Heat pump- a mechanical device that allows for heat transfer from a resource with low potential thermal energy (low temperature) to a heating system (coolant) with an elevated temperature. Let's try to explain this in more understandable language.
Gone are the days when people heated their homes by burning wood in fireplaces or stoves. They are being replaced by multifunctional long-burning boilers. In regions where main gas is available, efficient gas equipment is used for heating. In places inaccessible to gas mains, it is increasingly used.
Humanity understands that burning non-renewable energy sources is not a promising business; resources are gradually depleted. Scientists don't stop searching new ways of producing thermal energyand develop modern mechanisms to implement the assigned tasks.
In one such project, a heat pump was designed. Indeed, just like to the majority heat-generating units, the operation of a heat pump is not possible without electrical energy. A serious difference is that electricity is not involved in heating, for example, a heating element, as in an oil radiator, and does not close the spiral in a heat gun. A heat pump does not have heating elements, it does not create thermal energy, the heat pump only serves as a carrier of it from the environment to the consumer (coolant).
The electricity consumed by the heat pump is spent only on compressing the refrigerant and pumping it around to circulate it. The refrigerant acts as a necessary working environment, it is he who moves heat from the environment to the heating system and hot water supply system. This review will help us how to choose a heat pump, the principle of its operation, and also learn about the pros and cons of such equipment.
Heat pump for heating
Traditional heating of a private home is still preferable if inexpensive resources are abundant. The question is, what to do when the availability of cheap sources is limited? An alternative solution is a heat pump - more than 40 years of operating experience in the European Union tells us that this can be very effective.
In the Russian Federation, the heat pump has not received proper distribution. The reason for this is two factors. Firstly, there is an abundance of oil, gas, and wood. Secondly, it is stopped by the high price and lack of popularization. Information about heat pumps is very scarce, the principle of their operation is not clear, and there is not enough information about the benefits.
In the European Union, fuel prices are so high that geothermal heating systems show benefits in operation. For example, up to 95% of households in Sweden and Norway they useheat pumps as the main source of heating. The International Energy Agency predicts that heat pumps will begin to provide 10% of energy demand for heating in Organization for Economic Cooperation and Development countries by 2020, and by 2050 this figure will reach 30%.
Heat pump for heating - operating principle
From a school physics course, recalling the second law of thermodynamics, it is known for certain that heat from a hot body is transferred to a cold one without any mechanisms. The trick is how to transfer heat in the opposite direction? To do this, we will need a series of actions that ensure results.
These are the actions that a heat pump will help us perform. The energy costs for operating a heat pump depend proportionally on the temperature difference between the media involved in this process.
Have you ever touched the black grille of a refrigerator at the back? Anyone can verify that the back wall is very hot. Pointing a laser pyrometer at the black grating, you can see that its surface temperature is about 40°C. In this way, refrigeration equipment engineers recover unnecessary heat from inside the freezer.
It is known that in the late forties of the last century, inventor Robert Weber drew attention to the useless heating of air with a refrigerator radiator. The inventor thought about it and connected an indirect heating boiler to it. As a result, Robert supplied the household with hot water in the required volume. It was then that the enthusiast began to think about how to “turn” the refrigerator inside out and transform the cooling device into a heating device. I must admit, he succeeded.
How does a heat pump work?
The principle of operation of a heat pump is based on the fact that underground at any time of the year, falling below the freezing level, we will encounter temperatures above zero. It turns out that the frost-free soil layer is right under our feet. What if you use it as the back wall of the freezer?
Applying the operating principle of refrigeration equipment, To transfer heat from the underground to the home space, a system of pipes is used through which refrigerant circulates. Freon refrigerants are heated by underground heat and begin to evaporate. Cold air from outside cools it, causing the freon to condense.
By heating the heat by alternating cycles of evaporation and heating, the heat pump forces the refrigerant to circulate. The compressor creates pressure, forcing freon to move through the tubes of two heat exchangers.
In the first heat exchanger, freon evaporates at low pressure, during which heat is absorbed from the immediate surrounding atmosphere. The same refrigerant is then compressed by a high-pressure compressor and moved to a second coil where it is condensed. It then releases the heat it absorbed earlier in the cycle.
The booster compressor plays the main role in the process. By increasing the pressure, the freon condenses and produces more heat than it received from the warm earth. Thus, ground positive values of + 7 ° C andtransforms into comfortable home conditions + 24°C.
By using a heat pump for heating, we achieve high efficiency.
I would like to note that the entire structure does not require a specially dedicated electrical wiring line. Power consumption is comparable to the energy consumption of a household electric kettle. The trick is that the heat pump “produces” thermal energy four times more than it consumes electricity. To heat a cottage of 300 m2, in severe frosts of 30°C, no more than 3 kW will be spent.
However, the owner of a geothermal pump will have to fork out a lot at the beginning. The cost of equipment and materials for connection is at least $4,500. Let's add installation work and drilling, and the same amount, it turns out that the simplest system will cost 10 thousand dollars.
It is clear that it will cost an order of magnitude cheaper. But pay monthly based on 1 kW per 10 m2will have to anyway. So it turns out that for 300 sq. meters at home it will take 30 kW - 10 times more than will be spent on a heat pump.
Calculations for heating with gas using a gas boiler give approximately the same figures - 2000 rubles per month, which is comparable to the operation of a heat pump. Unfortunately, not everyone lives in a gasified area.
The heat pump has an undeniable advantage. In the summer, such a “reverse freezer” can be “turned inside out” and with a slight movement of the hand, the heat pump turns into an air conditioner. On hot days it’s +30°C outside, but in the dungeon it’s cool. Using tubes filled with coolant, the pump will transfer the cold of the underground into the home. Next, the fan is turned on, so we get an economical cooling system.
Operating practice indicates payback periods from 3 to 7 years. The Scandinavian countries have long calculated their profits and heat themselves using this method. A striking example is the giant heat pump in Stockholm, geothermal equipment. The source of thermal energy in winter and coolness in summer is the waters of the Baltic Sea. The slogan fully applies to the heat pump: pay now - save later! Savings are becoming greater due to the fact that energy resources are becoming more expensive.
Heat pump. The truth about its effectiveness.
Unfortunately, not everything is so rosy with efficiency today. One of the main questions tormenting the consumer remains: to buy or not to buy a heat pump. Our advice is to carefully weigh the pros and cons; most likely, the option of buying a conventional one will cost less after use, and installation will be easier.
If we consider a heat pump as a concept of the future, as a new idea for generating heat, the engineering idea definitely deserves respect. Geothermal equipment works, you can touch it with your hands, and every year it becomes more and more efficient. However, if we calculate how much money we will spend on its operation, add the initial costs of purchase and installation, we will most likely get an amount showing that we will spend much more money on it than on any other type of heat generating device.
