Types of heat pumps for home heating. How to make a ground source heat pump from an air conditioner Calculation of a heat pump for hot water supply

Types of designs of heat pumps

The type of HP is usually denoted by a phrase indicating the source medium and the heat carrier of the heating system.

There are the following varieties:

• TN "air - air";
• TN "air - water";
• TN "soil - water";
• TN "water - water".

The very first option is a conventional split system operating in heating mode. The evaporator is mounted on the street, and a block with a condenser is installed inside the house. The latter is blown by a fan, due to which a warm air mass is supplied to the room.

If such a system is equipped with a special heat exchanger with branch pipes, an air-to-water heat pump will be obtained. It is connected to the water heating system.

An air-to-air or air-to-water HP evaporator can be placed not on the street, but in the exhaust ventilation duct (it must be forced). In this case, the efficiency of HP will be increased several times.

Heat pumps of the "water - water" and "soil - water" types use the so-called external heat exchanger or, as it is also called, a collector to extract heat.

Schematic diagram of the heat pump

This is a long looped pipe, usually plastic, through which a liquid medium circulates, washing the evaporator. Both types of HP are the same device: in one case, the collector is immersed to the bottom of a surface reservoir, and in the second, to the ground. The condenser of such a HP is located in a heat exchanger connected to a water heating system.

Connecting a HP according to the "water - water" scheme is much less laborious than "soil - water", since there is no need for earthworks. At the bottom of the reservoir, the pipe is laid in the form of a spiral. Of course, only such a body of water is suitable for this scheme, which does not freeze to the bottom in winter.

It is time to study foreign experience in detail

Almost everyone already knows about heat pumps capable of extracting ambient heat for heating buildings, and if until recently a potential customer, as a rule, asked a bewildered question “how is this possible?”, Now the question “how is it right” is increasingly heard. do?".

It is not easy to answer this question.

In search of an answer to the numerous questions that inevitably arise when trying to design heating systems with heat pumps, it is advisable to refer to the experience of specialists from those countries where heat pumps based on ground heat exchangers have been used for a long time.

A visit* to the American exhibition AHR EXPO-2008, which was undertaken mainly to obtain information on the methods of engineering calculations of ground heat exchangers, did not bring direct results in this direction, but a book was sold at the ASHRAE exhibition stand, some of the provisions of which served as the basis for this publications.

It should be said right away that the transfer of American methods to domestic soil is not an easy task. Americans do not do things the way they do in Europe. Only they measure time in the same units as we do. All other units of measurement are purely American, or rather, British. The Americans were especially unlucky with the heat flux, which can be measured both in British thermal units per unit of time, and in tons of cooling, which were probably invented in America.

The main problem, however, was not the technical inconvenience of recalculating the units of measurement accepted in the United States, which one can eventually get used to, but the absence in the mentioned book of a clear methodological basis for constructing a calculation algorithm. Too much space is given to routine and well-known calculation methods, while some important provisions remain completely undisclosed.

In particular, such physically related initial data for the calculation of vertical ground heat exchangers, as the temperature of the liquid circulating in the heat exchanger and the heat pump conversion coefficient, cannot be set arbitrarily, and before proceeding with calculations related to unsteady heat transfer in the soil, it is necessary to determine the dependencies connecting these options.

The criterion for the efficiency of a heat pump is the conversion factor?, the value of which is determined by the ratio of its thermal power to the power of the compressor electric drive. This value is a function of the boiling temperatures in the evaporator t u and condensation t k , and in relation to heat pumps "water-water" we can talk about the temperatures of the liquid at the outlet of the evaporator t 2I and at the outlet of the condenser t 2 K:

? \u003d? (t 2I, t 2 K). (1)

An analysis of the catalog characteristics of serial refrigeration machines and water-to-water heat pumps made it possible to display this function in the form of a diagram (Fig. 1).

Using the diagram, it is easy to determine the parameters of the heat pump at the very initial stages of design. It is obvious, for example, that if the heating system connected to the heat pump is designed to supply a heating medium with a flow temperature of 50°C, then the maximum possible conversion factor of the heat pump will be about 3.5. At the same time, the temperature of the glycol at the outlet of the evaporator should not be lower than +3°C, which means that an expensive ground heat exchanger will be required.

At the same time, if the house is heated by underfloor heating, a coolant with a temperature of 35°C will enter the heating system from the heat pump condenser. In this case, the heat pump can work more efficiently, for example, with a conversion factor of 4.3, if the temperature of the cooled glycol in the evaporator is around -2°C.

Using Excel spreadsheets, you can express the function (1) as an equation:

0.1729 (41.5 + t 2I - 0.015t 2I t 2 K - 0.437 t 2 K (2)

If, with the desired conversion factor and a given value of the coolant temperature in the heating system powered by a heat pump, it is necessary to determine the temperature of the liquid cooled in the evaporator, then equation (2) can be represented as:

It is possible to choose the heat carrier temperature in the heating system for the given values ​​of the heat pump conversion coefficient and the liquid temperature at the outlet of the evaporator using the formula:

In formulas (2)…(4) temperatures are expressed in degrees Celsius.

Having determined these dependencies, we can now proceed directly to the American experience.

Methodology for calculating heat pumps

Of course, the process of selecting and calculating a heat pump is a technically very complex operation and depends on the individual characteristics of the object, but approximately it can be reduced to the following steps:

Heat losses through the building envelope (walls, ceilings, windows, doors) are determined. This can be done using the following ratio:

Qok \u003d S * (tin - tout) * (1 + Σ β) * n / Rt (W) where

tout - outside air temperature (°C);

tin – internal air temperature (°C);

S is the total area of ​​all enclosing structures (m2);

n - coefficient indicating the influence of the environment on the characteristics of the object. For premises in direct contact with the external environment through ceilings n=1; for objects with attic floors n=0.9; if the object is located above the basement n = 0.75;

β is the coefficient of additional heat loss, which depends on the type of building and its geographical location; β can vary from 0.05 to 0.27;

Rt - thermal resistance, is determined by the following expression:

Rt \u003d 1 / α int + Σ (δ i / λ i) + 1 / α out (m2 * ° С / W), where:

δ і / λі - calculated indicator of thermal conductivity of materials used in construction.

α nar - coefficient of thermal dissipation of the outer surfaces of enclosing structures (W / m2 * ° C);

α int - coefficient of thermal absorption of the internal surfaces of enclosing structures (W / m2 * ° C);

- The total heat loss of the structure is calculated according to the formula:

Qt.pot \u003d Qok + Qi - Qbp, where:

Qi - energy costs for heating the air entering the room through natural leaks;

Qbp ​​- heat release due to the functioning of household appliances and human activities.

2. Based on the data obtained, the annual consumption of thermal energy is calculated for each individual object:

Qyear = 24*0.63*Qt. sweat.*((d*(tin — tout.av.)/ (tin — tout.)) (kWh per year) where:

tout - outside air temperature;

tout.average - the arithmetic mean of the outdoor air temperature for the entire heating season;

d is the number of days of the heating period.

Qhv \u003d V * 17 (kW / h per year.) where:

V is the volume of daily heating of water up to 50 °C.

Then the total consumption of thermal energy is determined by the formula:

Q \u003d Qgw + Qyear (kW / h per year.)

Taking into account the obtained data, it will not be difficult to choose the most suitable heat pump for heating and hot water supply. Moreover, the calculated power is determined as. Qtn=1.1*Q, where:

Qtn=1.1*Q, where:

1.1 - correction factor indicating the possibility of increasing the load on the heat pump during the occurrence of critical temperatures.

After performing the calculation of heat pumps, you can choose the most suitable heat pump that can provide the required microclimate parameters in rooms with any technical characteristics. And given the possibility of integrating this system with a heated floor air conditioner, it can be noted not only its functionality, but also its high aesthetic value.

If you liked the material, I will be grateful if you recommend it to friends or leave a useful comment.

Types of heat pumps

Heat pumps are divided into three main types according to the source of low-grade energy:

• Air.
• Priming.
• Water - the source can be groundwater and reservoirs on the surface.

For water heating systems, which are more common, the following types of heat pumps are used:

"Air-to-water" - an air type heat pump that heats the building by taking air from outside through an external unit. It works on the principle of an air conditioner, only in reverse, converting the energy of the air into heat. Such a heat pump does not require large installation costs, it does not need to allocate a piece of land for it and, moreover, drill a well. However, the efficiency of operation at low temperatures (-25ºС) decreases and an additional source of thermal energy is required.

The "ground-water" device refers to geothermal and produces heat from the ground using a collector laid to a depth below the freezing of the soil. There is also a dependence on the area of ​​​​the site and the landscape, if the collector is located horizontally. For a vertical arrangement, a well will need to be drilled.

"Water-water" is installed where there is a reservoir or groundwater nearby. In the first case, the collector is laid on the bottom of the reservoir, in the second, a well is drilled or several, if the area of ​​​​the site allows. Sometimes the depth of groundwater is too great, so the cost of installing such a heat pump can be very high.

Each type of heat pump has its advantages and disadvantages, if the building is far from a body of water or the groundwater is too deep, then water-to-water will not work. "Air-water" will be relevant only in relatively warm regions, where the air temperature during the cold season does not fall below -25º C.

Method for calculating the power of a heat pump

In addition to determining the optimal energy source, it will be necessary to calculate the power of the heat pump required for heating. It depends on the amount of heat loss of the building. Let's calculate the power of a heat pump for heating a house using a specific example.

To do this, we use the formula Q=k*V*∆T, where

• Q is heat loss (kcal/hour). 1 kWh = 860 kcal/h;
• V is the volume of the house in m3 (we multiply the area by the height of the ceilings);
• ∆Т is the ratio of the minimum temperatures outside and inside the premises in the coldest period of the year, °С. From the internal tº we subtract the external one;
• k is the generalized heat transfer coefficient of the building. For a brick building with two layers of masonry k=1; for a well-insulated building k=0.6.

Thus, the calculation of the power of a heat pump for heating a brick house of 100 sq.m and a ceiling height of 2.5 m, with a difference in ttº from -30º outside to +20º inside, will be as follows:

Q \u003d (100x2.5) x (20- (-30)) x 1 \u003d 12500 kcal / hour

12500/860= 14.53 kW. That is, for a standard brick house with an area of ​​100 m2, you will need a 14-kilowatt device.

