Air-to-water heat pump: application features. Types and principle of operation of heat pumps for heating a house. Which air/water heat pump is better?

Currently, alternative versions of units that can provide heating for a private home are beginning to become widespread.

You can install an air-to-water heat pump from manufacturers such as Mitsubishi, Nibe or Gree yourself. Despite the frankly high cost of such units, air-to-water systems of the Mitsubishi, Nibe or Gree brands have, for the most part, positive reviews.

This is due to the fact that the characteristics of devices such as an air-to-water heat pump from companies such as Mitsubishi, Nibe or Gree can significantly reduce heating costs.

1 What is the design of air-to-water heat pumps?

It should be noted that the degree of efficiency of DIY air-to-water systems using pool water is slightly lower than that of air-to-water devices from the Mitsubishi, Nibe or Gree brands.

This is due to the fact that the operating principle of an air-to-water heat pump, which works using water from the pool and is assembled with your own hands, depends on the time of year.

Such a pump does not work very efficiently when adjusted for low temperature conditions in the cold season. Based on this, the power of a self-made air-to-water heat pump that takes water from the pool in winter at low temperatures is significantly reduced.

However, to install an air-to-water heat pump from the Mitsubishi, Nibe or Gree brands yourself, you do not need to calculate the exact depth of the well and perform precise calculations.

Also, when installing a Mitsubishi, Nibe and Gree pump, there is no need to calculate the amount of excavation work that may be done around the pool.

In order to install a Mitsubishi, Nibe or Gree air-water system pump with your own hands and calculate its efficiency, it is enough to select the necessary equipment and choose a suitable location, for example, on the roof or near the pool.

Thus, it is quite possible to install a Mitsubishi, Nibe or Gree air heat pump with your own hands near the pool, without having to carry out a large number of all kinds of large-scale preparation work.

Another significant advantage of a Mitsubishi, Nibe or Gree heat pump is the operating principle in which the resulting heat can be reused to operate the system.

In this case, the low temperature regime will not be a significant hindrance. This is evidenced by numerous user reviews.

The operating principle of a heat pump allows you to use the heat that leaves the room, along with exhaust air or water from the pool.

However, in order to compensate to some extent for the lack of power in those located near the pool, it is necessary to provide for various options for the use of alternative heating systems.

The principle of operation of a heat pump located near a pool is based on the fact that almost any environment contains a certain amount of thermal energy when its temperature is above +1 degrees Celsius.

An air source heat pump is based on the principle of transferring heat from a source with a low thermal energy potential to a heat recipient with a higher temperature.

In practice, an air heat pump works due to the fact that the coolant enters the pipeline, which is buried in the ground. As a result, the coolant is heated.

The air heat pump is designed in such a way that the coolant circulating in it, after entering the evaporator or heat exchanger, transfers all the accumulated heat energy to the internal circuit.

An air source heat pump is equipped with a refrigerant that circulates through the external circuit and, when heated in the evaporator, is transformed into a gaseous or vaporous state.

In the presented heat-type pumps, gaseous refrigerant enters the cavity of the compressor, where it is compressed due to intense exposure to high pressure.

As a result, there is an increase in the temperature of the refrigerant circulating inside. After completing the cycle, the refrigerant loses heat and returns to the system in its original state.

The use of a powerful fan allows you to take air from the external environment, which, upon contact with the evaporator, continues its circulation through the coil.

Next, the cycle is closed, and the refrigerant, when heated, again enters the compressor. The technical characteristics of the presented device can be found using the example of the Gree GRS-CQ air-to-water pump model:

Power consumption: 200 W;
Maximum water pressure: 3 bar;
Water consumption limit: 7.5 l;
Connecting diameter (refrigerant, water): 12-17 mm;
Incoming water temperature: from +7 to +25 °C.

The presented units are divided into two subtypes based on the features of the layout diagram. They are presented in the form of a split system and in the form of a monoblock.

The monoblock looks like a single device, all components of which are collected in one housing. It can be installed either in the middle of the house or outside.

When carrying out an internal type installation, it is necessary to take care of the installation of a passage channel that serves for air intake.

Outdoor installation is most preferable; thanks to it, the compressor, as a source of noise, can be located outside the room.

The split system is made by dividing the unit into two different blocks. The first includes a capacitor and a system attached to it that provides automatic control. The second outdoor unit is equipped with a compressor.

