construction of an external circuit, which is inherent in water and ground-based types of heat pumps. For installation, you will only need two channels, one of which will supply air, and the second will discharge the waste mass.

The easiest way is to build a heat pump with your own hands that extracts heat from the air mass. An outdoor fan blows air to the evaporator

In addition to the fan, you need to get a compressor of the required power. For such a unit, the compressor that is equipped with conventional split systems. It is not necessary to buy a new unit.

You can remove it from old equipment or use it old refrigerator components. It is advisable to use the spiral variety. These compressor options, in addition to being quite efficient, create high pressures that produce higher temperatures.

To install a capacitor you will need a container and a copper pipe. A coil is made from a pipe. For its manufacture, any cylindrical body of the required diameter is used. By winding a copper pipe around it, you can easily and quickly produce this structural element.

The finished coil is mounted in a container previously cut in half. For the manufacture of containers, it is better to use materials that are resistant to corrosion processes. After placing the coil in it, the tank halves are welded.

The coil area is calculated using the following formula:

MT/0.8 RT,

Where:

• MT - the power of thermal energy that the system produces.
• 0,8 — thermal conductivity coefficient when water interacts with the coil material.
• RT — difference in water temperatures at the inlet and outlet.

When choosing a copper pipe for making a coil yourself, you need to pay attention to the wall thickness. It must be at least 1 mm. Otherwise, the pipe will be deformed during winding. The pipe through which the refrigerant enters is located in the upper part of the container.

A copper tube heat exchanger is made by winding a copper tube onto a cylindrical shaped object. The larger the surface area of ​​the coil, the higher the pump performance

The heat pump evaporator can be made in two versions - in the form of a container with a coil located in it and in the form of a pipe in a pipe. Since the temperature of the liquid in the evaporator is low, the container can be made from a plastic barrel. A circuit made of copper pipe is placed in this container.

Unlike a condenser, the coil of the evaporator coil must match the diameter and height of the selected container. The second evaporator option: pipe in pipe. In this embodiment, the refrigerant tube is placed in a larger diameter plastic pipe through which water circulates.

The length of such a pipe depends on the planned pump power. It can be from 25 to 40 meters. Such a pipe is rolled into a spiral.

The thermostatic valve refers to shut-off and control pipeline fittings. A needle is used as a closing element in the expansion valve. The position of the valve shut-off element is determined by the temperature in the evaporator.

This important element of the system has a rather complex design. It includes:

• Thermocouple.
• Diaphragm.
• Capillary tube.
• Thermal balloon.

These elements may become unusable at high temperatures.Therefore, during soldering work on the system, the valve should be insulated with asbestos fabric. The control valve must match the evaporator capacity.

After carrying out the work on the manufacture of the main structural parts, the crucial moment comes when assembling the entire structure into a single block. The most critical stage is refrigerant injection process or coolant into the system.

An ordinary person is unlikely to be able to carry out such an operation independently. Here you will have to turn to professionals who repair and maintain climate control equipment.

Workers in this field usually have the necessary equipment. In addition to charging refrigerant, they can test the operation of the system. Injecting refrigerant yourself can lead not only to structural failure, but also to serious injury. In addition, special equipment is also required to run the system.

When the system starts, a peak starting load occurs, usually around 40 A. Therefore, starting the system without a starting relay is impossible. After the first start-up, adjustment of the valve and refrigerant pressure is necessary.

The choice of refrigerant should be taken very seriously. After all, it is this substance that is essentially considered the main “carrier” of useful thermal energy. Of the existing modern refrigerants, freons are the most popular. These are derivatives of hydrocarbon compounds in which some of the carbon atoms are replaced by other elements.

As a result of assembling the individual elements of the heat pump, a closed loop should be obtained through which the working medium circulates

As a result of this work, a closed-loop system was obtained. The refrigerant will circulate in it, ensuring the selection and transfer of thermal energy from the evaporator to the condenser. When connecting heat pumps to the home heating system, it should be taken into account that the temperature of the water leaving the condenser does not exceed 50 - 60 degrees.

Due to the low temperature of the thermal energy generated by the heat pump, specialized heating devices must be selected as a heat consumer. This can be a warm floor or volumetric low-inertia radiators made of aluminum or steel with a large radiation area.

Homemade heat pump options are most appropriately considered as auxiliary equipment that supports and complements the operation of the main source.

Every year, heat pump designs are improved. Industrial designs intended for domestic use use more efficient heat transfer surfaces. As a result, system performance is constantly increasing.

An important factor that stimulates the development of such technology for the production of thermal energy is the environmental component. Such systems, in addition to being quite effective, do not pollute the environment. The absence of open flame makes its operation absolutely safe.

Conclusions and useful video on the topic

Video #1. How to make a simple homemade heat pump with a heat exchanger from PEX pipes:

Video #2. Continuation of the instruction:

Heat pumps have been used as alternative heating systems for quite some time.These systems are reliable, have a long service life and, importantly, are environmentally friendly. They are beginning to be seriously considered as the next step towards the development of efficient and safe heating systems.

Do you want to ask a question or tell us about an interesting way to build a heat pump that is not mentioned in the article? Please write comments in the block below.