The consumer accepts the choice of the type and power of the heat pump based on a number of conditions:

• geographical features of the area (proximity of water bodies, the presence of groundwater, a free area for a collector);
• climate features (temperature);
• type and internal volume of the room;
• financial opportunities.

Considering all the above aspects, you will be able to make the best choice of equipment. For a more efficient and correct selection of a heat pump, it is better to contact specialists, they will be able to make more detailed calculations and provide the economic feasibility of installing equipment.

For a long time and very successfully, heat pumps have been used in household and industrial refrigerators and air conditioners.

Today, these devices began to be used to perform the function of the opposite nature - heating the home during the cold season.

Let's see how heat pumps are used for heating private houses and what you need to know in order to correctly calculate all its components.

Heat pump calculation example

We will select a heat pump for the heating system of a one-story house with a total area of ​​70 sq. m with a standard ceiling height (2.5 m), rational architecture and thermal insulation of enclosing structures that meet the requirements of modern building codes. For heating the 1st sq. m of such an object, according to generally accepted standards, you have to spend 100 W of heat. Thus, for heating the whole house you will need:

Q \u003d 70 x 100 \u003d 7000 W \u003d 7 kW of thermal energy.

We choose a heat pump brand "TeploDarom" (model L-024-WLC) with a heat output of W = 7.7 kW. The compressor of the unit consumes N = 2.5 kW of electricity.

Collector calculation

The soil in the area allotted for the construction of the collector is clayey, the groundwater level is high (we take the calorific value p = 35 W/m).

Collector power is determined by the formula:

Qk \u003d W - N \u003d 7.7 - 2.5 \u003d 5.2 kW.

L = 5200 / 35 = 148.5 m (approx.).

Based on the fact that laying a circuit longer than 100 m is irrational due to excessively high hydraulic resistance, we assume the following: the heat pump collector will consist of two circuits - 100 m and 50 m long.

The area of ​​​​the site that will need to be taken under the collector is determined by the formula:

Where A is the step between adjacent sections of the contour. We accept: A = 0.8 m.

Then S = 150 x 0.8 = 120 sq. m.

Payback of a heat pump

When it comes to how long a person will be able to return his money invested in something, it means how profitable the investment itself was. In the field of heating, everything is quite difficult, since we provide ourselves with comfort and warmth, and all systems are expensive, but in this case, you can look for an option that would return the money spent by reducing costs when using. And when you start looking for a suitable solution, you compare everything: a gas boiler, a heat pump or an electric boiler. We will analyze which system will pay off faster and more efficiently.

The concept of payback, in this case, the introduction of a heat pump to modernize the existing heat supply system, if simply, can be explained as follows:

There is one system - an individual gas boiler, which provides independent heating and hot water. There is a split-system type air conditioner that provides cold to one room. Installed 3 split systems in different rooms.

And there is a more economical advanced technology - a heat pump that will heat / cool houses and heat water in the right quantities for a house or apartment. It is necessary to determine how much the total cost of equipment and initial costs has changed, as well as to assess how much the annual costs of operating the selected types of equipment have decreased. And to determine how many years more expensive equipment will pay off with the resulting savings. Ideally, several proposed design solutions are compared and the most cost-effective one is selected.

We will carry out the calculation and find out what is the payback period of a heat pump in Ukraine

Consider a specific example

• House on 2 floors, well insulated, with a total area of ​​150 sq. m.
• Heat / heating distribution system: circuit 1 - underfloor heating, circuit 2 - radiators (or fan coil units).
• A gas boiler for heating and hot water supply (DHW), for example, 24kW, double-circuit, is installed.
• Air conditioning system from split systems for 3 rooms of the house.

Annual heating and water heating costs

1. The approximate cost of a boiler room with a 24 kW gas boiler (boiler, piping, wiring, tank, meter, installation) is about 1000 Euros. An air conditioning system (one split system) for such a house will cost about 800 euros. In total, with the arrangement of the boiler room, design work, connection to the gas pipeline network and installation work - 6100 euros.

1. Approximate cost of a Mycond heat pump with additional fan coil system, installation work and electrical connection is 6650 euros.

1. The growth of capital investments is: K2-K1 = 6650 - 6100 = 550 euros (or about 16500 UAH)
2. The reduction in operating costs is: C1-C2 = 27252 - 7644 = 19608 UAH.
3. Payback period Tokup. = 16500 / 19608 = 0.84 years!

Ease of use of the heat pump

Heat pumps are the most versatile, multifunctional and energy efficient equipment for heating a house, apartment, office or commercial facility.

An intelligent control system with weekly or daily programming, automatic switching of seasonal settings, maintaining the temperature in the home, economical modes, control of a slave boiler, boiler, circulation pumps, temperature control in two heating circuits, is the most advanced and advanced. Inverter control of the compressor, fan, pumps, allows maximum energy savings.

Heat pump operation during ground-water operation

Laying the collector in the ground can be done in three ways.

Horizontal option

Pipes are laid in trenches "snake" to a depth exceeding the depth of soil freezing (on average - from 1 to 1.5 m).

Such a collector will require a plot of land of a sufficiently large area, but any homeowner can build it - no skills other than the ability to work with a shovel will be needed.

It should, however, be taken into account that the construction of a heat exchanger by hand is a rather laborious process.

Vertical option

Collector pipes in the form of loops, having the shape of the letter “U”, are immersed in wells with a depth of 20 to 100 m. If necessary, several such wells can be built. After the pipes are installed, the wells are filled with cement mortar.

The advantage of a vertical collector is that a very small area is needed for its construction. However, there is no way to drill wells with a depth of more than 20 m on your own - you will have to hire a team of drillers.

Combined variant

This collector can be considered a variation of the horizontal one, but it will require much less space to build.

A round well is dug on the site with a depth of 2 m.

The heat exchanger pipes are laid in a spiral, so that the circuit is like a vertically mounted spring.

Upon completion of the installation work, the well falls asleep. As in the case of a horizontal heat exchanger, all the necessary amount of work can be done by hand.

The collector is filled with antifreeze - antifreeze or ethylene glycol solution. To ensure its circulation, a special pump crashes into the circuit. Having absorbed the heat of the soil, the antifreeze enters the evaporator, where heat exchange takes place between it and the refrigerant.

It should be taken into account that the unlimited extraction of heat from the soil, especially with a vertical collector, can lead to undesirable consequences for the geology and ecology of the site. Therefore, in the summer period, it is highly desirable to operate the HP of the "soil - water" type in the reverse mode - air conditioning.

The gas heating system has a lot of advantages and one of the main ones is the low cost of gas. How to equip home heating with gas, you will be prompted by the heating scheme of a private house with a gas boiler. Consider the design of the heating system and the requirements for replacement.

Read about the features of choosing solar panels for home heating in this topic.

Calculation of the horizontal collector of a heat pump

The efficiency of a horizontal collector depends on the temperature of the medium in which it is immersed, its thermal conductivity, as well as the area of ​​contact with the pipe surface. The calculation method is rather complicated, therefore, in most cases, averaged data are used.

It is believed that each meter of the heat exchanger provides the HP with the following heat output:

• 10 W - when buried in dry sandy or rocky soil;
• 20 W - in dry clay soil;
• 25 W - in wet clay soil;
• 35 W - in very damp clay soil.

Thus, to calculate the length of the collector (L), the required thermal power (Q) should be divided by the calorific value of the soil (p):

• The land above the collector is not built up, shaded, or planted with trees or bushes.
• The distance between adjacent turns of the spiral or sections of the "snake" is at least 0.7 m.

How heat pumps work

In any HP there is a working medium called a refrigerant. Usually freon acts in this capacity, less often - ammonia. The device itself consists of only three components:

The evaporator and condenser are two reservoirs that look like long curved tubes - coils. The condenser is connected at one end to the compressor outlet, and the evaporator to the inlet. The ends of the coils are joined and a pressure reducing valve is installed at the junction between them. The evaporator is in contact - directly or indirectly - with the source medium, while the condenser is in contact with the heating or DHW system.

How a heat pump works

The operation of the HP is based on the interdependence of the volume, pressure and temperature of the gas. Here is what happens inside the aggregate:

1. Ammonia, freon or other refrigerant, moving through the evaporator, heats up from the source medium, for example, to a temperature of +5 degrees.
2. After passing the evaporator, the gas reaches the compressor, which pumps it into the condenser.
3. The refrigerant pumped by the compressor is held in the condenser by a pressure reducing valve, so its pressure here is higher than in the evaporator. As you know, with increasing pressure, the temperature of any gas increases. This is exactly what happens to the refrigerant - it heats up to 60 - 70 degrees. Since the condenser is washed by the coolant circulating in the heating system, the latter is also heated.
4. Through the pressure reducing valve, the refrigerant is discharged in small portions into the evaporator, where its pressure drops again. The gas expands and cools, and since part of the internal energy was lost by it as a result of heat transfer at the previous stage, its temperature drops below the initial +5 degrees. Following the evaporator, it heats up again, then it is pumped into the condenser by the compressor - and so on in a circle. Scientifically, this process is called the Carnot cycle.

But HP still remains very profitable: for each kWh of electricity spent, it is possible to get from 3 to 5 kWh of heat.

Influence of initial data on the calculation result

Let us now use the mathematical model built in the course of calculations in order to trace the influence of various initial data on the final result of the calculation. It should be noted that the calculations performed on Excel allow such an analysis to be carried out very quickly.

To begin with, let's see how its thermal conductivity affects the value of the heat flux to the WGT from the ground.

home » Heating and ventilation in the country.

The use of alternative sources of energy today seems to be a priority. The transformation of wind, water and solar energy can significantly reduce the level of environmental pollution and save the financial resources necessary for the implementation of technological methods for generating energy. In this regard, the use of so-called heat pumps looks very promising. A heat pump is a device capable of transferring heat energy from the environment into a room. The heat pump calculation method, necessary formulas and coefficients are presented below.

�?sources of thermal energy

The sources of energy for heat pumps can be sunlight, heat from air, water and soil. The process is based on a physical process, due to which some substances (refrigerants) are able to boil at low temperatures. Under such conditions, the performance coefficient of heat pumps can reach 3 or even 5 units. This means that by spending 100 W of electricity to operate the pump, you can get 0.3-0.5 kW.

