A modern air-to-water heat pump is an extremely useful device. Even if the outside temperature approaches zero, it can successfully heat fairly large rooms. If ground-to-water or water-to-water heat pumps are easier to install in a private house with a spacious plot, then the air-to-water model is installed without problems in urban buildings, both residential and office.
How does this system work?
The world around us is full of energy, you just need to collect it and use it correctly. This is what air-to-water heat pumps are designed for. With their help, you can collect low-grade energy from the environment and convert it into high-grade heat that can heat your home very efficiently. Experts call this process the inverse Carnot principle, on the basis of which refrigeration units operate.
With the help of a powerful fan, ordinary air is taken in from outside. It is in contact with the evaporator, inside which is the refrigerant circulating through the coil. When heated, the refrigerant evaporates and enters the compressor. Here it is compressed and heated to a temperature of about 75 degrees and enters the condenser under pressure. There, the refrigerant condenses and turns into a liquid state, giving off heat to the house heating system. The liquid refrigerant enters the evaporator, where it is heated by the outside air, etc. The heating-evaporation-compression-condensation cycle repeats over and over again.
Outdoor unit heat pump air-water is placed on the site, choosing for this a place with good air circulation near the house
Advantages and disadvantages of such heating
A modern air-to-water heat pump is efficient and allows significant savings in heating costs, because:
- air can be called the most accessible and cheapest renewable resource;
- the cost of installing such a unit will be cheaper than installing other types of heat pump (ground-to-water, water-to-water, etc.), and the whole process is simpler and faster;
- heating can be carried out even at negative outdoor temperatures;
- the device works almost silently;
- effective air exchange inside the room is ensured;
- the installation can be controlled automatically.
Indeed, when building an air source heat pump, there is no need to drill wells or carry out large-scale excavation, no need to build a heat exchanger for the external circuit, etc. You will need two small channels through which air will be taken in and then returned to the outside. For this, two small pipelines are laid in the ground. There are also models that do not need such pipelines.
For an air-to-water heat pump, you will need a large fan that will supply air to the evaporator. The fan blades must be covered with a grate
There are few drawbacks to this design, but they should be taken into account. Although it is believed that an air source heat pump can work effectively all year round, it is better to use it in an area with mild and warm winter. It is not recommended to turn on such a heat pump at temperatures below -7 degrees. At the same time, the efficiency of the system in winter time will be lower than in spring or autumn. Although manufacturers claim that industrial models of this type of heat pumps can work quite successfully even at -25 Celsius. In an area with a harsh climate, a combination of a heat pump and a traditional heating boiler, which turns on only when it gets very cold, may be the most profitable option.
Of course, any heat pump requires electricity to operate. For every kilowatt of electricity consumed, the device allows you to get 3-4 kW of natural energy. Therefore, in the end, the use of a heat pump for heating is economically advantageous compared to the costs of heating with gas, diesel, solid fuel or heating with an electric boiler. However, you should not forget about the dependence of the system on the availability of electricity.
Algorithm for assembling a homemade unit
Almost all elements of an air source heat pump can be made independently. The compressor is recommended to be removed from a conventional split system. As a rule, such a device has suitable characteristics and operates quite silently. In addition to the compressor, you will need a number of materials:
- stainless steel metal tank, 100 liters or more;
- plastic barrel with a wide mouth;
- copper pipes of various diameters (pipe wall thickness - at least 1 mm);
- a set of couplings and adapters;
- electrodes;
- drain tap;
- air blower DU-15;
- safety valve;
- manometers;
- devices for automatic control;
- brackets for fixing system elements;
- freon etc.
Note! When the compressor is turned on, a sufficiently large current will be required, so the recommended design load of the electric meter in the house should be at least 40A.
To make an air source heat pump, you need:
- Stock up on a suitable compressor and brackets for mounting it on the wall. To make a 9kW heat pump, you need a 7.2kW compressor.
- Make a coil from a copper tube by winding the pipe evenly around a cylinder of the desired diameter.
- To make a condenser, cut a 100-liter steel tank in half, insert a copper coil inside.
- Fill tank and install threaded connections. To install the finished capacitor, you will also need brackets.
- Cut a plastic barrel to make a vaporizer.