Considering a heat pump as an economic system, when you spend 100 rubles on its operation and receive 300 rubles worth of thermal energy, do not forget that you paid a lot of money for the right to receive an excess profit of 200 rubles. By the way, in the European Union, sales of heat pumps are supported by government programs.
So in Finland, more than 60 thousand heat pumps are sold annually and the number of sales is growing at a 5% rate. But firstly, the economic effect of using such equipment there is higher due to expensive electricity. The cost of electricity in Finland is 35 euro cents, compared to Russia - 7 euro cents. Secondly, the subsidy program provides reimbursement for the purchase of a heat pump in the amount of 3,000 EURO.
As long as gas and electricity prices remain low, introducing a heat pump as a major competitor remains challenging. Mass consumption will become possible only in the event of a crisis with hydrocarbon production or a crisis with electricity generation.
How to choose the right heat pump
First stage.
Calculation of the required heat for heating a house. To select a heat pump (HP) that is included in the heating system of a house, it is important to calculate the heat demand. An accurate calculation will help you avoid unnecessary cost overruns, as this leads to unnecessary expenses.
Second phase.
Which heat source to choose for your heat pump. This decision depends on many components, the main ones:
- Financial component. This includes the direct cost of the equipment itself, as well as the work of installing a geothermal probe or laying an underground thermal circuit. This depends on the location of the site itself, as well as on the immediate surroundings (reservoirs, buildings, communications) and geology.
- Operational component. The main cost is the operation of the heat pump. This figure depends on the heating mode of your building and the selected heat source.
Third stage.
Analysis of initial data for selecting a heat pump:
- Budget for the proposed system.
- Heating system: radiators, air heating, heated floor.
- The area of the site that can be allocated for laying a thermal collector.
- Is it possible to drill on the site?
- Geology of the site to determine the depth of the geothermal probe if such a decision is made.
- Is air conditioning required in summer?
- Is air heating available or planned in the future?
- Capital cost of purchase and installation of the HP with all work (approximate initial estimate).
Let's sort it all out in order
Budget for the proposed system
When creating a heating system using a heat pump, it is possible to install an air-water circuit. Capital investments will be minimal, since no expensive excavation work is required. But there will be high costs during the operation phase of this heating system due to low operating efficiency.
If you want to significantly reduce operating costs, then installing a geothermal pump is suitable for you. True, it will be necessary to carry out excavation work to lay the thermal circuit. This system will also provide “passive” cold.
Heating system: radiators, air heating, heated floors
To increase the efficiency of the HP system, it is desirable to reduce the difference between the temperature of the heated medium and the temperature of the heat source.
If you have not yet chosen a heating system, it is recommended to choose heated floors, which allow you to use the heating system more efficiently.
Area of land that can be allocated for laying a thermal collector
The area of the site for installing the collector is critical if it is impossible to drill and install a geothermal probe. Then you will have to lay the collector horizontally, and this will require a space approximately 2 times larger than the area of the heated house. It should be taken into account that this area cannot be used for development, but only in the form of a lawn or lawn, so as not to block the flow of sunlight.
Is it possible to drill on the site?
If it is possible to drill on the site (good geology, access, lack of underground communications), the best solution would be to install a geothermal probe. It provides a stable and long-term heat source.
Geology of the site to determine the depth of the geothermal probe, if such a decision is made
After calculating the total drilling depth, it is necessary to study the site plan and determine how to ensure the drilling depth. In practice, the depth of one well usually does not exceed 150 m.
Therefore, if, for example, the estimated drilling depth is 360 m, then, based on the characteristics of the site, it can be divided into 4 wells of 90 m each, or 3 of 120 m each, or 6 of 60 m each. But we must take into account that the distance between the nearest wells should not be less than 6 m.
The cost of drilling operations is directly proportional to the drilling depth.
Is air conditioning required in summer?
If air conditioning is required in the summer, then the obvious choice is a heat pump of the “water-to-water” or “ground-to-water” type; other heat pumps are not ready to effectively and economically perform air conditioning functions.
Is air heating available or planned in the future?
It is possible to integrate the heat pump into a single air heating system. This solution will allow to unify engineering networks.
Capital cost of purchasing and installing a heat pump with all work
The initial estimated capital costs* for purchase and installation depend on the type of heat pump:
HP with underground collector:
Works - $2500
Operating costs - $350/year
VT with probe:
Equipment and materials - $4500
Works - $4500
Operating costs - $320/year
Air VT:
Equipment and materials - $6500
Work - $400
Operating costs - $480/year
TN “water-water”:
Equipment and materials - $4500
Works - $3500
Operating costs - $280/year
* – approximate, average market prices. The final cost depends on the selected equipment manufacturer, the region of work performed, the cost of drilling operations and site conditions, and so on. Estimating department note
Fourth stage. Types of work
Single. The heat pump is the only heat source, providing 100% of the heat demand. Works for operating temperatures not higher than 55 °C.
Paired. The HP and the boiler work together, which allows the boiler to achieve higher operating temperatures.
Monoenergetic. The HP and the electric boiler form a power system with only one external energy source. This allows you to smoothly regulate power consumption, but increases the load on the input machine.
Selecting a heat pump
After collecting all the initial data and working out the main technical solutions, it is possible to select the appropriate type of HP. The configuration and choice of equipment supplier will depend on your financial capabilities. The main thing is to approach the choice of system with a full understanding of what you want. We will help you choose and implement a comfortable heating system. It can take into account all the nuances: from the climate control function to the distribution of heat across zones of the house.
Conclusion
By choosing an ecological heating system with a heat pump, you can be confident in the future. You get complete independence from heat supply organizations, world oil prices and the political situation in the country. The only thing you need is electricity. But over time, the generation of electricity can be transferred to absolute autonomy with the help of a windmill.
Article outline
A heat pump is a device that heats water from heating and hot water supply systems by compressing freon, initially heated from a low-grade heat source, by a compressor to 28 bar. Under high pressure, a gaseous coolant with an initial temperature of 5-10 ° C; releases a large amount of heat. This allows you to warm up the coolant of the consumption system to 50-60 °C, without the use of traditional types of fuel. Therefore, it is believed that a heat pump provides the user with the cheapest heat.
For more information about the advantages and disadvantages, watch the video:
Such equipment has been in operation for more than 40 years in Sweden, Denmark, Finland and other countries that support the development of alternative energy at the state level. Not so actively, but more confidently every year, heat pumps are entering the Russian market.
Purpose of the article: review popular heat pump models. The information will be useful to those who seek to save as much as possible on heating and hot water supply of their own home.