Thus, the geothermal pump is able to completely heat the house, however, on the condition that the temperature of the outdoor environment is not lower than the temperature of the calculated level. How to calculate a heat pump?

Technique for calculating the power of a heat pump

For this purpose, you can use a special online heat pump calculator or perform calculations manually. Before determining the pump power required for heating the house manually, it is necessary to determine the heat balance of the house. Regardless of the size of the house for which the calculation is made (calculation of a heat pump per 300m2 or per 100m2), the same formula is used:

• R is the heat loss / power of the house (kcal / hour);
• V is the volume of the house (length*width*height), m3;
• T - the highest difference between the temperatures outside the house and inside during the cold season, C;
• k is the average thermal conductivity of the building: k=3(4) is a house made of boards; k=2(3) - single-layer brick house; k=1(2) - brick house in two layers; k=0.6(1) - carefully insulated building.

A typical calculation of a heat pump assumes that in order to convert the obtained values ​​​​from kcal / h to kW / h, it is necessary to divide it by 860.

Pump Power Calculation Example

Calculation of a heat pump for heating a house using a specific example. Suppose that it is necessary to heat a building with an area of ​​100 sq.m.

To get its volume (V), you need to multiply its height by its length and width:

To find out T, you need to get the temperature difference. To do this, subtract the minimum outdoor temperatures from the minimum internal temperatures:

Let us take the heat loss of the building equal to k = 1, then the heat loss of the house will be calculated as follows:

The heat pump calculation program assumes that the heat consumption of the house must be converted into kW. We convert kcal / hour to kW:

• 12500 kcal / hour / 860 \u003d 14.53 kW.

Thus, for heating a house made of two-layer bricks with an area of ​​100 square meters, a heat pump of 14.5 kW is needed. If it is necessary to calculate the heat pump for 300m2, then the appropriate substitution is made in the formulas. This calculation takes into account the need for warm water needed for heating. To determine the right heat pump, you will need a heat pump calculation table showing the technical characteristics and performance of a particular model.

Heat pumps (HP), which allow the use of low-grade heat from the environment, are widely used abroad. Most of the large companies, manufacturers and developers of heat engineering equipment are already present in this market segment. The consumer, including the Russian one, is offered mass-produced devices, repeatedly proven solutions.

A deterrent to their spread is the need for a relatively large initial investment. Internet forums are actively discussing the experience of independent creation of heating systems with heat pumps, reducing the cost of certain works and increasing the efficiency of heat supply.

We selected selected passages from these discussions and tried to comment on them from the point of view of a professional equipment manufacturer.

Issue price

We read on the forum: The company proposed to supply a heat pump and equip the external circuit for 1.1 million rubles. The author independently purchased HP with hot water supply with a capacity of 8 kW for 93 thousand, drilled six wells at a cost of 500 rubles / m, installed pipes for the coolant, made their connection to the collector and HP.

The total cost of the work amounted to 170 thousand rubles. With an average annual payment for heating with electricity of 75 thousand rubles. all HP costs should pay off in three to four years.

The average specific cost of a turnkey organization of geothermal heating with HP in a house with an area of ​​200 m2 is about 5–7 thousand rubles.

rub./m2. The heat consuming system has a decisive influence on the efficiency of a heat pump heating system and must be managed with the lowest possible direct heating water temperatures.

For heating installations with HP, the rule is true: each degree of decrease in the temperature of direct network water saves energy consumption by 2.5%. The total cost consists of three parts: investment, cost of electricity, side costs. At the same time, side costs, which usually seem insignificant, should not be neglected: operating costs, which are difficult to predict when designing a system on your own, can amount to a significant amount.

Discuss "Heat pump with your own hands" on the forum

Technical finds

As a basis heat pump (HP) used a conventional split system.

Consuming electrical power of 1.3 kW, we get 6.5 kW of heat. The external unit of the air conditioner used in this case is placed in a plywood insulated box for the winter together with a car radiator, to which the coolant is supplied from the ground circuit.

In the summer and in the off-season, the walls of the box open.
In another case of achieving high efficiency, a HP was used from two circuits in a cascade, with two compressors. The condenser is made of steel tanks divided into two subcapacitors. In the first (“hot”), with a volume of 3 liters, there are two copper spirals from a pipe 10 m long.

The "cold" condenser also has a built-in spiral for forced cooling of compressors (the working fluid is antifreeze). System parameters: evaporator - steel tank (180 l); water comes from a well with a temperature of 15 ° C in a volume of 2 m3 / h, it is discharged into another well located 15 m from the water intake. The total electrical power consumed by the entire system is 4.2 kW. The temperature of the refrigerant (R22) at the inlet to the "hot" condenser is +110 °C, at the outlet - +55 °C.

At the entrance to the "cold" condenser - +55 °C, at the exit from it - +40 °C.

The implementation of the HP principle itself and the acquisition of the equipment necessary for this are not difficult. However, the coordination of the parameters of individual parts, their linking into a single installation can be difficult even for a specialized company.

After all, we are talking about the design and manufacture of technically complex equipment. Therefore, the successful (effective) operation of a self-made HP is more a matter of luck than an accurate engineering calculation: no one can guarantee that such a device will function well from the fifth, tenth or hundredth attempt of modernization.

Primary circuit

Independent drilling and arrangement of deep wells, which requires the use of special equipment, can cause many problems already at the initial stage: “We drilled for three days, repaired the machine for two days, raked heaps of clay for a day, made four probes of 25 m each.

The cost of wells is 650 rubles/m.

Selection and calculation of a heat pump

For the probe, pipes made of HDPE, designed for a pressure of 6 bar, are used. The pipes lowered into the well (there may be two or four, depending on the diameter of the well) are connected by a U-shaped tip.

At the same time, in winter conditions, to prevent destruction during installation, such pipes were preheated in the room. You can achieve greater savings by completing the outer contour yourself, but without drilling deep wells.

Options for its location: under the house or outside, in the ground.

In HP with vertical probes, the heat exchange system is installed in wells with a depth of 20 to 100 m. On average, a double U-probe from each meter of length provides approximately 55 W of thermal power.

The exact value depends on the geological and hydrogeological conditions, which are generally unknown to the heating installer. Therefore, the design and drilling of wells should be entrusted to an experienced and certified company to carry out the relevant work.

Groundwater as a heat source is usually suitable for realizing the monovalent operation of a heat pump. For reasons of economy, groundwater for water-to-water heat pumps up to 30 kW should not come from a depth of more than 15 m.

Fight for efficiency

When designing a heating system with a heat pump on your own, you can increase its efficiency by upgrading individual parts.

It is proposed, for example, to abandon the conventional heat accumulator, replacing it with a concrete screed, and to avoid unwanted temperature fluctuations at the supply by installing a mixing (damper) tank.

To control a home-made air-to-water HP, they use the automation of a conventional split system.
Opportunities are also being considered to obtain additional heat by experimenting with refrigerant, using compressors with a “floating” capacity, electronic thermostatic valves, combined heat exchangers, as well as by installing a solar collector in the evaporator circuit, an exhaust and wastewater heat exchanger, a kitchen “umbrella”, etc. .P.

The parameters of the heat exchanger determined by the design must necessarily be coordinated with other parameters of the HP.

These are calculated characteristics, the independent experimental selection of which is problematic. At the same time, using the concepts of “does not pull” and “works, but is inefficient”, it is very difficult to get into the area of ​​​​optimal parameters.
In heating systems with VTs, where power failure may not be detected in a timely manner, it is necessary to provide frost protection.

A heating water buffer tank is required to increase the heat pump's run-on time with low heat consumption. For air/water pumps, it is mandatory to ensure a minimum 10-minute overrun in defrost mode. Experiments with refrigerants are undesirable: at best, it will not be possible to achieve the intended goals, at worst, for example, when using propane, everything can end in an accident.

There are concerns...

When the ground source heat pump is running the earth contour zone will be strongly cooled and, in the end, you will get a small “ice age” on the site.

This can be avoided by digging the contour deeper so that there is a uniform compensation for the heat given off by the earth, or to reach powerful underground aquifers. It is also possible to prevent the appearance of "permafrost" by creating one or two loops of the external contour located in the air along the fence and connected for the summer with the part in the ground (for "recharging" the soil with heat).

Another variant of the location of the wells is also proposed - on the road near the site, and the air part of the external contour is looped with the wells.

Indeed, errors in determining the maximum possible heat removal and designing the external circuit lead not only to unsatisfactory operation of the HP, but can cause severe and deep freezing of the soil.

The so-called zebra (stripes of green grass alternating with bare, deeply frozen ground) is sometimes formed over the loops of a horizontal earth contour laid with violations of the necessary requirements. The temperature of the ground a meter from the surface can reach freezing even without ground heat recovery, at a depth of 2 m the minimum temperature is approximately 5 °C.

With increasing depth, it increases, but the heat flux from the soil surface also decreases. At the same time, the thawing of the earth in the spring is no longer guaranteed. The minimum depth for laying a horizontal circuit should be 1.2, the maximum - 1.5 m.
Self-construction of the primary circuit or following analogues without being tied to specific parameters of the well of the aquifer, river, lake (for water-to-water HP), soil, can lead to serious disruptions in the operation of the heat supply system.

Sergeev
Magazine "Aqua-Therm" №5 (63), 2011

How to make your own heat pump

Today there is no doubt that a heat pump for home heating is the most efficient of all.

This is the most expensive and complex tool. For this reason, many domestic masters themselves have solved this problem. But, given its great complexity, achieving positive results is not easy, it requires enthusiasm, patience and, in addition, a good study of theory.

Our article is intended for those who are taking the first step towards the introduction of such an alternative energy source as a heat pump, which they themselves have created.

The principle of operation of the device and operation

If you want to build an existing model of a heat pump, you cannot do without knowing the theory or better how this device works. First of all, I would like to mention that 300%, 500% and 1000% performances are myths or just a marketing ploy that should be ignored by the average user of physical laws.

Thus, a heat pump is a device that uses thermal energy in one place and moves it to another with a certain efficiency, which does not exceed 100%. Unlike boiler rooms, it does not produce heat by itself.