- Insert a ¾ inch copper coil from the pipe into the evaporator.
- Another set of L-brackets is required to mount the evaporator on the wall.
- Connect elements in common system.
- Invite a refrigeration technician who will check the build quality and pump refrigerant into the system.
After that, it is necessary to ensure the intake of outside air and its discharge for contact with the evaporator, and also connect the device to the heating system of the house.
To make a coil from a copper tube for an air-to-water heat pump, you can take a cylinder of a suitable diameter from freon or gas and carefully wind the tube around it
The compressor for the air-to-water heat pump can be removed from the split system, making sure that it has enough power. A metal tank is suitable for the manufacture of a capacitor
The basic principles of operation of an air source heat pump are presented in the video using an industrial model as an example:
Please note that if it is decided to use a heat pump in parallel with a heating boiler, it is recommended to use when connecting.
A few words about power calculations
Before starting work on creating a pump, you should decide on its power. You should not make the unit "with a margin", as this will entail completely unnecessary material costs. The lack of power will affect the efficiency of the system, in this case, the house will be too cold.
Specialists for detailed calculations of the power of a heat pump use special programs that allow you to determine other parameters, for example, the area of a copper coil, etc. Craftsmen do it easier - they use online calculators that are installed on some specialized sites. In the special fields you should enter data about:
- the region in which the premises are located;
- the total area of a private house;
- ceiling height in rooms;
- degree of building insulation.
Based on these data, the program will give the calculated power of the heat pump. Of course, the better the building is insulated, the less heat will be needed to heat it, so it is recommended to solve the problem of thermal insulation even before installation begins. For you, we provide indicative data for general information.
Approximate dependence of the required heat output of a HP on the area of a house with good thermal insulation properties
Proper Maintenance Technology
The operation of the heat pumps is automatically regulated, so this system does not require any special daily care. Nevertheless, it is recommended to periodically, at least once a year, inspect all elements of the system in order to identify possible problems and prevent them. The owner of the heat pump should:
- Check the condition of all existing filters and clean them.
- Control the temperature of the oil in the compressor (it should be warm).
- Remove debris that has entered the outdoor heat exchanger.
- Remove dust and dirt from temperature sensors.
- Check the condition of the wiring and connection lines.
- Inspect hoses, pipes and their connections for leaks.
- If necessary, lubricate the corresponding points on the motor and fan.
The compressor is usually equipped with an oil heating system. Before starting the pump, leave it on for a few hours to allow the oil to warm up. Without this precaution, equipment can fail very quickly.
The heat pump air water transforms the energy of the external environment into heat that heats the interior space. That is, with the help of this device, a dwelling or building can be “heated” with ordinary air. Moreover, the air does not burn in the furnace, but simply gives up its calories to a complex unit - a heat pump, which transports this energy into the room and gives it to the heating system.
Agree, such manipulations with energies are similar to magic. But there is nothing fantastic in heat pumps of this type. And in this article we will consider the principles of operation and the device of such a unit.
The scheme of operation of an air source heat pump is copied from a refrigerator or air conditioner, namely:
- A low-calorie energy carrier (air) boils a refrigerant filled into a cyclic circuit that connects an evaporator (heat trap) to a condenser (heat emitter).
- In the condenser, the refrigerant vapors pass into a different state of aggregation (liquid) and give off energy to the heating system.
- After that, the liquid refrigerant again goes to the evaporator, where it turns into vapor. And everything starts over.
That is, the same inverse Carnot principle is used in the work, but the main part of the installation is not an evaporator that accumulates heat from the surrounding space, but a condenser that gives the accumulated calories to the consumer.
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At the same time, the cyclical operation of the unit is provided by a special compressor, which not only pumps the refrigerant along the circuit, but also compresses it, thereby increasing the heat transfer on the condenser. However, this is not the only power unit of the installation - the heat pump is equipped with a sufficiently powerful fan that blows over the evaporator.
Well, as a heat consumer, either a convector warms up the air inside the room, or a “warm floor” system or other radiators with a large area.
But with standard batteries, thermal fans do not work very efficiently.
Moreover, the convector with a condenser is mounted indoors, and the evaporator with a fan is either outside, on the facade, or in the inside of the exhaust branch of the ventilation system.