The heat pump heats the house with free energy from nature
In theory, heat can be extracted from the air, soil, groundwater, wastewater (including from a septic tank and water pumping station), and open reservoirs. In practice, for most cases, the feasibility of using equipment that takes thermal energy from the air and soil has been proven.
Options with heat extraction from a septic tank or sewage pumping station (SPS) are the most tempting. By passing the coolant through the HP at 15-20 °C, the output temperature can be at least 70 °C. But this option is acceptable only for a hot water supply system. The heating circuit reduces the temperature in the "tempting" source. Which leads to a number of unpleasant consequences. For example, freezing of drains; and if the heat exchange circuit of the heat pump is located on the walls of the sump, then the septic tank itself.
The most popular HPs for the needs of CO and DHW are geothermal (using the heat of the earth) devices. They are distinguished by their best performance in warm and cold climates, in sandy and clayey soils with different groundwater levels. Because the soil temperature below the freezing depth remains almost unchanged throughout the year.
Operating principle of a heat pump
The coolant is heated from a source of low-potential (5...10 °C) heat. The pump compresses the refrigerant, the temperature of which rises (50...60 °C) and heats the coolant of the heating system or hot water supply.
During the operation of the HP, three thermal circuits are involved:
- external (system with coolant and circulation pump);
- intermediate (heat exchanger, compressor, condenser, evaporator, throttle valve);
- consumer circuit (circulation pump, heated floor, radiators; for hot water supply - tank, water points).
The process itself looks like this:
Thermal energy removal circuit
- The soil heats the saline solution.
- The circulation pump lifts the brine into the heat exchanger.
- The solution is cooled by a refrigerant (freon) and returned to the ground.
Heat exchanger
- Liquid freon, evaporating, takes away thermal energy from the brine.
- The compressor compresses the refrigerant, causing its temperature to rise sharply.
- In the condenser, freon transfers energy through the evaporator to the coolant of the heating circuit and becomes liquid again.
- The cooled refrigerant goes through the throttle valve to the first heat exchanger.
Heating circuit
- The heated coolant of the heating system is drawn by the circulation pump to the dissipating elements.
- Transfers thermal energy to the air mass of the room.
- The cooled coolant returns through the return pipe to the intermediate heat exchanger.
Video with a detailed description of the process:
What is cheaper for heating: electricity, gas or heat pump?
We present the costs of connecting each type of heating. To present the general picture, let’s take the Moscow region. Prices may differ in regions, but the price ratio will remain the same. In the calculations we assume that the site is “bare” - without gas or electricity.
Connection costs
Heat pump. Laying a horizontal contour at MO prices - 10,000 rubles per shift of an excavator with a bucket bucket (removes up to 1,000 m³ of soil in 8 hours). A system for a house of 100 m² will be buried in 2 days (true for loam, on which you can remove up to 30 W of thermal energy from 1 square meter of circuit). About 5,000 rubles will be required to prepare the circuit for operation. As a result, the horizontal option for placing the primary circuit will cost 25,000.
The well will be more expensive (1,000 rubles per linear meter, taking into account the installation of probes, piping them into one line, filling with coolant and pressure testing), but it will be much more profitable for future operation. With a smaller occupied area of the site, the output increases (for a 50 m well - at least 50 W per meter). The pump's needs are covered and additional potential appears. Therefore, the entire system will not work for wear, but with some reserve power. Place 350 meters of contour in vertical wells – 350,000 rubles.
A gas boiler. In the Moscow region, for connection to the gas network, work on the site and installation of the boiler, Mosoblgaz requests from 260,000 rubles.
Electric boiler. Connecting a three-phase network will cost 10,000 rubles: 550 for local electrical networks, the rest for the distribution board, meter and other contents.
Consumption
To operate a HP with a thermal power of 9 kW, 2.7 kW/h of electricity is required - 9 rubles. 53 kopecks at one o'clock,
The specific heat during combustion of 1 m³ of gas is the same 9 kW. Household gas for Moscow region is priced at 5 rubles. 14 kopecks per cubic meter
An electric boiler consumes 9 kW/h = 31 rubles. 77 kop. at one o'clock. The difference with TN is almost 3.5 times.
Exploitation
- If gas is supplied, then the most cost-effective option for heating is a gas boiler. The equipment (9 kW) costs at least 26,000 rubles, the monthly payment for gas (12 hours per day) will be 1,850 rubles.
- Powerful electrical equipment is more profitable from the point of view of organizing a three-phase network and purchasing the equipment itself (boilers - from 10,000 rubles). A warm house will cost 11,437 rubles per month.
- Taking into account the initial investment in alternative heating (equipment 275,000 and installation of a horizontal circuit 25,000), a heat pump that consumes electricity at 3,430 rubles/month will pay for itself no earlier than in 3 years.
Comparing all heating options, provided that the system is created from scratch, it becomes obvious: gas will not be much more profitable than a geothermal heat pump, and heating with electricity in the next 3 years is hopelessly inferior to both of these options.
Detailed calculations in favor of operating a heat pump can be found by watching a video from the manufacturer:
Some additions and experience of effective operation are highlighted in this video:
Main characteristics
When choosing equipment from a wide variety of specifications, pay attention to the following characteristics.