2 Device reviews

The overwhelming majority of existing reviews about the operation of the units and their efficiency are positive.

Sergey, 37 years old, Irkutsk:

I live with my family in a large country house. We don’t have a gas main, so I decided to save on electricity costs and installed a split system in the form of a Mitsubishi heat pump. Now, during the cold season, all rooms are warm. The equipment is working properly. I advise everyone.

Pavel, 45 years old, Voronezh:

I have been disappointed with conventional heating systems for a long time, and have been looking for a suitable alternative for some time. I opted for a monoblock air-water system from Nibe. The installation was carried out by a specialist. With the first autumn cold, I started it up and was surprised at how quickly all the rooms in the house warmed up. I now recommend her to everyone I know.

Anton, 50 years old, Vologda:

I sell heating systems. I recently started selling air/water systems. All customers are satisfied, I only heard positive feedback from them.

2.1 How to make a system with your own hands and connect it in series?

If desired, almost all the elements that make up a heat pump system can be made yourself. To do this you will need:

Metal tank made of stainless steel with a volume of 100 l;
Plastic barrel with a wide neck;
Pipes made of copper;
Set of couplings and adapters;
Ventilator DU-15;
Safety valve;
Pressure gauge;
Devices for implementing automatic control;
Brackets to ensure fastening of elements.

It should be remembered that for full operation of the compressor you will need a fairly large current. Based on this, the recommended load level on the electric meter should be approximately 40 amperes.

In order to produce a thermal unit with a power of 9 kW, you need to acquire a compressor with a power of 7.2 kW. In addition, it is necessary to make a coil from a copper tube.

To do this, you need to carefully wrap the pipe around a cylinder with the required diameter. In order to make a capacitor, you need to cut a steel tank into two equal parts, and then place a copper coil inside it.

Then you need to cut the barrel made using plastic into two parts from which the evaporator will be made. Next, all elements are connected in the following order:

A coil made of copper pipe with a ¾-inch diameter is inserted into the evaporator.
Using tubes, the evaporator is connected to the heating system in the house.
Check the quality of the assembly and add refrigerant into the system.
Perform a test run.

In general, the use of heat pumps to provide heating at home is very convenient and profitable. Such a unit can produce heating of a living area of more than 400 square meters. meters.

Installation of the unit in most cases pays off within the next few years of its operation. If you own a house with a small living space, then the installation of the structure can be done by yourself, and all its components can also be made independently.

It is worth remembering that the compressor must be mounted indoors and preferably on the wall using reliable and strong metal brackets.

When connecting the pressure tank, it is recommended to use threaded connections due to their high mechanical strength. It is worth noting that all manipulations associated with the stages of final installation of equipment (soldering, injection of freon into the system pipeline) must be carried out with the participation of a qualified specialist.

Insufficiently skillful actions can lead to irreversible mechanical damage to parts and elements of equipment, and are associated with a high likelihood of domestic injuries.

Before performing a test run of pumping equipment, it is necessary to undergo a detailed diagnosis of the general condition of all home wiring and the electric meter.

All outdated and dilapidated elements must be replaced with new ones. In some cases, the installed one does not meet the expectations of the home owners.

Most of this is due to incorrect thermodynamic calculations. The result of this is a system that does not have sufficient power and unreasonably high costs for overpowered equipment.

2.2 How does an air-to-water heat pump work? (video)

Heat pumps run on free and renewable power sources. Know-how extracts latent heat from water, soil and even air. This type of hot water supply and space heating is relatively new. And therefore, the engineering system requires careful selection and informed decisions.

Design and principle of operation of a heat pump

Scientists are looking for alternative energy sources. There are several reasons for this. The main ones are: limited earth resources, cost savings and environmental friendliness of systems.

A heat pump is one example of using energy from the environment. It comes from soil, air or water. Therefore, devices are divided into the following types: “brine - water”, “air - water” and “water - water”. Heat can also be released directly into the air through ventilation.

The idea of heat pumps was born in 1982 in the UK. Three years later, Peter Ritter von Rittinger refined it and implemented the world's first such system. He is the official inventor of the heat pump.

Next came Robert Weber, who began to extract energy from the soil. And it was an accident that prompted him to do this. Touching the hot pipe, he realized that the heat was escaping randomly. And it can be reused.