For example, domestic refrigerators and air conditioning systems based on the so-called Carnot cycle also use the heat pump principle for heating or hot water. The essence of this cycle is the movement of a substance (working fluid) along a closed system and a change in the state of aggregation from liquid to gaseous and vice versa.

During the transition, a huge amount of energy or absorption is released.

To explain in a more accessible language, we list the main elements that include a heat pump device:

• compressor;
• a heat exchanger in which the working medium passes into a gaseous state (evaporator);
• a heat exchanger in which the working medium is condensed (condenser);
• Expansion valve (reduction);
• means of control and automation;
• copper pipes.

A substance that boils at low temperatures - freon - appears as a working substance.

It circulates through the pipe as a liquid, first entering the evaporator. After interaction with a refrigerant from an external source (air, water, soil), the working fluid evaporates and continues to move in the form of a gas. At this point, the pressure in the system is low.

The whole cycle of the cycle reflects the principle diagram of the heat pump:

When the compressor is lowered, the freon moves under pressure to the second heat exchanger, where it must condense and transfer the received heat to water, which restores the current state.

In addition, the working fluid enters the expansion valve, the pressure drops again and continues the evaporation path. The cycle is over.

Heat pump installations for the home can produce refrigerant at a temperature of 55-60°C, which is enough to heat rooms with radiators or underfloor heating.

At the same time, the entire heating system uses electricity for these purposes:

• compressor adapter;
• rotation of rotating circuits of external and internal circuits;
• Means of automation and control.

It turned out that with the consumption of 1 kW of electricity, the operation of the heat pump can be moved from the outside up to 5 kW of thermal energy, so the efficiency of fiction is 500%.

Air-to-air heat pump

Theoretically, every medium with a temperature above absolute zero (minus 273 °C) has thermal energy.

Thus, it can be extracted, especially since it is not difficult to do it at an ambient temperature of minus 10-30 ° C.

For this purpose, an air heat pump is used, which removes heat from the external environment and moves inside a private house.

This is the most affordable way for equipment price and installation costs, it is also the least efficient. The more frost it is outside, the less heat you can get. The principle of operation of the system is shown in the figure:

The outdoor unit of an air heat pump is similar to the same unit of a separation system, but it does not have a compressor. The rest is only a flat heat exchanger and a fan, the task of which is to increase the intensity of the process by pumping a large amount of air through the plates.

Water/Water Heat Pump

A more efficient option is a water source heat pump.

It draws the closest water body from thermal energy if it is up to 100 m away from the house.

Heat pump power calculation

Another, more common way is to heat groundwater through a depression. In fact, the recesses require 2: one for pumping water, the other for dumping. Below are diagrams of heat pumps that work according to this principle:

There are several shades here.

The water from the hole must be cleaned before the heat exchanger is applied to it, and the hoses must be installed below the freezing depth of the soil. Another thing is that the contour of the lake bottom is filled with antifreeze (propylene glycol), which serves as an intermediary between water and refrigerant.

It is important.

The ability to provide a private house with thermal energy in this case depends on the productivity of the well and the amount of water in the pond. There are also possibilities to immerse the outer circuit in the running water of a river or a sewer septic tank.

There are also geothermal heat pumps, the principle of operation of which is no different from previous types of devices, but only heat from the soil at a depth where the temperature is always the same - plus 7 Q.

For this purpose, a horizontal contour of a tube, which occupies a large area, is buried in the ground, or geothermal probes are lowered into wells 25 m deep. In both cases, antifreeze is used as a coolant.

They believe that the operation of a heat pump, which produces heat from the ground, is the most stable and efficient. However, the purchase and installation of such equipment is very expensive, and local craftsmen rarely resort to this option.

How can I build a heat pump at home?

Since the thermodynamic calculation of a heat pump is self-employed for most domestic craftsmen, we will not present it here.

Our mission is to present several operating models so that any enthusiast can take one of them as a basis for creating your child.

It should be noted that the heat pump, designed and composed by his hands, would still be remote, if not for the production efforts and a lot of time for the vast majority of ordinary users.

The simplest heat pump from an old refrigerator is described in the article "Engineer" for 2006.

It is installed as a heater for a small room or greenhouse. By the way, no matter how strong a homemade refrigerator, even for a small house, it will not be enough to heat, but for one room - quite a bit. The solution is implemented in two ways: the internal automatic shutdown is disassembled and all devices are connected directly to continuous operation. In the first case, an old refrigerator is installed in the room, the design of the pump is shown in the figure:

Outside there are two air ducts and a glitch in the front door.

The air enters the freezer through the top channel, cools down and falls to the bottom air duct to increase the density. Then the body of the refrigerator comes out, moved by the upper current. The room is heated by a heat exchanger on the rear wall of the unit. Another way to make a DIY heat pump is as simple as building a refrigerator in an outside wall, as shown in the diagram:

The internal heater from the radiator can operate up to an outside temperature of minus 5 °C, but not below.

Heat pump from air conditioner

Modern split systems, especially inverters, successfully perform the functions of the same air-to-air heat pump.

Their problem is that the efficiency of work falls with the outside temperature, even the so-called winter set does not save.

Home craftsmen approached the issue: self-replacing heat pumps consisted of an air conditioner that heats the heat of running water from a well. In fact, from the air conditioner only a compressor, sometimes an indoor unit, which plays the role of a fan coil.

As a rule, the compressor can be purchased separately.

To heat water (condenser) it is necessary to replace the heat exchanger. A copper tube with a wall thickness of 1-1.2 mm, a length of 35 m, is wound in a coil with a diameter of 350-400 mm or a balloon. After that, the screws are fixed with a perforated corner, and then the whole structure is placed in a steel container with plumbing pipes.

The compressor from the split system is connected to the bottom inlet of the condenser, and the control valve is connected to the top.

Similarly, an evaporator is formed, as it will fit a simple plastic barrel. By the way, instead of homemade capacitive heat exchangers, you can use factory heat exchangers, but this will not be expensive.

The pump assembly itself is not too complicated, but it is important that we can solder the seams of copper pipes correctly and with high quality.

Even charging the Freon system will require master services, you will not become a special purchase of accessories. Next is the speed of regulation and start-up of the heat pump, which is not always improved. It may take a lot of work to achieve results.

conclusion

Of course, heating a home with a heat pump is a dream come true for many homeowners.

Unfortunately, the costs for factories are too high and they can deal with handmade production units. And then quite often enough only for hot water, heating does not work. If it was that simple, we had an indoor heat pump in every home, but it's still out of reach for the general public.

On the material pages: http://cotlix.com

Is a heat pump always efficient?

1. How much does it cost?

Many customers who know about a heat pump by hearsay have no idea of ​​its real cost, believing that the cost of installing it will be comparable to the cost of buying a conventional gas boiler.

In such cases, their desire to install a heat pump may disappear immediately after he knows what it will cost him approximately.

Of course, no one will be able to determine the exact price at the pre-design stage, because this price depends on many factors, the numerical values ​​of which will become known during the design process.

However, the order of numbers is already known, and therefore it is recommended to warn the customer at the very initial stage of design that as a result of the use of a heating heat pump, the cost of the building will increase by about 0.7 ...

$1.1 for every watt of heat output from a heat pump. It is clear that the larger the building, the lower this specific indicator.

After receiving this information, the customer, who always wants to know how much a square meter of a building under construction will cost him, will begin to calculate the increase in construction costs caused by the use of a heat pump.

If the thermal protection of the house is not properly implemented, and the specific heat output of the heating system, related to one square meter of the total area of ​​the house, is, for example, 80 W / m2, then the rise in price will be expressed in approximately the same number, but already in units of USD ./m2.

Thus, in a house of 400 m2 with a heating heat pump, you will have to invest additionally (80 x 400) about 30 thousand dollars. If this house is well insulated and the specific heat output of the heating system is increased to 40 W/m2, then the additional costs of installing a heat pump can be reduced by almost half.

Insulating a house is also not cheap, but insulation done during the construction process will save money over many years of operation, while an expensive heat pump will cost even more to operate.

Therefore, it is not recommended to install a heating heat pump in a poorly insulated house.

2. What determines the efficiency of operation

2.1. Conversion factor

The conversion factor of a heat pump is expressed through the ratio of the heat flux Q received in the condenser of thermal energy to the electric power N consumed in the compressor.

The larger the conversion factor, the more efficient the heat pump.

Typically, heating heat pumps operate with a conversion factor, the values ​​of which lie in the range of 3.5 ... 5. Heat pumps operating at a conversion factor of 3 or less are considered inefficient and such operation, if necessary, is permissible only for a relatively short period of time, despite the fact that three times more heat is received than is consumed by electrical energy. energy.

» The principle of calculation and selection of heat pumps

In fact, it is incorrect to compare the costs of thermal and electrical energy only by their quantity, because their qualitative characteristics are inadequate, and to generate one kilowatt-hour of electricity at a thermal power plant, three times more fuel is needed than to produce the same amount of heat in a boiler house.

On fig. 1 shows that with a heat pump conversion factor of 2.5, the amount of heat energy entering the house to heat it is less than the energy of the fuel that is burned in the power plant to obtain the amount of electricity needed for the heat pump. In this case, the heat pump cannot be considered energy-saving equipment, because its use leads to an increase in fuel consumption in the energy system.

Any boiler with an efficiency of more than 83% will be more energy efficient.

When operating a heat pump with a conversion factor equal to, for example, 5, it is possible to obtain much more heat than is contained in the fuel (Fig. 2).

Taking into account all these features of energy conversion in heat pumps, in December 2008 the European Parliament adopted the Directive on the Use of Renewable Energy Sources, which does not allow the use of heat pumps with a conversion factor equal to 2.875 and below.

The conversion factor value of a heat pump depends on the temperature difference between the boiling point of the refrigerant in the evaporator and its condensation in the condenser. The smaller this difference, the higher the conversion factor.

The boiling point depends on the temperature of the environment used as a heat source for the heat pump, and when designing a heating system with a heat pump, the engineer does not have the opportunity to change this temperature.

But, choosing the condensation temperature, the designer must set a sufficiently low temperature. Therefore, the coolant temperatures of 95-70 °C, common for water heating systems, are never used in systems with heat pumps.