| Characteristics | Range of values | Peculiarities |
|---|---|---|
| Thermal power, kW | Up to 8 | Premises with an area of no more than 80 - 100 m², with a ceiling height of no more than 3 m. |
| 8-25 | For one-level country houses with a ceiling of 2.5 m, an area of 50 m²; cottages for permanent residence, up to 260 m². | |
| Over 25 | It is advisable to consider for 2-3 level residential buildings with ceilings of 2.7 m; industrial facilities - no more than 150 m², with a ceiling height of 3 or more. | |
| Power consumption of main equipment (maximum consumption of auxiliary elements) kW/h | From 2 (from 6) | Characterizes the energy consumption of the compressor and circulation pumps (heating elements). |
| Scheme of work | Air-to-air | The transformed thermal energy of the air is transferred into the room by a flow of heated air through a split system. |
| Air - water | The energy removed from the air passed through the device is transferred to the coolant of the liquid heating system. | |
| Brine-water | The transfer of thermal energy from a renewable source is carried out by a sodium or calcium solution. | |
| Water-water | Through the open primary circuit, groundwater carries thermal energy directly to the heat exchanger. | |
| Outlet coolant temperature, °C | 55-70 | The indicator is important for calculating losses on a long heating circuit and when organizing an additional hot heat supply system. |
| Mains voltage, V | 220, 380 | Single-phase - power consumption no more than 5.5 kW, only for a stable (lightly loaded) household network; the cheapest - only through a stabilizer. If there is a 380 V network, then three-phase devices are preferable - a larger power range, less likely to “sag” the network. |
Model summary table
In the article, we examined the most popular models and identified their strengths and weaknesses. The list of models can be found in the following table:
| Model (country of origin) | Peculiarities | price, rub. |
|---|---|---|
|
Heat pumps for heating small spaces or domestic hot water |
||
| 1. | Air-water system; works from a single-phase network; the protruding condensation line is inserted into the water tank. | 184 493 |
| 2. | "Brine-water"; power supply from a three-phase network; variable power control; possibility of connecting additional equipment - recuperator, multi-temperature equipment. | 355 161 |
| 3. | Air-water heat pump powered by 220V mains and with frost protection function. | 524 640 |
| Equipment for heating systems of cottages for permanent residence | ||
| 4. | “Water - water” scheme. In order for the HP to produce a stable 62 °C coolant in the heating system, the capabilities of the set of compressor and pumps (1.5 kW) are complemented by an electric heater with a power of 6 kW. | 408 219 |
| 5. | Based on the air-water circuit, the potentials of cooling and heating devices are realized in one device, consisting of two blocks. | 275 000 |
| 6. | “brine-water”, the device heats the coolant for radiators up to 60 °C, can be used when organizing cascade heating systems. | 323 300 |
| 7. | In the same housing with the geothermal pump there is a storage tank for the hot water supply system, for 180 liters of coolant | 1 607 830 |
| Powerful heat pumps for heating and hot water supply needs | ||
| 8. | It is possible to extract heat from soil and groundwater; operation as part of cascade systems and remote control are possible; works from a three-phase network. | 708 521 |
| 9. | "brine-water"; control of the compressor power and the rotation speed of the circulation pumps is carried out through frequency adjustment; additional heat exchanger; network – 380 V. | 1 180 453 |
| 10. | “water-to-water” operating diagram; built-in primary and secondary circuit pumps; The possibility of connecting solar systems is provided. | 630 125 |
Heat pumps for heating small spaces or domestic hot water
Purpose – economical heating of residential and auxiliary premises, maintenance of the hot water supply system. Single-phase models have the lowest consumption (up to 2 kW). To protect against power surges in the network, they need a stabilizer. The reliability of three-phase is explained by the characteristics of the network (the load is distributed evenly) and the presence of its own protective circuits that prevent damage to the device due to voltage surges. Equipment in this category does not always cope with simultaneous maintenance of the heating system and hot water supply circuit.
1. Huch EnTEC VARIO China S2-E (Germany) – from RUB 184,493.
The Huch EnTEC VARIO cannot be operated independently. Only in conjunction with the storage tank of the hot water supply system. The HP heats water for sanitary needs, cooling the air in the room.
Among the advantages are the low energy consumption of the device, an acceptable water temperature in the DHW circuit and the function of cleaning the system (by periodic short-term heating to 60 ° C) from pathogenic bacteria that develop in a humid environment.
The disadvantages are that gaskets, flanges and cuffs must be purchased separately. Be sure to be original, otherwise there will be drips.
When calculating, you must remember that the device pumps 500 m³ of air per hour, so the minimum area of the room in which the Huch EnTEC VARIO is installed must be at least 20 m², with a ceiling height of 3 meters or more.
2. NIBE F1155-6 EXP (Sweden) – from RUB 355,161.
The model is declared as “intelligent” equipment, with automatic adjustment to the needs of the object. An inverter power supply circuit for the compressor has been introduced, making it possible to adjust the output power.
The presence of such a function with a small number of consumers (water points, heating radiators) makes heating a small house more profitable than in the case of a conventional, non-inverter HP (which does not have a soft start of the compressor and the output power is not regulated). Because at NIBE, at low power values, the heating elements are rarely turned on, and the heat pump’s own maximum consumption is no more than 2 kW.
In a small facility, the noise (47 dB) is not acceptable. The optimal installation option is a separate room. Place the harness on walls not adjacent to the rest rooms.
3. Fujitsu WSYA100DD6 (Japan) – from RUB 524,640.
“Out of the box” only works for heating in one circuit. An optional kit for connecting a second circuit is available, with the possibility of independent configuration for each. But the heat pump itself is designed for heating a room up to 100 m², with a ceiling height of no more than 3 meters.
The list of advantages includes small dimensions, operation from a household power supply, adjustment of the output temperature from 8 to 55 °C, which, according to the manufacturer’s plan, should somehow affect the comfort and accuracy of control of connected systems.
But everything was canceled out by low power. In our climate, heating the declared 100 m², the device will work for wear. This is confirmed by the device’s frequent transitions to “emergency” mode, with the pump turning off and errors on the display. The case is not guaranteed. Fixed by restarting the equipment.
“Accidents” affect energy consumption. Because when the compressor stops, the heating element comes into operation. Therefore, the joint connection of CO and underfloor heating (or DHW) circuits is permissible in a facility with an area of no more than 70 m².
Equipment for heating systems of standard cottages for permanent residence
Geothermal, air and water (removing thermal energy from groundwater) devices are presented here. The declared output power (at least 8 kW) is enough to provide heat to all consumer systems of country (and permanent residence) houses. Many heat pumps in this category have a cooling mode. The implemented inverter power circuits are responsible for the smooth start of the compressor; due to its smooth operation, the delta (temperature difference) of the coolant is reduced. The optimal operating mode of the circuit is maintained (without unnecessary overheating and cooling). This allows you to reduce power consumption in all operating modes of the HP. The greatest economic effect is in air-to-air devices.
4. Vaillant geoTHERM VWW 61/3 (Germany) – from RUB 408,219.
The use of well water as the primary coolant (VWW only) made it possible to simplify the design and reduce the price of the HP without loss of performance.
The device is characterized by low power consumption in the main operating mode and low noise level.
The downside of Vaillant is its demands on water (there are known cases of damage to the supply line and heat exchanger by iron and manganese compounds); work with salt-containing waters should be avoided. The situation is not guaranteed, but if the installation was carried out by service center specialists, then there is someone to file a claim with.
A dry, frost-free room with a volume of at least 6.1 m³ (2.44 m² with a ceiling of 2.5 m) is required. Dropping under the pump is not a defect (condensation is allowed to drain from the surfaces of insulated circuits).
5. LG Therma V AH-W096A0 (Korea) – from RUB 275,000.
Air-to-water heat pump. The device consists of 2 modules: the outer one takes thermal energy from the air masses, the inner one transforms and transfers it to the heating system.
The main advantage is versatility. Can be configured for both heating and cooling the object.
The disadvantage of this LG Therma series is that its (and the entire line’s) potential is not enough for the needs of a cottage with an area of more than 200 m².
An important point: the working units of a two-component system cannot be spaced more than 50 m horizontally and 30 m vertically.