Through experimentation, he began to circulate water through a spiral pipe, simultaneously heating air and water. This is how the operating principle of a heat pump was developed.

Today it is used to heat the following objects:

private houses,
children's water parks,
educational establishments,
office centers,
swimming pools,
shopping complexes.

For the heat pump, a pipeline is laid under the surface of the soil. The thermal fluid passes through its structure and heats up by several degrees. In the evaporator, the collected heat is transferred to the pump. In this case, the refrigerant boils at high pressure and a temperature of -50 ° C. Vapors are generated in the compressor. Low-potential energy under pressure turns into high-potential energy. Next, heat exchange occurs in the condenser between the hot gas and the coolant. The heated water enters the water supply system, and the cooled refrigerant continues to circulate in the structure.

Heat pumps have the following characteristics:

price,
heated area of the room,
power,
dimensions occupied by equipment,
energy source,
electricity consumption,
lifetime.

The system is installed both during the construction of a new house and when insulating an old one.

Advantages and disadvantages of the system

A heat pump for heating has a number of advantages compared to gas and solid fuel boilers:

Fire safety,
free hidden energy from the environment,
simplified requirements for room ventilation,
possibility of air conditioning in hot weather,
autonomy,
ease of operation,
without chimney,
relative compactness of the equipment,
noiselessness,
not explosive
no fuel smell,
operation 16 - 20 years before major overhaul.

On the other hand, the system has its drawbacks:

heating water to a maximum value of 50 - 60 °C,
large state duty on the import of equipment,
long-term payback of the system in 5 - 10 years,
the need for a one-time large deposit of funds,
difficulty in installing underground locations,
little practical use in the country,
decrease in pump efficiency with higher water heating.

Device types

Compression pumps operate from the electrical network, while absorption pumps operate from fuel.

Depending on the type of energy source, heating devices are divided into geothermal heat pumps, air-based heat pumps and systems using recycled materials.

Geothermal systems use heat from underground/surface water or soil. They come in closed or open types.

Closed systems are divided into:

horizontal pumps with a collecting device located below the soil freezing level,
vertical with immersion of the collector into wells to a depth of 100 - 200 m,
water pumps with absorbing rings in reservoirs.

Open pumps return water after it passes through the pipeline. In practice, this is possible with a large reserve and upon obtaining permission from the environmental authority.

Air heat pumps extract latent heat from air masses at temperatures down to -20°C.

It is advisable to use heat from pipelines, that is, secondary heat, at large industrial enterprises.

Pumps can generate 100% of the heat in the premises, or serve as an additional source of heating. Such exploitation is called monovalent and bivalent, respectively.

A number of modern air conditioners perform the function of air-to-air heating. But their temperature range is limited. If a heat pump provides year-round heat, then the autonomous analogue does not work at negative temperatures.

Calculation and selection of heat pumps for the home

When installing a pump heating system, it is better to give preference to heated floors rather than radiators. Because the smaller the temperature difference between the heat source and its required level, the more efficient the heating.

It is important to understand whether the site allows for work on laying the collector. A horizontal network requires a large area. At the same time, structures cannot be erected over it, since the soil will not receive the necessary solar energy.

If the house has a good ventilation system, then an air heating system can be integrated into it.

The power of the heat pump is selected depending on the mode of its use. Let us remember that there is monovalent and bivalent use of equipment. In our country, the cold season occupies a small part of the time, namely 35 - 40 days with temperatures below -10°C. Therefore, it is more advisable to connect traditional heating during this period. And for the rest - dual-rate heat pumps for the home to reduce the price of the system. This will save money on earthworks for installing a complex heating network. In this case, the optimal power distribution will be a ratio of 60:40. Where a big burden goes on technology know-how.

During periodic power outages, it is worth increasing the pump strength by a correction factor. Which is equal to 0.3 for every hour without electricity per day.

It is clear that the higher the temperature of the energy source, the more efficient the alternative heating system will work. There are several power source options for it.

In warm regions, air-to-air and air-to-water heat pumps will be productive. In mid-latitude regions, it is advisable to use such equipment as bivalent equipment together with a conventional source of heating and water heating.

It is better to design a water-to-water heat pump with water intake from wells rather than from open reservoirs. Because the latter freeze to the bottom in winter.

But there is not always underground water or a reservoir near the house. A universal option is a system that extracts heat from the ground. Because he is everywhere. At the same time, at a depth of 2.5 - 3 m, its temperature averages +10 °C per year. Which does not change significantly during the cold season.