The most economical in terms of energy consumption are heating systems, for example, systems with floor heating, in which water circulates at a temperature below 40 ° C.

The theoretical conversion factor of an ideal heat pump is calculated using the Carnot formula:

ε=T2 /(T1 – T2), (2)

where T1 is the condensation temperature;

T2 is the boiling point of the refrigerant expressed in degrees Kelvin.

If the heat pump were completely perfect, then at an evaporating temperature of +5°C (T2 = 278 K) and at a condensing temperature of 55°C (T1 = 358 K), it could work with a conversion factor of 5.56.

In fact, the conversion factor will be less, because there are no completely perfect machines, and the degree of deviation of the real conversion factor from the theoretically possible one depends on many factors.

These include the physical dimensions of the heat exchangers, the properties of the refrigerant, the features of the compression process in the compressor, and much more.

There are many formulas in the literature for calculating the conversion factor of a heat pump, but all of them are inaccurate, and it is difficult to use them in practical calculations, and it does not make sense, since in the complete catalogs of heat pump manufacturers you can always find the values ​​​​of thermal and electric power of any serial unit at various temperature conditions.

The ratio of these quantities is the conversion factor.

Knowing the boiling and condensing temperatures of the refrigerant is not as important for the designer of the heating system as having information about the temperatures of the coolant cooled in the evaporator or heated in the condenser. Therefore, in the catalogs of water-to-water heat pumps, the values ​​of thermal and electrical capacities of heat pumps are given taking into account precisely these temperatures.

As an example, Fig. 3 shows a graph compiled on the basis of an analysis of the catalog characteristics of one of the serial models of a heat pump.

The graph shows the dependence of the conversion factor on the temperatures of the coolants at the outlet of the evaporator and condenser.

Another graph (Fig. 4), built on the basis of the catalog characteristics of a specific model range of air-to-water heat pumps, reflects the dependence of the heat pump conversion factor on the coolant temperature at the condenser outlet and on the outside air temperature.

The conversion factor of a heat pump is the most important criterion for its energy efficiency, but it is important for the building owner to know how this efficiency will affect his financial costs.

And here tariffs will play a major role.

2.2. Energy tariffs

No matter how efficient a heat pump is, the degree of its attractiveness for the customer depends not so much on the degree of its technical perfection or usage pattern, but on the tariff policy of the state.

The cost of electrical energy required to operate a heat pump will be less than the cost of purchasing natural gas or thermal energy, which could be used for traditional heating systems, if the inequality is observed:

Tae<(ε /η).Тт, (3)

where Te is the tariff for electricity;

Тт is the tariff for one of the traditional energy carriers;

ε is the conversion factor of the heat pump;

η is the efficiency of a traditional heat generator.

In order to be able to apply formula 3, it is necessary that the tariffs Te and Tm be expressed in the same units of measurement. Usually the gas tariff is expressed in UAH/m3 and the heat tariff in UAH/Gcal, while the electricity tariffs are always expressed in UAH/kWh.

To be able to compare tariffs, it is convenient to use the following dependencies:

1 UAH/m3 = 0.106 UAH/kW. h;

100 UAH/Gcal = 0.086 UAH/kW. h.

Example 1

In a single-family house, the heating system receives heat from a gas boiler operating with an efficiency factor η = 0.9. Is it profitable to use a heat pump in this house, which will operate with a conversion factor of 3.5, if the current electricity tariff is 0.7 UAH / kW. h, and for gas - 1.5 UAH / m3?

Let's recalculate the gas tariff:

1.5 UAH/m3 = 1.5. 0.106 = 0.159 UAH/kW. h) and calculate the right side of inequality 3:

Let us now compare the left and right sides of inequality 3:

Since inequality 3 is not satisfied, replacing a gas boiler with a heat pump at the indicated tariffs is unprofitable and will lead to an increase in energy costs.

Example 2

It is expected that in a few years the gas tariff will double and amount to 3 UAH/m3, while the tariff for electricity will increase by 20% and amount to 0.84 UAH/kW. h.

Will the operation of the heat pump described in example 1 be profitable in the new conditions?

Yes is beneficial, because inequality 3 will hold:

(3,5 /0,9) . (3 . 0,106) = 1,24;

Example 3

In the school building, the heating system receives heat from the city heat network at a rate of 200 UAH / Gcal, and the heat supply organization adds 15% to the heat meter readings for unaccounted heat losses in the heat network section owned by the subscriber.

Will the school's costs for heat carriers decrease after installing a heat pump that will operate with a conversion factor of 3.2 if the electricity tariff is 0.25 UAH/kW. h?

Let's recalculate the tariff for thermal energy:

200 UAH / Gcal = 2. 0.086 = 0.172 UAH/kW. h

and calculate the right side of inequality 3, assuming that the additional 15% losses are adequate to the conditional value of efficiency η = 0.85:

0,25 < 0,648.

Inequality 3 is satisfied, which means that the school's costs for heat carriers will decrease after the installation of a heat pump.

Examples show that in the absence of tariff distortions, energy costs when using efficient heat pumps will be less than when using conventional heat sources.

But the customer is usually interested in whether the reduction in operating costs over time can compensate for the additional one-time costs associated with the purchase and installation of the heat pump, and, if so, how soon.

3. Payback period

The payback period for additional capital costs is determined, as a rule, as a result of a feasibility study performed on the basis of design studies of the facility where the heat pump is supposed to be used. But in this case, we are not talking about a specific object, and therefore the most general analysis is appropriate here, as a result of which the customer will be able to assess the possible payback period at the pre-design stage.

Savings in operating costs for energy carriers E, UAH / year, when using a heat pump can be calculated by the formula:

E \u003d q. (Тт/η -Те/ε), (4)

where q is the number of kW. hours of thermal energy required to heat the building during one heating period, and the meaning of the remaining symbols in the formula is the same as in inequality 3.

The value of q can be determined by the formula:

q=10-3 . 24. N. S/(tB - tH), (5)

where N is the thermal power, W, of the heating system;

S is the number of degrees per day of the heating period;

tB - tH - temperature difference between indoor and outdoor air.

Part of equation 5, namely 10-3. 24. S/(tB - tH) characterizes the climate of the region, and for Ukraine this value is close to 2.

For our most general analysis, it is acceptable not to specify this value, and then:

One-time capital costs K, UAH, for the purchase and installation of a heat pump in accordance with the recommendations of Section 2.1 can be preliminary estimated using the formula:

K \u003d 0.9. V. N,(7)

where V is the exchange rate, UAH/USD;

N - thermal power, W, of the heating system.

The simple payback period C, years, can be determined by the formula:

C \u003d K / E \u003d 0.9. V. N/, (8)

Substituting instead of q its approximate value from formula 6, we get:

C \u003d 0.45. V/(Tm/η-Te/ε), (9)

This formula for the approximate payback period of a heat pump is tied to its conversion factor and to purely economic indicators, namely tariffs and the hryvnia exchange rate.

Using this formula, we will determine the payback periods of some heat pumps using examples.

Example 4

Determine the approximate payback period for the heat pump from Example 2 if the exchange rate is 7.7 UAH/USD.

The payback period is calculated by formula 9:

C \u003d 0.45. 7.7 / (3. 1.06 / 0.9-0.84 / 3.5) \u003d 14.4 years.

Example 5

Determine the approximate payback period for the heat pump from Example 3 if the exchange rate is 6.5 UAH/USD.

C \u003d 0.45. 6.5 / (0.172 / 0.85-0.25 / 3.2) = 23.6 years.

Examples 4 and 5 show that payback periods were not very attractive for an investor, for whom a five-year return on investment is an extremely long period of time.

But a thoughtful investor with the help of the transformed formula 9 can solve the inverse problem:

Example 6

Despite the long payback period for the heat pump, the owner of the single-family house described in examples 1, 2 and 4, realizing that fuel prices are constantly rising, decided to determine at what gas tariff the payback period would not exceed 5 years, if all other the indicators from example 4 will remain unchanged.

The transformed formula 9 can be represented as:

(0.45 . V/C + Te/ε).

Substituting into it C = 5 and the initial data from example 4, we get:

TT \u003d 0.9. (0.45 . 7.7 / 5 + 0.84 / 3.5) = 0.839 UAH / kW. h = 7.9 UAH/m3.

The results of the calculation performed in example 6 are very revealing. Taking into account the hryvnia exchange rate, the resulting tariff value corresponds to a gas cost of about $1,000 per 1,000 m3.

Approximately at this price citizens of Denmark and many other European countries buy gas. The already mentioned thoughtful investor will quickly realize that European prices will come to Ukraine very soon, and, if the necessary funds are available, he will probably still decide to use a heat pump in his house.

4. Non-commercial benefit

Not only money sometimes determines the choice of a particular technical solution. If we talk about a heat pump, then at least three circumstances that are not directly related to commercial benefits can serve as a reason for a favorable attitude towards it.

The first of them is a higher degree of energy independence of the object.

One could talk here about autonomous heating, if the apologists for gas boilers had not appropriated this term completely unreasonably to systems tied to a gas pipeline.

In fact, completely autonomous heating systems do not exist, and even the so-called "passive" houses, insulated so carefully that internal heat emissions are sufficient to maintain a comfortable temperature inside them in winter, cannot be considered completely autonomous, because the heat sources in them are domestic equipment operating from the power supply system.

At the same time, a heat pump that uses the energy of the environment is able to provide a higher degree of energy independence of the building compared to a gas boiler that receives fuel from deposits located many thousands of kilometers from the consumer.

Of course, there remains dependence on the building's power supply system, but electrical energy, unlike natural gas, will exist until civilization disappears, and problems associated with the possibility of a temporary power outage can be eliminated, if necessary, by installing backup sources, for example, diesel generators .

Another non-commercial benefit from the use of a heat pump is the higher degree of comfort that can be created in the building where this equipment is installed, with which it is possible not only to heat rooms in winter, but also to cool them in summer.

However, in this case, the benefit from additional comfort can be expressed in monetary units. In buildings with air conditioning, the rise in price associated with the use of a heat pump can be determined by formula 7, if an additional reduction factor is introduced into it.