6. STIEBEL ELTRON WPF 10MS (Germany) – from RUB 323,300.
The WPF 10MS model is the most powerful of the STIEBEL ELTRON heat pumps.
Among the advantages are an automatically adjustable heating mode and the ability to connect 6 devices into a cascade (this is a parallel or serial connection of devices to increase flow, pressure or organize an emergency reserve) system with a power of up to 60 kW.
The downside is that organizing a powerful electrical network for simultaneous connection of 6 such devices is only possible with the permission of the local branch of Rostechnadzor.
There is a peculiarity in setting the modes: after making the necessary adjustments to the program, you should wait until the control lamp goes out. Otherwise, after closing the lid, the system will return to the original settings.
7. Daikin EGSQH10S18A9W (Japan) – from RUB 1,607,830.
A powerful device for simultaneous provision of heat from CO, DHW and heated floors of a residential building with an area of up to 130 m².
Programmable and user-controlled modes; All serviced circuits are controlled within the specified parameters; there is a built-in storage tank (for DHW needs) of 180 liters and auxiliary heaters.
Among the shortcomings is the impressive potential, which will not be fully utilized in a house of 130 m²; a price due to which the payback period is extended indefinitely; automatic adaptation to external climatic conditions not implemented in the basic configuration. Environmental thermistors (thermal resistors) are optional. That is, when the external temperature changes, it is proposed to adjust the operating mode manually.
Equipment for objects with high heat consumption
To fully meet the thermal energy needs of residential and commercial buildings with an area of more than 200 m². Remote control, cascade operation, interaction with recuperators and solar systems - expand the user’s capabilities in creating a comfortable temperature.
8. WATERKOTTE EcoTouch DS 5027.5 Ai (Germany) – from RUB 708,521.
The DS 5027.5 Ai modification is the most powerful in the EcoTouch line. Stably warms up the heating circuit coolant and provides thermal energy to the hot water supply system in rooms up to 280 m².
Scroll (the most productive existing) compressor; adjusting the coolant flow rate allows you to obtain stable output temperature readings; color display; Russified menu; neat appearance and low noise level. Every detail is for comfortable use.
When the water points are actively used, the heating elements are turned on, causing energy consumption to increase by 6 kW/h.
9. DANFOSS DHP-R ECO 42 (Sweden) – from RUB 1,180,453.
Powerful enough equipment to provide thermal energy to the hot water supply system and heating circuits of a multi-level cottage with permanent residence.
Instead of an additional heater for DHW, the flow of hot water from the heating circuit supply is used here. By passing already hot water through the desuperheater, the heat pump heats the water in the additional DHW heat exchanger to 90 °C. A stable temperature in the CO and DHW tank is maintained by automatically adjusting the speed of the circulation pumps. Suitable for cascade connection (up to 8 TN).
There are no heating elements for the heating circuit. Additional resources are taken from any combined boiler - the control unit will take from it as much heat as is required in a particular case.
When calculating the space for installing a heat pump, it is necessary to leave a gap of 300 mm between the wall and the rear surface of the device (for ease of control and maintenance of communications).
10. Viessmann Vitocal 300-G WWC 110 (Germany) – from RUB 630,125.
Groundwater serves as the primary coolant. Hence the constant temperature on the first heat exchanger and the highest COP coefficient.
Among the advantages are a low-power auxiliary electric heater on the primary circuit and a proprietary controller (essentially a wireless remote control) for remote control.
Minus - the performance of the circulation pump, the condition of the main line and the primary circuit heat exchanger depend on the quality of the groundwater being distilled. Filtering is required.
Groundwater analysis will help eliminate the occurrence of difficult-to-solve problems with expensive equipment. Which should be done before purchasing a water-to-water heat pump.
Editor's Choice
Many years of experience in the production and operation of heat pumps in Northern Europe allowed our compatriots to narrow down the search area for the most profitable way to heat their home. Real options exist for any request.
Do you need to provide heat to the domestic hot water circuit or the heating system of a residential building up to 80 - 100 m²? Consider the potential NIBE F1155– its “intelligent” filling saves money without compromising heat supply.
A stable temperature in the underfloor heating, CO, and DHW circuits of a cottage of 130 m² will be ensured – a DHW heat exchanger (180 liters) is used here.
Produces a constant heat flow simultaneously for all consumers. The ability to create a cascade of 8 HP allows you to provide heat to an object with an area of at least 3,000 m².
Each of these models is not an absolute, but a basic option. If you have found a suitable TN, look through the entire line, study the optional offers. There is a wide range of equipment; there is a risk of missing your ideal option.
The article helped you find a profitable heating option, or you need additional information - write in the comments. We respond immediately.
Heating equipment, which uses quite expensive types of energy carriers such as gas, electricity, solid and liquid fuels, has relatively recently had a worthy alternative - a water-to-water heat pump. For the operation of such equipment, which is just beginning to gain popularity in Russia, inexhaustible energy sources characterized by low potential are needed. In this case, thermal energy can be extracted from almost any water source, which can be natural and artificial reservoirs, wells, wells, etc. If the calculation and installation of such a pumping unit is carried out correctly, then it is capable of providing heating for both residential and industrial buildings throughout the winter period.
Structural elements and operating principle
The principle of operation of the heat pumps under consideration for heating a house resembles the principle of operation of refrigeration equipment, only in reverse. If a refrigeration unit removes some of the heat from its internal chamber to the outside, thereby lowering its temperature, then the work of the heat pump is to cool the environment and heat the coolant that moves through the pipes of the heating system. Air-water and ground-water heat pumps operate on the same principle, which also use energy from low-potential sources to heat residential and industrial premises.
The design diagram of a water-to-water heat pump, which is the most productive among devices using low-potential energy sources, assumes the presence of such elements as:
- the outer circuit along which water moves, pumped from a water source;
- an internal circuit through which the refrigerant moves through the pipeline;
- an evaporator in which the refrigerant is converted into gas;
- a condenser in which the gaseous refrigerant becomes a liquid again;
- a compressor designed to increase the pressure of a refrigerant gas before it enters the condenser.
Thus, there is nothing complicated in the design of a water-to-water heat pump. If there is a natural or artificial reservoir near the house, then to heat the building it is best to use a water-to-water heat pump, the operating principle and design features of which are as follows.
- The circuit, which is the primary heat exchanger through which antifreeze circulates, is located at the bottom of the reservoir. In this case, the depth at which the primary heat exchanger is installed must be below the freezing level of the reservoir. Antifreeze, passing through the primary circuit, is heated to a temperature of 6–8°, and then supplied to the heat exchanger, giving off heat to its walls. The task of antifreeze circulating through the primary circuit is to transfer the heat energy of water to the refrigerant (freon).