Advantages and disadvantages of air source heat pumps
Reviews about the air-to-water heat pump are both good and bad. After all, this device, with all its undeniable advantages, is not without some drawbacks.
Moreover, the advantages include the following facts:
- Firstly, such a unit is easy to mount. Indeed, for the primary circuit, closed to the evaporator, neither earthworks nor reservoirs are needed.
- Secondly, the air eats everywhere, but the land, in personal ownership, is only outside the city, but there are even more problems with artificial or natural reservoirs. Therefore, air source heat pumps for heating can be installed even in urban areas without asking permission from the regulatory authorities.
- Thirdly, the air pump can be combined with the ventilation system, using the power of the unit to increase the efficiency of air exchange in the room.
In addition, such a pump operates almost silently and is easy to program.
Well, the inevitable disadvantages can be represented as such a list:
- The efficiency of the unit depends on the ambient temperature. Therefore, the efficiency of the device in summer is higher than in winter.
- The air pump can only be turned on in relatively light frosts. Moreover, at -7 degrees Celsius, a household air pump will no longer work. Although industrial units are switched on at -25 degrees Celsius.
In addition, an air pump is not a completely autonomous power plant. The unit consumes electricity, transforming 1 kWh into 11-14 MJ.
DIY air source heat pump: assembly diagram
Unlike rather complex geothermal and hydrothermal systems, an air-to-water heat pump is available for manufacturing even on your own.
Moreover, for the manufacture of an air system, we need a relatively cheap set consisting of the following parts and assemblies:
- Split system compressor - it can be purchased at a service center or repair shop
- 100-liter stainless steel tank - it can be removed from any old washing machine
- A polymer container with a wide mouth - an ordinary can or polypropylene is suitable.
- Copper pipes with a throughput diameter of more than 1 mm. They will have to be bought, but this is the only expensive purchase in the entire project.
- A set of shut-off and control valves, which will include a drain valve, an air etching valve, a safety valve.
- Fasteners - brackets, clips for pipes, clamps and other things.
In addition, we need the cheapest refrigerant - freon and at least the simplest control unit, without which the use of heat pumps will be very difficult, due to the need to synchronize the operation of the compressor with the temperature on the surface of the evaporator and condenser.
Assembly of the unit
Well, the build process itself is as follows:
- We make a coil from a copper pipe, the dimensions of which must correspond to the cross section and height of the steel tank.
- We mount the coil in the tank, leaving the outlets of the copper pipe outside. Next, we seal the tank and equip it with an inlet (bottom) and outlet (top) fitting. As a result, the first element of the system is obtained - a condenser - with ready-made taps for a straight heating pipe (upper fitting) and a return pipe (lower fitting)
- We mount the compressor on the wall (using the bracket). We connect the pressure fitting of the compressor with the upper outlet of the copper pipe.
- We make a second coil from a copper pipe, the dimensions of which coincide with the cross section and height of the polymer can.
- We mount the coil in a can by installing a fan at its end that blows air onto the coil. Moreover, two issues should come out of the can. As a result, this whole structure, which is the evaporator of the system, is mounted on the facade or in the ventilation shaft.
- We connect the lower outlet of the tank (condenser) with the lower outlet of the can (evaporator) by inserting a control throttle into this pipeline.
- We connect the upper outlet of the can with the suction pipe of the compressor.
That's basically it. Using the principle of operation of an air source heat pump, the system is almost ready. It remains only to fill the refrigerant into the compressor and connect the throttle valve to the control unit.
Air heating with a heat pump: calculation of the installation capacity
The power of a heat pump depends on many factors, namely: the volume of refrigerant, the surface area of the coils in the evaporator and condenser, the expected volume of heat transfer to the heating system, and so on. Therefore, in most cases, the calculation of power is carried out in special programs that take into account other input data.
In a simplified form, these programs are designed as online "calculators", with open fields for entering the following parameters:
- The area of the room and the height of the ceilings - they are used to calculate the volume.
- The region where the building is located - using this parameter, the average annual air temperature is determined, which affects the performance of the evaporator.
- The degree of insulation of the task - using this parameter, the expected "caloric content" of the heating system is determined.