Horizontal heat collectors are cheaper. But they have a number of disadvantages compared to their vertical counterparts:

the temperature at depth is greater than under the top layer of soil,
Only small green spaces can grow on the surface.

On a site with vertical heat exchangers, trees can be planted and structures can be erected.

You can assemble the pumping unit yourself, but it is better to contact specialists. Because its design is complex and expensive. And there are no high-quality instructions for sequential collection.

With a well-thought-out control system, it is possible to maintain different temperatures in different rooms of the house.

Heat pumps have positive reviews abroad. Unfortunately, in our country, an alternative power source remains an expensive pleasure without widespread practical application. Therefore, it is more advisable to give preference to international pump manufacturers. Their technologies are proven in practice.

When installing heat pumps, it is necessary to take care of additional insulation of the room. The scope of work includes replacing double-glazed windows and covering walls with heat-insulating material.

Cost of heat pumps

The capital investment for a heating system depends on its type, equipment manufacturer, drilling volume and electricity tariffs.

The price for geothermal heat pumps when installing a probe will be:

device - 7500 USD,
installation of the system - 7500 USD,
operating costs - 500 USD in year.

Systems with horizontal collector:

pump - 7500 USD,
installation - 3700 USD,
monthly expenses - 560 USD

Water-to-water heat pump:

equipment - 7500 USD,
installation work - 5000 USD,
cost of electricity - 450 USD

An air heating system is the most inexpensive analogue. Since no excavation work is required. However, operating costs are higher:

pump - 10,000 USD,
installation - 620 USD,
maintenance - 750 USD

Buying a heat pump means purchasing:

the equipment itself,
buffer capacity,
boiler for heating water.
communication system between all elements,
control and monitoring panel.

And land work involves the following stages:

clearing the area of vegetation and solid elements such as stones,
drilling the required number of wells or trenches,
laying and arrangement of collectors,
construction of test wells,
connecting the pipeline to the heating, water supply or ventilation system,
reclamation of the territory,
system tincture.

Heat pump manufacturers

A homemade heat pump is great, but not reliable. Therefore, it is better to pay attention to famous manufacturers. Which test their technologies, and their specialists will come to the rescue in time during installation, repair and maintenance of equipment.

NIBE Industrier is a well-known international company for the production of heating systems. Its developments use alternative and environmentally friendly power sources. NIBE products are certified in Europe and America. This means it meets the parameters of reliability and efficiency.

Viessmann has a 100-year history of developing refrigeration, heating and climate control systems. Heat transfer equipment has been manufactured and modernized for 30 years. From the very moment the principle of using ecological heat was born. The pumps are sold in 70 countries around the world with production in 10 of them.

Heating equipment is sold by the international German company Vaillant. But renewable energy equipment is only one of its activities. The manufacturer's exports cover 60 countries.

The Ukrainian company FLY-TEK LLC offers systems assembled from foreign components. The cost of its heat pumps is 30% lower than international analogues.

The Sintek company has been operating on the Ukrainian market for 10 years. It produces heating equipment under the SintSolar brand. In 2000 she was awarded for the development of effective technologies.

The Krasnodar company Atmosystems launched the production of heat pumps in 2005. Afterwards, she became a distributor of the international manufacturer Heliotherm. The latter is the only heat pump manufacturer to be nominated for a State Award in Australia for environmental and energy conservation technology.

Heat pump care

Maintenance involves an annual professional inspection of all system elements.

The pump must be turned on a few hours after installation to allow the system to preheat.

Heating system flushing, emergency repairs and maintenance are usually guaranteed by the manufacturer. Therefore, keep documents confirming the purchase and installation of equipment.

Sometimes it is advisable to use the service of remote monitoring of the quality of heat pumps. This will allow you to quickly respond to deviations in the system. It is provided by the system vendor.

Theoretically, air can be used as a source of low-temperature thermal energy, regardless of its temperature. On practice air-to-water heat pumps effective at air temperatures not lower than -15 C. Today there are already pumps on sale that operate at temperatures of -25 C, but their cost is still too high, which makes this type of heating equipment inaccessible to the general consumer.

In its most primitive form, an air-to-water heat pump can be thought of as an air conditioner used to cool the environment and discharge “excess” heat into a heated room.