The great variety of air conditioning systems does not allow to unambiguously determine the value of this coefficient, but it can be assumed that in any case it will not exceed 0.6, and then the payback periods calculated by formula 9 will be much more attractive.

And finally, it is impossible not to mention such an important non-commercial factor as prestige. The heat pump has become fashionable in our time, and fans of modern fashion, including technological ones, as you know, are ready to spend any money to stay on the crest of the fashion wave.

One can only wish them good luck in this field, because their luck in this case will ideally fit into the implementation of the state strategy for the efficient use of energy.

In English-language publications, including those translated into Russian, the heat pump conversion coefficient is denoted by the English abbreviation COP -coefficient of performance, which literally means "performance coefficient".

Provided that the calorific value of natural gas is 8000 kcal/m3.

There is nothing surprising in the fact that Ukraine still lags behind Europe in the field of heat pumps.

It is not our inertia that is to blame for this lag. If there was cheap gas in Europe, heat pumps would still, like ours, remain the field of activity of a few enthusiasts.

http://ivik.donetsk.ua

Content:

Heat pump: principle of operation - features and types

1. Where does the pump get its heat from?
2. Heating system with heat pump
3. Approximate calculation of heat output
4. Types of heat pumps
5. Advantages of heat pumps
6. Some features of pump operation

Such a unit as a heat pump has a principle of operation similar to household appliances - a refrigerator and an air conditioner.

Approximately 80% of its power it borrows from the environment. The pump pumps heat from the street into the room. Its operation is similar to the principle of operation of a refrigerator, only the direction of heat transfer is different.

For example, to cool a bottle of water, people put it in the refrigerator, then the household appliance partially “takes” heat from this object and now, according to the law of conservation of energy, it must give it back.

But where? It's simple, for this the refrigerator has a radiator, usually located on its back wall. In turn, the radiator, heating up, gives off heat to the room in which it stands.

Thus, the refrigerator heats the room. To what extent it warms up, you can feel in small shops in the hot summer, when several refrigeration units are turned on.

And now a little fantasy.

Suppose that warm objects are constantly placed in the refrigerator, and it heats the room or it is placed in a window opening, the freezer door is opened to the outside, while the radiator is in the room. In the process of its work, the household appliance, cooling the air outside, will simultaneously transfer the thermal energy that is outside into the building. The principle of operation of a heat pump is exactly the same.

Where does the pump get heat from?

The heat pump operates due to the operation of natural low-grade sources of thermal energy, including:

• ambient air;
• reservoirs (rivers, lakes, seas);
• soil and ground artesian and thermal waters.

Heating system with heat pump

When a heat pump is used for heating, its principle of operation is based on integration into the heating system.

It consists of two circuits, to which a third is added, which is the design of the pump.

The coolant, which takes heat from the environment, circulates along the external circuit. It enters the pump evaporator and gives off approximately 4 -7 ° C to the refrigerant, despite the fact that its boiling point is -10 ° C.

The functional circuit of the heat pump consists of:

• evaporator;
• refrigerant;
• electric compressor;
• condenser;
• capillary;
• thermostatic control device.

The process of how a heat pump works is something like this:

• the refrigerant after boiling, moving through the pipeline, enters the compressor, which works with the help of electricity.

  This device compresses the refrigerant in the gaseous state to a high pressure, which causes its temperature to rise;

• hot gas enters another heat exchanger (condenser), in which the heat of the refrigerant is given off to the heat carrier circulating in the internal circuit of the heating system, or to the air in the room;
• cooling, the refrigerant passes into a liquid state, after which it passes through the capillary pressure reducing valve, losing pressure, and then again finds itself in the evaporator;
• thus the cycle is complete and the process is ready to repeat.

Approximate calculation of heat output

For an hour, 2.5-3 cubic meters of coolant passes through the pump through the external collector, which the earth is able to heat by ∆t = 5-7 ° C (read also: “It is important to know: how to think over the calculation of a heat pump”).

Q = (T1 - T2) x V, where:
V – coolant flow rate per hour (m3/h);
T1 - T2 - inlet and outlet temperature difference (°C) .

Types of heat pumps

Depending on the type of dissipated heat consumed, heat pumps are:

• ground-water - for their work in a water heating system, closed ground contours or geothermal probes located at a depth are used (for more details: "Geothermal heat pumps for heating: the principle of the system design");
• water-water - the principle of operation of a heat pump for heating a house in this case is based on the use of open wells for groundwater intake and discharge (read: "How to choose a water pump for heating").

  At the same time, the external circuit is not looped, and the heating system in the house is water;

• water-air - install external water circuits and use air-type heating structures;
• air-to-air - for their operation, they use the dissipated heat of the external air masses plus the air heating system of the house.

Advantages of heat pumps

1. Economy and efficiency.

   The principle of operation of the heat pumps shown in the photo is based not on the production of thermal energy, but on its transfer. Thus, the efficiency of the heat pump must be greater than unity. But how is this possible? In relation to the operation of heat pumps, a quantity is used, which is called the heat conversion coefficient, or abbreviated CTC. The characteristics of units of this type are compared precisely by this parameter. The physical meaning of the quantity is to determine the ratio between the amount of heat received and the energy spent to obtain it.

   For example, if the KPT coefficient is 4.8, this means that 1 kW of electricity consumed by the pump allows you to get 4.8 kW of heat, and free of charge by nature.

2. Universal universal application.

   In the absence of power lines available to consumers, the operation of the pump compressor is provided using a diesel drive. Since natural heat is everywhere, the principle of operation of this device allows you to use it everywhere.

3. Environmental friendliness. The principle of operation of a heat pump is based on low power consumption and the absence of combustion products.

   The refrigerant used by the unit does not contain chlorocarbons and is completely ozone safe.

4. Bidirectional mode of operation.

   House heating. House heating scheme with a heat pump

   During the heating period, the heat pump is able to heat the building, and in the summer to cool it. The heat taken from the premises can be used to provide the house with hot water, and if there is a pool, heat the water in it.

5. Safe operation. There are no dangerous processes in the operation of heat pumps - there is no open fire, and substances harmful to human health are not released.

   The coolant does not have a high temperature, which makes the device safe and at the same time useful in everyday life.

6. Automatic control of the space heating process.

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

Some features of pump operation

To ensure the efficient operation of the heat pump, a number of conditions must be met:

• the room must be well-insulated (heat loss cannot exceed 100 W / m²);
• a heat pump is beneficial to use for low-temperature heating systems.

  This criterion is met by a floor heating system, since its temperature is 35-40°C. CPT largely depends on the ratio between the temperature of the inlet and outlet circuits.

The principle of operation of heat pumps is to transfer heat, which makes it possible to obtain an energy conversion coefficient of 3 to 5.

In other words, every 1 kW of electricity used brings 3-5 kW of heat into the house.

Heat pump- a heat transfer device from a low-grade heat source (low temperature) to a consumer (coolant) at a higher temperature.

A thermodynamic heat pump is similar to a refrigeration machine.

However, if the main purpose of cooling is to produce cold, with the selection of heat from any scale evaporator, and the condenser dumping heat into the environment, v the heat pump image is rotated.

The condenser is a heat exchanger that generates heat for the consumer, while the evaporative heat exchanger has low potential heat: secondary energy sources and / or renewable energy sources.

The concept of heat pumps was developed in 1852 by the eminent British physicist and engineer William Thomson (Lord Kelvin) and the even more sophisticated and precise Austrian engineer Peter Ritter von Rittinger.

Peter Ritter von Rietinger is considered the inventor of the heat pump as he designed and installed the first known heat pump in 1855. But the practical use of the heat pump in the 1940s, when enthusiastic inventor Robert C. Weber (Robert C.

Webber) experimented with a freezer.

When Weber accidentally touched the hot tub at the exit of the chamber and found the heat released. The inventor thought about how to use this heat and decided to lay a pipe in the boiler to heat water.

If the heat pump is used to heat the house

As a result, Weber gave the family as much hot water as they could not physically use, while the heat from the heated water was released into the air.

This led to the idea that water and air could be heated from the same heat source.

Therefore, Weber improved his invention and began to drive hot water in a spiral (through a coil) and with the help of a small fan to distribute the heating system around the heating house.

Over time, Weber's idea was to "heat" heat from the ground, where the temperature did not change much during the flight. He put it in the copper pipes of the Earth, through which the Fron spread, which "collected" the warmth of the earth.

The gas thickened, it repaired the heat in the house and passed through the coil again to pick up the next piece of heat. In the air, he led the fan and settled throughout the house. The following year, Weber sold his old carbon furnace.

In the 1940s, the heat pump became known for its efficiency, but in the 1970s it came into being due to the emergence of global energy saving interest.

Types of heat pumps

Depending on the principle of operation, heat pumps are divided into compression and absorption.

The compression of a heat pump is always driven by mechanical energy (electricity) and an absorption heat pump can also be used as a heat source (using electricity or fuel).

Heat pumps are divided into:

1) geothermal energy(use of the heat of the earth, groundwater or underground groundwater);

2) antenna(the source of thermal energy is air);

3) using derivative (secondary) fever(e.g. central heating pipe).

Geothermal heat pump can be:

- closed (horizontal, vertical or water);

- open type;

- with direct heat exchange.

first Geothermal heat pump

Rice. second Air heat pump

Geothermal heat pumps They have such a device.

A) closed type :

— horizontally:

The collector is placed in rings or immersed in horizontal ditches below the freezing depth of the ground (typically 1.2 m or more).

This method is the most cost-effective for residential properties where there is no shortage of land for contours.

— vertical:

The collector is placed vertically in wells up to 200 m deep. This method is used in cases where the ground surface does not allow horizontal installation of the contour or the threat of damage to the landscape.

— water:

The collector has a hole or ring in the reservoir (lake, pond, river) below the freezing depth.

This is the cheapest option, but there are regional minimum depth and water tank requirements.

— with direct heat exchange(DX - short for English "direct exchange" - "direct exchange").

Unlike previous types, the heat pump compressor is supplied through copper pipes located:

— vertically in boreholes 30 m long and 80 mm in diameter;

— at an angle in cavities 15 m long and 80 mm in diameter;

— horizontally in the ground below the freezing depth.