At the final stage, the last two parameters are converted into coefficients by which the volume of the room is multiplied. The figure obtained as a result of such manipulations is compared with tabular values that link the pump power with the heated volume.
As a result, it turns out that heating a house with an area of 100 square meters, as a rule, requires a 5-kilowatt heat pump, and a dwelling for 350 square meters can be heated with a 28 kW pump.
Air source heat pump: the nuances of unit maintenance
The air-to-water heat pump does not require any special maintenance, with partial disassembly/assembly.
To maintain the system's performance, the owner will only have to perform the following manipulations:
- Periodic cleaning of the fan and grill on the evaporator from clogged debris (leaves, dust, and so on).
- Periodic lubrication of the compressor, performed according to the scheme provided by the manufacturer.
- Oil change in power units (compressor, fan).
- Periodically check the integrity of the copper refrigerant piping and power cable that feeds the compressor and fan.
Installation of an air-to-air heat pump, unlike ground and water, does not require laying pipes and drilling wells. It is simpler and much cheaper, but has its own characteristics.
An incorrectly installed and connected air source heat pump may not operate efficiently. Its conversion factor will decrease, which will affect the payback period.
Types of air-to-air heat pumps
There are two types of heat pumps of this class - monoblock and separate. As a rule, monoblocks have a small power, up to 2 kW of electricity consumed. In a separate version, the HP power can reach up to 10 kW, although this is rare and such heat pumps are usually made to order.
In a monoblock, all equipment (condenser, evaporator, compressor, etc.) is assembled in one housing. Usually they have a controller (control panel), but sometimes it can be taken out or supplied separately.
The second type of air heat pumps is separate. They have a main unit (see photo) and an outdoor unit. The outdoor unit has an evaporator and compressor, while the indoor unit has a condenser. They are connected to each other by a line in which the refrigerant circulates.
Installation of a monoblock heat pump
This equipment has a small noise level due to low power. Installation of such an air source heat pump comes down to its installation, connection of air ducts and power supply.
When choosing a place, it is worth remembering that the further the blocks are spaced, the greater the heat loss will be. Specialists say that between them there should be no more than 5 meters of the track, but often this cannot be realized (see photo). Especially when it comes to providing heat to a large house. The tubes must be insulated, and not with improvised means, but with special thermal insulation, preferably with a metallized coating.
Today, a water-to-air heat pump is a very useful and convenient means of heating your home. With the help of outside air, even if it is cold, it can heat the room without any problems.
There are several types of such equipment, which in most cases are intended for use in private homes. But we will also look at a pump that is very easy and possible to install in office and residential areas where there is not enough space to accommodate equipment.
Air-to-water heat pump
In order to be able to use the energy that surrounds us everywhere, they came up with such a unit as a heat pump. They work according to a system called the inverse Carnot principle. Also, according to this principle, the operation of air conditioners and refrigeration units is carried out.
The principle of operation of the pump is as follows: the air from the outside enters through the fan, which is located on the street. Then it goes to the next part - the evaporator. There is a substance that is necessary to heat the air. Freon gas is usually used.
It is also common in refrigeration equipment. This substance, the refrigerant, is located inside a serpentine copper tube at the bottom of the evaporator. During the heating process, the refrigerant evaporates and enters the next part of the installation - the condenser. In the same place, the substance passes from the gaseous state to the liquid, during which a lot of heat is released, which contributes to the heating of the room.
Such a process occurs constantly in a circle and due to the circulation of freon, the air in your home is constantly processed.
Heating with air-to-water heat pump
The fan can be placed either on the wall of the house, or on the territory adjacent to the house. But it should be borne in mind that there should be excellent air circulation in any case.
It is not recommended to use such a pump if you have ordinary radiators in your house. They are best combined with an air system or with a "warm floor" system. At the same time, it will help you save money, since you will spend less on heating with a traditional system.
Heat pumps air water reviews and benefits
The unit has many advantages, among them are the following:
- heating of the air in the room occurs at any time and at any temperature, even if it is negative. At the same time, there is no need to spend additional money on fuel, since air is an affordable and free medium.
- This type of pump is easy to install. You can make such a system with your own hands without any problems. At the same time, you do not need to spend a lot of effort drilling, concreting or making trenches.
- significant savings on the equipment itself. You can make a pump by spending much less money on it than if you buy another similar type of such a system in a store.