In this case, the air-to-water heat pump does not require digging pits or drilling wells, laying pipelines along the bottom of reservoirs or installing vertical collectors necessary to enable water-to-water or ground-to-water heat pumps. It is easy to use and at the same time allows you to obtain inexpensive heat for heating your home.

Monoblock or split system

Just like air conditioning systems, heat pumps of this type can be made according to 2 layout schemes:

In the form of a split system consisting of 2 blocks connected by communications
In the form of a monoblock

As a rule, a monoblock is a single device assembled in one housing and installed inside or outside the house. For indoor installation, it is necessary to provide a free channel for air intake. In this case, outdoor installation is preferable: it allows you to move the compressor, as a source of noise, outside the room.

Today, many manufacturers produce air-to-water heat pumps in the form of monoblocks. It is convenient and practical, it allows move freely pump and install it without complicated installation and connection. The only drawback is the low power of pumps of this type: from 3 to 16 kW.

The split system is divided into two blocks, one of which includes a condenser and an automatic control system. It is installed indoors. The second (outdoor) unit includes a compressor. Its Economic feasibility of installing air-to-water heat pumps

Air/water heat pumps are efficient at positive outside temperatures. They are widely used in the southern regions of our country: in the Kuban, Stavropol Territory, etc. where severe frosts are rare, and in winter the temperature rarely drops below zero.

This does not mean at all that in other areas of our country, with more severe climatic conditions, heat pumps of this type cannot be used. Not at all. It’s just that the efficiency of the air-to-water pump decreases as the air temperature decreases, along with an increase in the cost of electricity required to ensure the operation of the pump.

Therefore, the expediency operating a heat pump at negative air temperatures, as well as the selection of equipment in accordance with the required power, must be carried out by qualified heating engineers.

Today, the best option is to use an air-to-water heat pump for heating and hot water supply at above-zero ambient temperatures and to turn on a boiler or other source of thermal energy when frost sets in.

Video review of heat pumps

Another condition for using a heat pump to heat a house is the high thermal efficiency of the building and the absence of heat losses associated with poor-quality thermal insulation and drafts.

The main elements of geothermal heating systems are heat pumps, the main components of which are an evaporator, a condenser, a compressor, a thermostat and a refrigerant circulating through a closed system.

The correct combination of the presented elements into a single system makes it possible to release low-potential heat from the environment (soil, air or water), with its subsequent transformation into high-potential heat, necessary for the operation of heating systems and the provision of hot water.

The operating principle of any heat pump is closely similar to a working refrigerator, with the only difference being that in the refrigerator heat is removed and then displaced onto the radiator, while a heat pump takes heat from the environment and transfers it to the heating system.

This happens as follows:

The refrigerant is supplied to the evaporator, here evaporation is achieved by sharply reducing the pressure
During evaporation, the heat of the evaporator walls coming from the environment passes to the refrigerant, then the refrigerant, turning into gas, enters the compressor
The refrigerant, which is in a gaseous state, is subjected to high pressure after entering the compressor. As a result, the refrigerant is heated to 120-125°C and further moved to the condenser, where heat is transferred to the coolant. After “releasing” the heat, the refrigerant returns to the liquid state, and the cycle repeats until the set temperature is reached
The operation of the heat pump is controlled by a thermostat that opens and closes the circuit responsible for starting or stopping the compressor

How Geothermal Heating Works

The essence of geothermal heating is that low-grade heat is taken from the environment, converted into high-grade heat and then supplied to the house.

To ensure the operation of a heat pump, electricity is required, although its costs are 3-4 times lower than the thermal energy received. The efficiency of the heat pump is maximum and surpasses any heating boilers. The effectiveness of its use is also obvious, manifested in significant savings in money.

However, it is necessary to take into account that the cost of installing a geothermal heating system is very high, and payback occurs no earlier than after 15-20 years of operation.

Heat pumps can be classified into several types, the main of which is the type of source that “gives off” low-grade heat. According to this criterion, heat pumps can be divided into:

Ground;
Air;
Water;
Combined.

The most efficient and stable are heat pumps whose circuit is located in the ground. However, this significantly increases the cost of carrying out work, the implementation of which is impossible without the use of special equipment.

Air-to-air

The essence of the operation of heat pumps operating from an air source is similar to the operation of geothermal pumps. The only difference is that the heat source is not the soil, but the air. Such pumps can be divided into two types of systems - air-water and air-air.