The circulation of the refrigerant with the compressor of the heat pump and the transfer of freon heat directly through the wall of the copper pipe with increased thermal conductivity ensures high efficiency and reliability of the geothermal heating system.

b) open type :

Such a system uses water that circulates directly through the ground source heat pump system as an open cycle heat exchange fluid, which means that the water returns to the ground after passing through the system.

This option can only be put into practice if there is sufficient, relatively clean water available and provided that this method of using groundwater is not prohibited by law.

Rice. third Diagram of a compressor heat pump: 1 - capacitor; 2 - gas; 3 - evaporator; 4 - compressor

Industrial models of heat pumps are divided into eight types according to the type of coolant in the inlet and outlet circuits of the pump: "flow", "water-to-water", "air-to-water", "air-to-air", "water-to-air", air ”,“ freon-water ”,“ freon-air ”.

Heat pumps can use the heat of the air from the room when heating the supply air (recuperators).

first

Separating heat from air

The efficiency and choice of a particular source of thermal energy is highly dependent on climatic conditions, especially if the heat source is in the air.

In fact, this type is more commonly known as an air conditioner. There are tens of millions of such devices in hot countries. For the Nordic countries, winter heating is the most important. Air-to-air and air-to-air systems are also used in winter at temperatures down to minus 25 degrees, some models still operate down to -40 degrees. However, their efficiency is low, about 1.5 times higher than the cost of energy, and for the heating season it is on average 2.2 times higher than that of electric heaters.

In the case of heavy freezers, additional heating is used. When the capacity of the main heating system with heat pumps is insufficient, additional heat sources are switched on. Such a system is called dual.

2. Extraction of heat from rocks

Stone requires drilling a well at a sufficient depth (100-200 meters) or more of such wells. The U-shaped load falls into the hole with two contoured plastic pipes. The pipes are filled with antifreeze.

For environmental reasons, this is a 30% ethanol solution. Water is naturally filled with groundwater, and water flows from heat to heat from heat.

If the hole is not long enough, or if it tries to get super high power from the ground, that water and even freezing can be frozen, limiting the maximum heat output of these systems. This is the return antifreeze temperature and serves as one indicator of the automation circuit.

Approximately 1 meter works 50-60W of thermal power. Thus, to set the power of a heat pump with a capacity of 10 kW, a depth of about 170 m is required. It is impossible to drill deeper than 200 meters, less to make more wells at a depth of 0 to 10 meters from each other. Even for a relatively small house of 110-120 m2 with low energy consumption, the repayment period is 10-15 years.

Almost all existing units on the market operate during the summer, while heat (mainly solar energy) is taken from the rooms and dissipated into rock or groundwater. In the Scandinavian countries, stony granitic granite serves as a huge radiator that receives heat in the summer (day) and dissipates it in the winter (night).

In addition, heat is constantly supplied from the depths of the earth and from groundwater.

3. Extracting heat from the earth

The most efficient, but also the most expensive schemes involve collecting heat from the ground, where the temperature does not change throughout the year at a depth of several meters, allowing installation almost independent of time. As for semi-annual instruments in Sweden in 2006, 50,000 Finnish and Norwegian years were installed at an altitude of 70,000 g. When using as a grounding line of the circulation of the thermal energy of the Earth, frozen in the ground at 30-50 cm when the soil in this area is frozen.

In practice - by 0.7 - 1.2 meters. The minimum recommended distance between the collector pipes is 1.5 meters,

Drilling is optional, but a large area requires extensive ground work, and the pipeline is more prone to damage. The efficiency is the same as when selecting heat from the hole. No special soil preparation is required. However, it is desirable that the area be used with a wet shower, but if it is dry, the circuit should be longer. Approximate value of thermal power per 1 m of pipeline: in clay - 50-60 W, in sand - 30-40 W for moderate width, and less in the north.

Thus, to install a heat pump with a capacity of 10 kW, a length of 350-450 m is required, which requires a plot of land of about 400 m2 (20 x 20 m).

When properly calculated, the contour has little effect on green spaces.

Advantages and disadvantages of heat pumps

The advantages of heat pumps are, first of all, savings: to transfer 1 kWh of thermal energy to the heating system, only 0.2-0.35 kWh of electricity is required.

Since the conversion of thermal energy into electricity at large power plants occurs with an efficiency of up to 50%, the fuel efficiency when using heat pumps increases. Requirements for ventilation systems of premises are simplified and the level of fire safety is increased. All systems operate in closed circuits and do not require any operating costs, other than the cost of electricity required to operate the equipment.

Rice. fourth Scheme of using heat from a heat pump in a house

fifth Heat pump diagrams

Another advantage of heat pumps is the ability to switch from heating to winter in air conditioning in summer: simply instead of a radiator, an external manifold connects fan coil units or cold ceiling systems.

The heat pump is reliable and the operation is controlled by automation.

During operation, the system does not require special maintenance, manipulations do not require special skills and are described in the operating instructions.

An important feature of the system is a completely individual character for each consumer, which is the optimal choice of a stable source of low potential energy, calculation of the conversion factor, return, etc.

The heat pump is compact (its module does not exceed the size of a conventional refrigerator) and is almost silent.

By 2012 there are more than 3.5 million devices in Japan and about 500,000 homes in Sweden are heated by heat pumps.

The disadvantages of geothermal heat pumps used for heating are the high cost of installed equipment, the need for a complex and radical assembly of external underground or underwater heat exchangers.

The disadvantage of air source heat pumps is the lower heat conversion efficiency, which is associated with the low boiling point of the refrigerant in the external air evaporator. A common disadvantage of heat pumps is the relatively low temperature of the heated water, in most cases not more than +50 ° C ^ +60 ° C, the higher the temperature of the heated water, the lower the efficiency and reliability of the heat pump.

The use of alternative energy sources today seems to be a priority. The transformation of wind, water and solar energy can significantly reduce the level of environmental pollution and save the financial resources necessary for the implementation of technological methods for generating energy. In this regard, the use of so-called heat pumps looks very promising. A heat pump is a device capable of transferring heat energy from the environment into a room. The heat pump calculation method, necessary formulas and coefficients are presented below.

Sources of thermal energy

Energy sources for heat pumps can be sunlight, heat from air, water and soil. The process is based on a physical process, due to which some substances (refrigerants) are able to boil at low temperatures. Under such conditions, the performance coefficient of heat pumps can reach 3 or even 5 units. This means that by spending 100 W of electricity to operate the pump, you can get 0.3-0.5 kW.

Thus, the geothermal pump is able to completely heat the house, however, on the condition that the temperature of the outdoor environment is not lower than the temperature of the calculated level. How to calculate a heat pump?

Technique for calculating the power of a heat pump

For this purpose, you can use a special online heat pump calculator or perform calculations manually. Before determining the pump power required for heating the house manually, it is necessary to determine the heat balance of the house. Regardless of the size of the house for which the calculation is made (calculation of a heat pump per 300m2 or per 100m2), the same formula is used:

• R is the heat loss / power of the house (kcal / hour);
• V is the volume of the house (length*width*height), m3;
• T - the highest difference between the temperatures outside the house and inside during the cold season, C;
• k is the average thermal conductivity of the building: k=3(4) - a house made of planks; k=2(3) - single-layer brick house; k=1(2) - brick house in two layers; k=0.6(1) - thoroughly insulated building.

A typical calculation of a heat pump assumes that in order to convert the obtained values ​​​​from kcal / h to kW / h, it is necessary to divide it by 860.

Pump Power Calculation Example

Calculation of a heat pump for heating a house using a specific example. Suppose that it is necessary to heat a building with an area of ​​100 sq.m.

To get its volume (V), you need to multiply its height by its length and width:

• V=10x10x2.5=250 m3.

To find out T, you need to get the temperature difference. To do this, subtract the minimum outdoor temperatures from the minimum internal temperatures:

• T=20-(-30)=50°C.

Let us take the heat loss of the building equal to k = 1, then the heat loss of the house will be calculated as follows:

• R=1*250*50=12500 kcal.

The heat pump calculation program assumes that the heat consumption of the house must be converted into kW. We convert kcal / hour to kW:

• 12500 kcal / hour / 860 \u003d 14.53 kW.

Thus, for heating a house made of two-layer bricks with an area of ​​100 square meters, a heat pump of 14.5 kW is needed. If it is necessary to calculate the heat pump for 300m2, then the appropriate substitution is made in the formulas. This calculation takes into account the need for warm water needed for heating. To determine the right heat pump, you will need a heat pump calculation table showing the technical characteristics and performance of a particular model.

When we developed our heat pump, the concept was to build a reliable, durable unit first. At the same time, the heat pump must be understandable to the end customer during its operation, must operate in “non-ideal” modes (if such occur, for example, when the primary source of low-grade heat is incorrectly calculated or the probe breaks) and heat the house in winter before the onset of heat. The heat pump must have all the necessary protections so that errors during installation or subsequent operation cannot damage it. WThe protection in our heat pump is twelve. By current, thermal, overheating, hypothermia, temperature (2 pcs.), anti-cyclical, low pressure, high pressure, temperature protection of the motor winding, control of the supply network.Our Henk heat pump is easy to understand for installers and easy to use. We do not charge for "connection". Many of our customers install it on their own or by their plumbers in consultation with us. However, our warranty obligations remain unaffected.

Pricing for a Henk heat pump

As a manufacturer of heat pumps, it is quite easy for us to get maximum discounts on components and components from suppliers and manufacturers. It is not difficult to reduce the price of Henk heat pumps by 30-70 thousand rubles, depending on the model, due to cheaper components, while the profit that we lay down will not change. We fundamentally do not follow this path, conducting explanatory work. We also try to sell our products to reliable installers who honestly do their job, do not think only about momentary profit, saving on everything they can. Fortunately, the black list is very small. We adhere to a simple and honest rule - praise your own and do not scold someone else's. We do not compete with anyone. We have our own customer and our own way. In terms of price, Henk heat pumps are located between Chinese and European ones, but are made on exactly the same compressors and heat exchangers as European pumps. Note that the power of heat exchangers in our heat pumps is 20-30% higher than necessary, this compensates for the loss of thermal conductivity of non-freezing liquids, in comparison with water.