- In the event that the heat pump operation scheme involves the intake and transfer of thermal energy from water pumped from an underground well, the antifreeze circuit is not used. Water from the well is passed through a special pipe through the heat exchanger chamber, where it transfers its thermal energy to the refrigerant.
- The heat exchanger for heat pumps is the most important element of their design. This is a device consisting of two modules - an evaporator and a condenser. In the evaporator, freon, supplied through a capillary tube, begins to expand and turns into gas. When gaseous freon comes into contact with the walls of the heat exchanger, low-grade thermal energy is transferred to the refrigerant. Freon charged with such energy is supplied to the compressor.
- The compressor compresses freon gas, causing the temperature of the refrigerant to increase. After compression in the compressor chamber, the freon enters another module of the heat exchanger - the condenser.
- In the condenser, gaseous freon again turns into liquid, and the thermal energy accumulated by it is transferred to the walls of the container in which the coolant is located. Entering the chamber of the second heat exchanger module, freon, which is in a gaseous state, condenses on the walls of the storage tank, imparts thermal energy to them, which is then transferred to the water located in such a chamber. If, at the exit of the evaporator, freon has a temperature of 6–8 degrees Celsius, then at the entrance to the condenser of a water-to-water heat pump, thanks to the above-described principle of operation of such a device, its value reaches 40–70 degrees Celsius.
Thus, the principle of operation of a heat pump is based on the fact that the refrigerant, when transitioning into a gaseous state, takes thermal energy from water, and when transitioning to a liquid state in the condenser, it releases the accumulated energy to the liquid medium - the coolant of the heating system.
Air-water and ground-water heat pumps operate on exactly the same principle; the only difference is in the type of source used to produce low-potential thermal energy. In other words, the heat pump has one operating principle that does not vary depending on the type or model of the device.
How efficiently the heat pump heats the heating system coolant is largely determined by fluctuations in the temperature of the water, a source of low-potential energy. Such devices demonstrate high efficiency when working with water from wells, where the temperature of the liquid medium throughout the year is in the range of 7–12 degrees Celsius.
The water-to-water pump is one of the ground-based types of heat pumps
The operating principle of a water-to-water heat pump, which ensures the high efficiency of this equipment, allows the use of such devices to equip heating systems of residential and industrial buildings not only in regions with warm winters, but also in the northern regions.
In order for the heat pump, the operation scheme of which is described above, to demonstrate high efficiency, you should know how to choose the right equipment. It is highly advisable that the selection of a water-to-water heat pump (as well as “air-to-water” and “earth-to-water”) is carried out with the participation of a qualified and experienced specialist.
When choosing a heat pump for water heating, the following parameters of such equipment are taken into account:
- productivity, which determines the area of the building the heating of which the pump can provide;
- the brand under which the equipment was manufactured (this parameter must be taken into account because serious companies, whose products have already been appreciated by many consumers, pay serious attention to both the reliability and functionality of the models they produce);
- the cost of both the selected equipment and its installation.
When choosing heat pumps water-to-water, air-to-water, earth-to-water, it is recommended to pay attention to the availability of additional options for such equipment. This includes, in particular, the following opportunities:
- control the operation of equipment in automatic mode (heat pumps operating in this mode due to a special controller allow you to create comfortable living conditions in the building they serve; changing operating parameters and other actions to control heat pumps that are equipped with a controller can be performed using a mobile device or remote control );
- using equipment for heating water in a hot water supply system (pay attention to this option because in some (especially old) models of heat pumps, the collector of which is installed in open reservoirs, it is not available).
Calculation of equipment power: implementation rules
Before you begin choosing a specific heat pump model, you need to develop a design for the heating system that such equipment will serve, as well as calculate its power. Such calculations are necessary in order to determine the actual thermal energy demand of a building with certain parameters. In this case, it is necessary to take into account the heat losses in such a building, as well as the presence of a hot water supply circuit in it.
For a water-to-water heat pump, power calculation is performed using the following method.
- First, determine the total area of the building for heating which the purchased heat pump will be used.
- Having determined the area of the building, you can calculate the power of the heat pump capable of providing heating. When performing this calculation, they adhere to the following rule: for 10 sq. m of building area requires 0.7 kilowatts of heat pump power.
- If the heat pump will also be used to ensure the functioning of the domestic hot water system, then 15–20% is added to the obtained value of its power.
Calculation of heat pump power, carried out according to the above described method, is relevant for buildings in which the ceiling height does not exceed 2.7 meters. More accurate calculations that take into account all the features of buildings that are to be heated using a heat pump are performed by employees of specialized organizations.
For an air-to-water heat pump, the power calculation is performed using a similar method, but taking into account some nuances.
How to make a heat pump yourself
Having a good understanding of how a water-to-water heat pump works, you can make such a device with your own hands. In fact, a homemade heat pump is a set of ready-made technical devices, correctly selected and connected in a certain sequence. In order for a home-made heat pump to demonstrate high efficiency and not cause problems during operation, it is necessary to perform a preliminary calculation of its main parameters. To do this, you can use the appropriate programs and online calculators on the websites of manufacturers of such equipment or contact specialized specialists.
So, in order to make a heat pump with your own hands, you need to select its equipment elements according to pre-calculated parameters and perform their correct installation.
Compressor
A compressor for a heat pump made by yourself can be taken from an old refrigerator or split system, paying attention to the power of such a device. The advantage of using compressors from split systems is the low noise level created during their operation.
Capacitor
As a condenser for a homemade heat pump, you can use a coil dismantled from an old refrigerator. Some people make it themselves using plumbing or a special refrigeration pipe. As a container in which to place the condenser coil, you can take a stainless steel tank with a volume of approximately 120 liters. To place a coil in such a tank, it is first cut into two halves, and then, when the installation of the coil is completed, it is welded.
It is very important to calculate its area before choosing or making your own coil. To do this you need the following formula:
P3 = MT/0.8PT
The parameters used in this formula are:
- MT – power of heat generated by the heat pump (kW);
- PT is the difference between the temperatures at the inlet and outlet of the heat pump.
To prevent air bubbles from being created in the heat pump condenser from the refrigerator, the inlet to the coil should be located in the upper part of the container, and the outlet from it should be located in the lower part.
Evaporator
As a container for the evaporator, you can use a simple plastic barrel with a capacity of 127 liters with a wide neck. To create a coil, the area of which is determined in the same way as for a condenser, a copper tube is also used. Home-made heat pumps typically use submersible evaporators, into which liquefied freon enters from below and turns into gas at the top of the coil.
When making a heat pump yourself, you should install the thermostat very carefully using soldering, since this element cannot be heated to a temperature exceeding 100 degrees Celsius.