- Ease and noiselessness of work of installation.
- Possibility of automatic control of the system.
The air-to-water pump is very convenient because here you do not need to install pipes through which air could move. You only need to install the fan, having previously closed its blades with a grate.
But when choosing such equipment, some disadvantages must also be taken into account: it is best to use such a system in places where winter is not very severe, because at sub-zero temperatures (below 6-7 degrees), the pump may fail. Electricity is also required to ensure the operation of such a pump. But even compared to spending on electricity, you will save much more than using gas or other types of electric heaters.
DIY heat pump air water
Now let's see how you can assemble the pump yourself.
It is usually quite difficult to make a compressor yourself, so you need to take it ready. If buying it in a store is too expensive for you, then you can use the compressor that is on the split system. This pump has excellent performance, the best fit for our installation. We will also need two large tanks: one plastic and the other metal. And you will also need to make two serpentine structures from a copper pipe. The refrigerant will move through them.
You can make them a spiral by winding them on a cylindrical object. You will place one coil in the condenser (steel tank), and the second in the evaporator - respectively, in a plastic barrel. Well, in addition, additional details will be needed: a drain valve, adapters and brackets, refrigerant and electrodes.
When doing this, also note that when connecting the device, a large current is needed.
After installing the coils, you need to weld the steel tank and connect the components into a common system. In order to run freon into a copper pipe and at the same time check the operability of the structure, you need to use the services of a refrigeration master.
Before you put the pump into operation, it is worth determining how much power you need. To eliminate additional expenses, you should not make the pump more powerful than you need.
To do this, you can use the services of specialists who own special programs for calculating power, or you can calculate it yourself - on special sites.
It is also premature to take care of the insulation of your home, because the air temperature in the house in winter will depend on this. And the savings on heating means will also depend.
Mitsubishi Heavy Industries introduces modern technology in many areas, and offers the most complete solutions to create an environmentally friendly society.
The air-to-water heat pump is one of our products that embodies unrivaled technology to ensure minimum energy consumption, safe and reliable operation.
The air-to-water heat pump is a revolutionary energy recycling system that reduces the burden on the environment by reusing the heat generated in everyday life.
Reducing running costs with a heat pump
Heat pumps are capable of generating up to 4.44 kW of heat for every 1.00 kilowatts of electrical energy consumed, which makes this system much more efficient than all traditional methods of creating a microclimate.
How a heat pump works
An air-to-water heat pump is a system that provides heating, hot water and cooling for buildings. In general terms, the principle of operation of a heat pump during heating operation can be described as follows:
- The outdoor unit uses the refrigerant to extract heat energy from the outside air (heat source). The refrigerant enters the compressor, where, after compression, its temperature increases.
- The hot refrigerant (now in the form of gas) enters the heat exchanger of the indoor unit freon-water.
- The refrigerant transfers heat to the water, which then transfers it to the elements of the climate system.
- Coolant (back in liquid phase) is returned to the outdoor unit and the cycle is repeated.
When working for cooling, the same process occurs in reverse order - the refrigerant takes heat from the water, transfers it to the outdoor unit, and then to the air. The indoor unit determines when to turn on the outdoor unit based on the data received from the temperature sensor. If more heat is needed than the outdoor unit can supply, the indoor unit will turn on the auxiliary electric heater or other connected heating device.
Advantages
Low operating costs due to compressor inverter control. The compressor speed is controlled according to the heat/cold demand. In heating operation, the system has the industry's highest COP ratio of 4.08~4.44*
- By combining the hot water tank with the water heat exchanger of the indoor unit, it was possible to obtain a compact unit size - the base is 600x650 mm. Wiring diagrams and freon pipelines have been simplified with a change in the design of the indoor unit.
- The maximum supply water temperature is 65°C, provided that an additional heater of sufficient capacity is used so that the system can compensate for irregular and excessive hot water consumption (when using only the compressor, the maximum water temperature is 58°C).
- Various disinfection temperature settings according to country specific requirements.
- Sufficient water pressure and quality are maintained by direct water supply rather than using water from a tank, which also reduces the risk of legionella bacteria.
- Can be connected to external heat sources, including solar collectors. For more information, see the installation manual.