The type of system is determined by the medium used to distribute heat in the building - water or air. The main advantage of “air” heat pumps, in comparison with geothermal ones, is their much lower cost.

This is due to the absence of the need for complex installation work to install an underground circuit.
A heat pump that operates on an air-to-air system is designed only to heat indoor air. Heat is extracted from the air outside by means of an evaporator unit mounted on the wall of the building.

Next, the heat is transferred to a condenser, which is placed indoors. Here the heat is transferred to the internal air, which, after heating, is returned back to the room. If it is necessary to heat large areas, various air flow distribution systems are used.

Air-to-air heat pumps are for heating purposes only. The advantages include high performance and heat transfer levels.

The main disadvantage is significant fluctuations in performance depending on the temperature of the external air masses. In this regard, geothermal heat pumps are much more stable, since the ground temperature at the location where the circuit is installed is practically constant.

Despite their variable performance, air-to-air heat pumps are very popular due to their environmental and performance characteristics.

Water-water

The design of water-to-water heat pumps is closely similar to geothermal pumps. The only difference is that the source is not soil, but water (natural and artificial reservoirs, groundwater and waste water).

The high average annual efficiency is explained by the high coolant temperature in winter. By arranging the heat exchanger in the form of a spiral, the installation area can be significantly reduced. Like any heating equipment, water-to-water heat pumps have their own advantages and disadvantages.

Negative sides:

High cost of a heat pump;
Impossibility of effective use at a significant distance from the heat source;
Specific requirements for the capabilities of the supply source.

The listed disadvantages are completely covered by the following advantages:

Minimum area for installation of the circuit;
There is no need to use special equipment;
High level of efficiency;
Possibility of organizing not only heating, but also hot water supply and passive cooling;
Uninterrupted operation;
Long service life;
Easy maintenance;
Minimum electricity consumption in terms of performance.

Air-water

According to the principle of operation, an air-to-water heat pump is similar to the operation of a household air conditioner, with the only difference being that as a result of their operation, it is not the air that is cooled, but the coolant (most often it is water).

Air-to-water heat pumps, unlike air-to-air system pumps, are capable of organizing not only heating, but also hot water supply.

Their only drawback is that high performance is only possible when the temperature does not drop below -15°C. Therefore, stable operation of air-to-air, air-to-water heat pumps and their high performance are achievable only in appropriate climatic conditions.

Having learned to pump gas from the bowels of the earth and burn it, humanity has received two serious problems. Global warming and environmental poisoning are too high a price for comfort. In addition, raw fuel is a limited resource, the reserves of which are quickly depleted. These factors have generated active interest in heat pumps - installations that extract clean energy from the ground, water and air. Without voracious boilers and harmful emissions, they provide homes with heat and hot water.

In the West, a heat pump for heating a home has become as common as an air conditioner or a washing machine. In our country, this unit is not yet familiar to most owners of private estates and dachas. This article will help you get acquainted with the principle of its operation, existing varieties, advantages and disadvantages.

How does a heat pump work?

The simplest example that clearly explains the principle of operation of heat pumps is a household refrigerator. We all know that food is cooled in its freezer due to the circulation of refrigerant. Taking internal heat, the refrigerator throws it out. Therefore, the freezer compartment is cold, and the rear grill of the device is always hot.

The principle of operation of a heat pump is the opposite. Taking heat from the environment, it transfers it into the house. Figuratively speaking, the “freezer compartment” of this device is located outside, and the hot grate is in the house.

Depending on the type of external heat source and the environment that collects energy, heat pumps are divided into four types:

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

Installations of the first type extract heat from the ground using tubular collectors or probes. A non-freezing liquid circulates in the external circuit of such a pump, transferring heat to the evaporation tank. Here, thermal energy is transferred to freon, which moves in a closed loop between the compressor and the throttle valve. The heated refrigerant enters the condenser tank, where it transfers the resulting heat to water sent to the heating system. The heat exchange cycle is repeated as long as the installation is connected to the mains.

Heat pump operation diagram

The operating principle of a water heat pump is no different from a ground heat pump. The only difference is that it is powered by water, not soil.

An air source heat pump does not require a large external collector to collect heat. It simply pumps street air through itself, extracting precious calories from it. Secondary heat exchange in this case occurs through water (warm floors) or through air (air heating system).