To supply water to the elements of a self-made heat pump, as well as to drain it, ordinary sewer pipes are used.
Water-to-water heat pumps, when compared with air-to-water and ground-to-water devices, are simpler in design, but more efficient, which is why equipment of this type is most often manufactured independently.
Assembling a homemade heat pump and putting it into operation
To assemble and put into operation a homemade heat pump, you will need the following consumables and equipment:
- welding machine;
- vacuum pump (to test the entire system for vacuum);
- a cylinder with freon, refilling of which is carried out through a special valve (the installation of the valve in the system should be provided for in advance);
- temperature sensors that are installed on capillary pipes at the outlet of the entire system and at the outlet of the evaporator;
- starting relay, fuse, DIN rail and electrical panel.
All welding and threaded connections during assembly should be performed with the highest quality possible to ensure absolute tightness of the system through which freon will move.
In the event that water in an open reservoir acts as a source of low-potential energy, it is additionally necessary to manufacture a collector, the presence of which presupposes the operating principle of heat pumps of this type. If it is intended to use water from an underground source, it is necessary to drill two wells, into one of which the water will be discharged after it has passed through the entire system.
1, average rating: 5,00
out of 5)
Any owner of a private home strives to minimize the cost of heating their 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 other side of the coin: to obtain 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 3,500 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 HP). Let's consider several real working options, collected and tested by enthusiastic craftsmen in practice. Since the manufacture of a complex unit requires basic knowledge about refrigeration machines, let's start with the theory.
Features and principle of operation of TN
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;
- The HP is called a pump because it “pumps out” energy from sources of low-grade heat - ambient air, water or soil;
- the installation is powered exclusively by the electricity consumed by the compressor, fans, circulation pumps and control board;
- The operation of the device is based on the Carnot cycle, used in all refrigeration machines, for example, air conditioners and split systems.
Reference. Heat is contained in any substance whose temperature is above absolute zero (minus 273 degrees). Modern technologies make it possible to extract this energy from air with temperatures down to -30 °C, land and water - up to +2 °C.
The Carnot heat exchange cycle involves a working fluid - freon gas, boiling at sub-zero temperatures. Alternately evaporating and condensing in two heat exchangers, the refrigerant absorbs energy from the environment and transfers it inside the building. In general, the principle of operation of a heat pump is the same as that turned on for heating:
- While in the liquid phase, freon moves through the tubes of the external evaporator heat exchanger, as shown in the diagram. Receiving heat from air or water through metal walls, the refrigerant heats up, boils and evaporates.
- Then the gas enters the compressor, which pumps up the pressure to the calculated value. Its task is to raise the boiling point of the substance so that freon condenses at a higher temperature.
- Passing through the internal heat exchanger-condenser, the gas turns into liquid again and transfers the accumulated energy to the coolant (water) or room air directly.
- At the last stage, the liquid refrigerant 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 operating principle of a heat pump is similar to the operating principle of a split system Note. Conventional split systems and factory heat pumps have a common feature - the ability to transfer energy in both directions and operate in 2 modes - heating / cooling. The switching is implemented using a four-way reversing valve, which changes the direction of gas flow along the circuit.
Domestic air conditioners and heat pumps use various types of thermostatic valves that reduce the refrigerant pressure in front of the evaporator. In household split systems, the role of a regulator is played by a simple capillary device; pumps are equipped with an expensive thermostatic valve (TRV).
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 valves: capillary tube (photo on the left) and thermostatic valve (TRV) Types of installations
According to the generally accepted classification, heat pumps are divided into types according to the source of energy received and the type of coolant to which it is transferred:
Reference. Types of heat pumps are listed in order of increasing cost of equipment along with installation. Air plants are the cheapest, geothermal plants are expensive.
The main parameter characterizing a heat pump for heating a house is the efficiency coefficient COP, equal to the ratio between the energy received and the energy expended. For example, relatively inexpensive air heaters cannot boast of a high COP - 2.5...3.5. Let us explain: having spent 1 kW of electricity, the installation supplies 2.5-3.5 kW of heat to the home.
Methods for collecting 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. Productivity is a variable value, depending on many factors: the design of the heat exchange circuit, immersion depth, temperature and water flow.
Important point. Water heat pumps are not capable of heating the coolant to 60-90 °C without additional circuits. The normal water temperature from the heat pump is 35...40 degrees, boilers clearly win here. Hence the manufacturers' recommendation: connect the equipment to low-temperature heating - water.
Which TN is better to collect
Let us formulate the problem: you need to build a homemade 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 coefficient, our device will lose to factory models.
- Accordingly, it makes no sense to make a purely air HP; it is easier to use it in heating mode.
- To get real benefits, you need to manufacture 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 you can achieve 3-3.5.
- It will not be possible to do without underfloor heating circuits. Coolant heated to 30-35 degrees is incompatible with the radiator network, except in the southern regions.
Laying the external circuit of the HP to the reservoir Comment. Manufacturers claim: the inverter split system operates at street temperatures of minus 15-30 °C. In reality, heating efficiency is significantly reduced. According to homeowners, on frosty days the indoor unit supplies a barely warm air stream.
To implement the water version of the HP, certain conditions are required (optional):
- a pond 25-50 m from the home; at a greater distance, electricity consumption will increase significantly due to a powerful circulation pump;
- a well or well with a sufficient supply (debit) of water and a place for drainage (pit, second well, drainage ditch, sewer);
- prefabricated sewer (if they let you crash into it).
Groundwater flow is easy to calculate. In the process of heat extraction, a homemade heat pump will lower their temperature by 4-5 °C, from here the volume of the flow is determined through the heat capacity of the water. To obtain 1 kW of heat (we take the water temperature delta to be 5 degrees), you need to drive about 170 liters through the heat pump within 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. A similar heat water pump is suitable for a small country house of 30-40 m², preferably insulated.
Methods for selecting heat from geothermal heat pumps Assembling a geothermal system is more feasible, although the process is quite labor-intensive. We immediately reject the option of laying the pipe horizontally over an area at a depth of 1.5 m - you will have to shovel the entire area or pay money for the services of earth-moving equipment. The method of drilling wells is much simpler and cheaper to implement, with virtually no disturbance to the landscape.
The simplest heat pump from a window air conditioner
As you might guess, to manufacture a water-to-air heat pump you will need a window cooler in working condition. It is very advisable to buy a model equipped with a reversing valve and capable of 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 capacity and is equal to the sum of two parameters - performance plus the heat generated by the compressor With some luck, you won't even have to release the freon and resolder the pipes. How to convert an air conditioner into a heat pump:
Recommendation. If the heat exchanger cannot be placed in the tank without damaging the freon lines, try to evacuate the gas and cut the tubes at the required 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 plate.