Assembly of heat pumps

We pay special attention to the assembly of our heat pumps. It takes one and a half to two years to “cultivate” an employee who understands the whole process. And the word QUALITY, for such an employee, is not an empty phrase. Heat pumps undergo evacuation, drying and pressure testing of the freon circuit, which is almost completely soldered, to reduce possible refrigerant leaks. The remaining four threaded connections are steel and are crimped with a special press.

Stainless heat exchangers are soldered with 40% silver solder. Thick-walled copper pipe of well-known brands. Insulation - foamed rubber (Germany). The hottest upper part of the compressor is also insulated. In power supply circuits, we also install the best components (ABV, Schneider, etc.). Low-voltage automation and electronic controllers, produced in the Republic of Belarus. The entire electrical part is re-stretched before final assembly. All electrical cables are protected by special corrugated and heat shrink tubes. The ends of the wires are sealed with lugs. Some important electrical connections are additionally soldered with solder. Only the alarm LEDs in the control box can be classified as inexpensive components, but during normal operation they should not light up. In case of any problems or fulfillment of additional wishes of the customer, any components are always in stock, there is no need to wait for a solution for a long time. This is important, especially during the heating season.

Heat pump - management and regulations

The operation of the heat pump control unit is designed so that the whole circuit algorithm is very simple. The display makes it easy to understand, even from a distance, what is happening with the heat pump. If a question arises, as a rule, it is resolved with a simple phone call.

You don't need a computer to program! It is very easy to lower or raise the temperature, change the hysteresis, calibrate the sensors.

The heat pump has an adjustable amount of refrigerant entering the evaporator. It allows you to very accurately adjust your heat pump exactly to your heat source (ground collector, wells or probes) and to your heating devices in the house, since each system is very individual and has its own “character”, which will allow you to achieve maximum efficiency of the entire system.

Important! Each model of our heat pump is recommended for a certain heated area, based on 80-100 watts of heat per square meter. This allows us to take into account our harsh Russian winters and some builders' blunders. However, strict foreign construction standards allow spending only about 30 watts of heat per 1 sq.m. Therefore, there is a misconception that, for example, our Henk-120 heat pump is able to heat only 120 sq.m, consuming 1.7 kW of electricity, and an imported pump heating 150 sq.m consumes only 1 kW!

By the way, in Russia, the customer, according to his mentality, wants to maintain comfortable +25 +26 degrees C in the whole house in any frost, while Europeans are ready to “endure” the coldest five-day period in a sweater.

Tuning and warranties

At the request of the customer, we can install frequency regulators. They are able to smoothly start and stop the compressor. Installation of the GSM module is possible. It is possible to assemble the heat pump on compressors with digital power control of the entire heat pump, built-in solenoid, from 10% to 100%. However, the cost of a "pedigreed" frequency converter is comparable to 1\2-3\4 of the cost of a compressor, and if you install a cheap one, the question arises about the reliability of the entire system.

In winter, in frost, a short period of time is enough to defrost the entire system. Some customers think about some kind of savings, about lowering the temperature in their absence (for example, if they come to the dacha only for the weekend). So, if we calculate that the compressor will have to work more on Thursday-Friday, after a “rest” on Monday-Tuesday, plus maintenance of the GSM card, it turns out that there is no difference at all. My personal opinion is that the GSM module is a very useful option! However, it can be put quite simple (for example, 4-zone), to control the presence of supply voltage throughout the house, control the overall temperature, penetrate into the home ... In any case, you will have to someone go and eliminate the cause. For serious tuning, there are very reliable proprietary control and management units. There are enough fans of smart and complex systems. But we should not forget that only three nodes heat the premises .... compressor and two heat exchangers.

When the warranty period of a heat pump ends, the question arises of how expensive and difficult repairs are? I can responsibly declare that to repair the entire heat pump control unitHenkalmost anyone can. The price of heat pump parts is negligible. We'll just show you how to do it.

Sincerely, Savostyanov Igor Yurievich

The heat output of an air-to-water heat pump (HP), otherwise, the amount of renewable heat extracted from the environment, is directly proportional to the outdoor temperature. The colder the air, the more expensive it is to extract heat from it. The COP conversion factor varies with ambient temperatures: the lower the outside temperature, the more energy the air source heat pump consumes.

Determining the power and choosing a heat pump is a rather complicated matter. Usually, real figures and performance diagrams are supplied by heat pump manufacturers, as well as special software for calculating and selecting equipment. Here you enter data for a specific object located in a specific temperature region.

Heat pump: heat output for heating and domestic hot water

Let us analyze on what factors the HP power and, accordingly, the cost of HP units, as well as the efficiency of its operation depend.

Radiators or underfloor heating

A heat pump heating system is usually implemented on the basis of a radiator distribution and/or a system with underfloor heating, wall heating or a fan coil system. At the same time, the heating medium heating temperature differs from 35-45 °C - for warm floors, up to 65-75 °C and higher - for the radiator system, which affects the power of the HP. The lower the temperature of the coolant in the heating system, the lower the energy consumption, the lower the heat output, the cheaper the equipment. For the modernization of heating systems with radiators when replacing expensive gas boilers, high-temperature air heat pumps with heating of the heat carrier up to 80 °C can be installed. For example, Hitachi YUTAKI S 80 heat pumps. Even if the coolant is heated to 65 degrees and above, such a system is several times more economical than a gas boiler.

Implementation scheme: HP only, HP + reserve boiler

TN. If only the heat pump is running, it must fully solve the problems of heat supply and water heating, connecting the built-in electric heater at peak times.

HP + boiler. If a gas or pellet boiler is previously installed, it can take over some of the peak loads and reduce the overall energy consumption of the heat pump.

There are various schemes of HP operation, selected individually for each object: monoenergetic (only on electricity), monovalent (HP + heating element) or bivalent (HP + boiler). The optimal temperature that is economically advantageous for switching to a backup heat source is called the “bivalence point”. For Kyiv and the region it is -7 °C.

Thermal insulation of the building

When choosing a heat pump for heating a house, you should know that a more insulated house will require several times less heat than a building without thermal modernization. The values ​​of heat losses (specific heat loads) for various types of buildings are given in the table.

From this it can be seen that in order to compensate for the heat loss of a room of 100 m2 in a well-insulated house, you will need:

Q H \u003d 50 W / m2 x 100 m2 \u003d 5000 W or 5 kW of thermal power.

Estimated heat loss values ​​are given based on the calculated minimum temperature, for example, for the Kyiv region it is -22 °C.

Accordingly, for a poorly insulated house we get:

Q H \u003d 200 W / m2 x 100 m2 \u003d 20,000 W or 20 kW of thermal power.

Such a difference: 5 kW and 20 kW makes it necessary to take steps to carry out thermal modernization (insulation) of the building, and then choose a more affordable and cost-effective heat pump.

Heat pumps for heating and water heating (DHW)

When choosing a heat pump for a private house, the operation of a heat pump for heating water for a kitchen, bathroom or shower is usually taken into account. At the same time, the daily distribution of loads is taken into account. They use hot water more often in the evening or in the morning, and in winter, the work of HP for heating also joins these loads. Usually, for heat pump systems, the tasks of hot water supply are more priority, and then heating, the calculation is based on the total heat loads: for heating and hot water.

To determine the thermal power of a HP for heating water for domestic needs, they use standard data on the consumption of water of a certain temperature and total heat consumption, based on the number of people living in the house.

For one person, let's take a rate of 50 liters of water with a temperature of 45 ° C, which corresponds to a consumption rate of 0.25 kW of thermal power.

We get that for a family of four people living in a private house of 100 m2, the heat output is needed:

Q W \u003d 0.25 kW / person * 4 people. = 1.0 kW

Now it is possible to carry out an average calculation of the thermal power, taking into account the total loads for heating the coolant for the heating system and heating water for domestic needs.

The total thermal power for heating and hot water for a well-insulated house:

Q SUM \u003d Q H + Q W \u003d 5 kW + 1 kW \u003d 6 kW.

The total thermal power for the heating system and hot water for a poorly insulated house:

Q SUM \u003d Q H + Q W \u003d 20 kW + 1 kW \u003d 21 kW.

And for the conditions of the “bivalence point”, when it is -7 ° C outside, and it is necessary to maintain +20 ° C inside the house of 100 m2, it will be required, taking into account the temperature difference:

Q cal.. = 6 * (20-(-7))/(20-(-22)) = 6 * 27 / 42 = 3.86 kW of heat from the heat pump.

And in the second example, for a building without thermal insulation, it is necessary:

Q cal.. = 21 * (20-(-7))/(20-(-22)) = 21 * 27 / 42 = 13.5 kW of heat from the heat pump.

Based on these data, taking into account the temperature of the “bivalence point” and with a power margin, a close larger value of the heat pump heat output is selected from the model range.

What is the power reserve?

• Inlet water temperature fluctuations. Everyone knows that tap water is much colder in winter and the temperature difference between the water entering / leaving the HP is greater in winter.
• The need to heat water to the desired temperature in the storage tank if it is not used from it for a long time.
• Increased consumption of hot water and its heating to a higher temperature in winter.

According to the tables offered by the manufacturer, based on the outlet water temperature and the outside air temperature, the set of the indoor unit and the corresponding outdoor unit of the heat pump is selected according to the power. An example is a technical data sheet for Hitachi Yutaki S series high-efficiency air-to-water heat pumps. For the calculated data, a model with a heating capacity of about 5.0 kW is suitable.

What determines the cost of a heat pump?

The more powerful the heat pump, the higher its price.
How to reduce the cost of a heat pump?

• Properly and professionally perform calculations and selection of equipment.
• Insulate the building.
• Minimize heat loss through windows and ventilation.
• Install low-temperature underfloor heating or fan coil units or a mixed system (radiators + underfloor heating, fan coil units + underfloor heating).
• Apply a bivalent HP + boiler scheme to reduce the load on the HP.
• Take part in the IQ energy program and save up to 35% of the cost of equipment and installation.

A more accurate selection of a heat pump, in order to avoid unnecessary costs or losses, is best left to professionals.

To choose the right heat pump, the prices for which and for installation services would be reasonable and justified, contact the competent experienced specialists of AKLIMA. We have extensive experience in the implementation of modern heat pump systems and offer high-quality services for the installation and maintenance of such equipment throughout Ukraine.