Assessing the economic side of the issue, it should be noted that the greatest financial investment is required for the “ground-water” installation. To install its heat-receiving probes, it is necessary to drill deep wells or remove soil over a large area to lay the collector.

A ground source heat pump cannot operate without an external pipe system or deep wells with heat receiving probes

In second place is a water heat pump, delivered to the customer on a turnkey basis. It does not require digging or drilling wells to operate. It is enough to immerse a sufficient number of flexible pipes into the reservoir through which the coolant will circulate.

The cheapest units are air-to-air and air-to-water units, since they do not require the installation of external heat energy receivers.

A feature of the installation of most heat pump systems is that they are connected not to heating radiators, but to a heated floor. This is explained by the fact that the maximum water heating is up to a temperature of +45C, which is optimal for heated floors, but insufficient for normal operation of the radiator.

A beneficial feature of this installation for the owner is the possibility of reverse mode - switching over to cooling the premises during the hot period of the year. In this case, excess heat is absorbed by the underfloor heating pipeline and removed by a pump into the ground, water or air.

A simplified block diagram of a ground heat pump installation looks like this:

In addition to the heat pump, ground circuit and heated floor, here we see two circulation pumps, shut-off valves for hot water and heating, as well as a tank accumulating hot water for domestic use.

Characteristics of heat pumps

The main indicator by which the efficiency of a heat pump is assessed is the heat conversion coefficient, abbreviated as CPT (in the English abbreviation COP). It has nothing to do with the efficiency that is familiar to us - the efficiency factor. KPT (COP) shows how many kilowatts of energy the pump pumps per kilowatt of electricity it receives. Depending on the operating conditions, the CFC of a heat pump can range from 3 to 5, which, without further discussion, confirms the economic benefits of its use.

The most stable performance indicators are demonstrated by soil and water installations, since the temperature of water and soil does not fall below zero degrees. Units that collect heat from the air depend on its temperature. When the thermometer reaches sub-zero levels, their productivity decreases by an average of 40-50%.

The second operating parameter is power in kilowatts. It is selected based on the amount of heat loss of the building.

Calculation of heating a house with a heat pump

For normal operation of the heat transfer installation, high-quality thermal insulation of the building is necessary. Therefore, before purchasing a heat pump, it is necessary to insulate the walls, floors and ceilings, and then perform a calculation of heat losses (Q).

A simplified formula for calculating the amount of heat (W) leaving the house through the building envelope (walls, windows, floor, ceiling) looks like this:

Q = S x (difference between indoor and outdoor air temperatures)/ Rt.

S – area of the enclosing structure in m2;

Rt – thermal resistance of the material of the enclosing structure (taken from the SNiP tables on building heating engineering).

By alternately calculating the heat loss of walls, windows, floors and ceilings, they are summed up and the number of kilowatts lost by the house in 1 hour during the coldest period of the year is obtained. The heat pump power must be no less than the total heat loss. If, in addition to heating, the installation will heat water for domestic needs, then its power will be increased by 20%.

When choosing an air-to-air or air-to-water heat pump, you should focus on the thermal power that it develops in the low temperature region, since it is significantly lower than the power when operating in the warm season.

As an example, we give the parameters of the NIBE FIGHER F2300-14 air-water installation. Operating in a temperature range from +7 to + 45C, it produces about 18 kW, and at an air temperature of -15C only 10.7 kW.

Famous brands and approximate prices

The market for heat pump equipment in Russia has been formed. The leading positions here are occupied by foreign companies, such as: Nibe (Sweden), Mitsubishi Electric (Japan), Danfoss (Denmark), Vaillant (Germany), Viessmann (Germany), Mammoth (USA) and others. In terms of price-quality ratio, Russian-made products (Henk and SunDue trademarks) are not inferior to famous brands.

The estimated price (for 2016) of an imported ground-water heat pump with a power of 10 kW, designed to heat a house with an area of 100 m2 (without installation) is 500,000 rubles. For work on drilling wells, installing pipes and commissioning, you will have to pay an average of 80,000 rubles, not including additional materials.

Domestic equipment is cheaper. The price of a Russian heat pump with similar parameters is about 360,000 rubles. Its purchase with turnkey installation will cost about 430,000 rubles. The estimated price of a 10 kilowatt air-to-water heat pump is from RUB 270,000. The average cost of this unit with turnkey installation is 320,000 rubles.