Now all that remains is to launch a homemade HP and adjust the water flow, achieving maximum efficiency. Please note: the improvised heater uses a completely factory “filling”; you just moved the radiator from air to liquid. How the system works live, watch the video of the master craftsman:
Making a geothermal installation
If the previous option allows you to achieve approximately double savings, then even a homemade earthen 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 are no universal instructions with drawings. We will offer a working version, assembled and tested by a real home craftsman, although many things will have to be thought out and completed independently - it is difficult to put all the information about heat pumps in one publication.
Calculation of the soil circuit and pump heat exchangers
Following our own recommendations, we begin to calculate a geothermal pump with vertical U-shaped probes placed in wells. It is necessary to find out the total length of the external 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 zone. We will not spend on heating; we will determine the need for heat by area, taking into account thermal insulation - 7 kW.
If desired, you can arrange a horizontal collector, but then you will have to allocate a large area for excavation work Important clarification. Engineering calculations of heat pumps are quite complex and require highly qualified performers; entire books are devoted to this topic. The article provides simplified calculations taken from the practical experience of builders and craftsmen who love homemade products.
The intensity of heat exchange between the ground and the non-freezing liquid circulating along the circuit depends on the type of soil:
- 1 linear meter of a vertical probe immersed in underground water will receive about 80 W of heat;
- in rocky soils, the heat removal will be about 70 W/m;
- clayey soils saturated with moisture will deliver approximately 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 raw clay rock, you will need 7000 W divided by 50 W/m, we get a total probe depth of 140 m. Now the pipeline is distributed into wells 20 m deep, which you can drill with your own hands. A total of 7 drillings for 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 certain calculation formulas, which in most cases are incorrect. We will not take the liberty of recommending such methods and misleading you, but we will offer a cunning option:
- Contact any well-known manufacturer of plate heat exchangers, for example, 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 temperatures, heat load.
- The company’s specialist will make the necessary calculations and offer a suitable heat exchanger model. Among its characteristics you will find the main one - the exchange surface area.
Plate units are very effective, 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 given by the manufacturer by a safety factor of 1.1 and divide by the circumference of the pipe to obtain 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. Having selected a ½” copper tube 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
It is proposed to build the future heat pump on the basis of an outdoor unit of a split system of suitable power (indicated on the plate). Why is it better to use a used air conditioner:
- the device is already equipped with all components - compressor, throttle, receiver and starting electrics;
- homemade heat exchangers can be placed in the body of the refrigeration machine;
- There are convenient service ports for refilling freon.
Note. Users who are knowledgeable about 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 impractical to assemble a HP 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” up to 1 kW of heat, which is enough to heat one small room.
In addition to the external split unit, you will need the following materials:
- HDPE pipe Ø20 mm - to the earthen circuit;
- polyethylene fittings for assembling collectors and connecting to heat exchangers;
- circulation pumps – 2 pcs.;
- pressure gauges, 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 (needed to seal the ends of copper pipes).
Set of bushings for hermetic entry of copper tube A saline solution of water or antifreeze for heating – ethylene glycol – is used as an external coolant. You will also need a supply of freon, the brand of which is indicated on the nameplate of the split system.
Assembling the heat exchange block
Before starting installation work, the outdoor module must be disassembled - remove all covers, remove the fan and the large standard radiator. Disconnect 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 preserved.
Assembly procedure for the main VT block:
- Make a condenser and evaporator by inserting a copper tube inside a hose of the estimated length. At the ends, install tees to connect the ground and heating circuits; seal the protruding copper tubes using a special kit for the heating cable.
- Using a piece of plastic pipe Ø150-250 mm as a core, wind homemade two-pipe circuits and bring the ends in the right directions, as is done below in the video.
- Place and secure both shell-and-tube heat exchangers in place of the standard radiator, solder the copper tubes to the corresponding terminals. It is better to connect a “hot” heat exchanger-condenser to the service ports.
- Install factory sensors that measure coolant temperature. Insulate the bare sections of the tubes and the heat exchange devices themselves.
- Place thermometers and pressure gauges on the water lines.
Advice. If you plan to install the main unit outdoors, you need to take measures to prevent the oil from solidifying in the compressor. 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 inside 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.
Construction of the soil contour
At this stage, simple but labor-intensive excavation work and placement of probes in wells are performed. The latter can be done manually or by inviting a drilling machine. The distance between adjacent wells is at least 5 m. Further work order:
- Dig a shallow trench between the drillings to lay the supply pipes.
- Place 2 loops of polyethylene pipes into each hole and fill the holes with concrete.
- Bring the lines to the connection point and mount a common manifold using HDPE fittings.
- Insulate pipelines laid in the ground and fill them with soil.
On the left in the photo is lowering the probe into a plastic casing pipe, on the right is laying connections in the trench Important point. Before concreting and backfilling, be sure to check the tightness of the circuit. For example, connect an air compressor to the manifold, pump up a pressure of 3-4 bar and leave for several hours.
When connecting highways, follow the diagram presented below. Bends with taps will be needed when filling the system with brine or ethylene glycol. Lead the two main pipes from the collector to the heat pump and connect to the “cold” evaporator heat exchanger.
Air vents must be installed at the highest points of both water circuits; they are not shown in the diagram. Do not forget to install a pump 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 cold side lines, watch the video:
In a similar way, the condenser is connected to the house floor heating system. A mixing unit with a three-way valve does not need to be installed due to the low supply temperature. If you need to combine the transformer with other heat sources (solar collectors, boilers), use multiple terminals.
Refueling and starting the system
After installing and connecting the unit to the electrical network, an important stage begins - filling the system with refrigerant. A pitfall awaits here: you don’t know how much freon you need to charge, because the volume of the main circuit has increased significantly due to the installation of a homemade condenser with an evaporator.
The issue is solved by the filling method based on the pressure and overheating temperature of the refrigerant, measured at the compressor inlet (freon is supplied there in a gaseous state). Detailed instructions for filling out the temperature measurement method are set out in.
The second part of the video describes how to fill the system with R22 freon based on the pressure and superheat temperature of the refrigerant:
Upon completion of refueling, turn on both circulation pumps to first speed and start the compressor. Monitor the temperature of the brine and internal coolant using thermometers. During the warm-up stage, the lines with the refrigerant may freeze, and subsequently the frost should melt.
Conclusion
Making and running a geothermal heat pump with your own hands is very difficult. It will probably require repeated improvements, bug fixes, and tweaks. As a rule, most problems with homemade heat pumps occur due to improper assembly or filling of the main heat exchange circuit. If the unit immediately fails (the automatic safety system has tripped) or does not heat the coolant, it is worth calling a refrigeration equipment technician - he will carry out diagnostics and point out any mistakes made.
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