The principle of operation of a heat pump for heating a house

For the transformation, transfer and conversion of heat energy, a special device is used that resembles an air conditioner or refrigerator. The heat pump is not used for heating - it only transports more heat than it receives from the network. With the help of the device, you can pump the energy of the soil, air or water into heating communications.

Working principle and design

The heat pump consists of a freon circuit with a compressor, an expansion valve, heat exchangers (condenser, evaporator) and copper piping. The assemblies are tied together using fittings and automatic parts.

The principle of operation of the unit is based on the selection of low-grade heat:

• water (from +2 to +7 degrees);
• air (from -25 to +35 degrees);
• soil (from -5 to +5 degrees).

In the process of taking heat resources, the initial medium is cooled, and the refrigerant of the internal circuit begins to boil and transforms into steam. The gas is compressed by the compressor and abruptly loses volume while simultaneously increasing temperature and pressure. The action of the heated freon is to transfer heat resources to the heating main. Heat pumps operate on a closed-circuit principle, using only energy without directly heating the coolant.

The unit allows you to get 3-5 kW of heat from 1 kW of used energy resources.

Varieties of heat pumps

Heat pumps for heating a private house are classified according to several criteria. Depending on the type of power transmission:

• Compression - consist of a compressor, condenser, evaporator and expander. The equipment operates on the principle of a cycle of compression and expansion of the heat carrier with further heating.
• Absorption - operate on the basis of an absorbent and freon. The absorption device is efficient and is a new generation pump.

According to the heat source, you can select the device:

• air - extracts thermal resources from the atmosphere;
• geothermal - takes energy from water or soil;
• secondary - works with secondary heat of water or air.

Secondary heat devices can take energy from sewage.

The heat pump apparatus also differs in terms of the environment for the intake and transformation of energy, features and methods of operation.

Ground-water system

The devices allow you to receive heat from the bowels of the earth all year round. The following modifications can be selected according to the type of geothermal circuit:

• Horizontal - a system in the form of pipes located below the freezing of the soil, at a depth of 1.5-2 m. The temperature regime throughout the year reaches + 3 ... + 15 degrees, so heat can be obtained at any time.
• Vertical - the reservoir looks like a borehole 50-200 m deep. Inside there are special probes that take heat from a constant temperature gradient.

When arranging a vertical contour, the geological composition of the soil must be taken into account. On the site where the horizontal contour is located, you cannot build houses, lay tiles.

Water-to-water system

To heat the room, you will need to use the energy of groundwater with a constant temperature of +7 and above degrees. The technology provides for the supply of water by a centrifugal pump to a special station. Thermal energy is transferred to the antifreeze by the lower circuit of the device.This option is allowed on sites:

• without groundwater or with a minimum level of their occurrence;
• with wells in which the water mark does not decrease;
• with minimal salt composition and pollution;
• equipped with a drainage well, capable of receiving from 2200 liters of wastewater per hour.

The best option for water-to-water equipment is an area near a river or other body of water.

System "water-air"

Heat pumps do not heat the air inside the rooms, but the heat carrier itself. It can be used for heating, DHW preparation. The system has a number of advantages:

• installed without drilling an external contour;
• it is reliable and durable;
• effective in autumn and spring.

The disadvantages of pumps include:

• decrease in COP when the temperature reaches +1.2 degrees;
• using reverse for defrosting the outdoor unit.

Stations are not the only means of generating heat. They function in conjunction with a heating boiler.

Air-to-air system

Air-to-air devices receive heat energy from street air masses. Outwardly, they resemble air conditioners, but they can operate at low temperatures. Cold air is heated in a condenser. The advantages of TN include:

• cost comparable to the price of an air conditioner;
• quick installation;
• no risk of leakage of heat carriers.

Among the disadvantages of the systems:

• the ability to operate only at temperatures up to -20 degrees;
• the need to install a special block inside each room;
• lack of conditions for obtaining hot water.

Air-to-air heating equipment can be used to additionally heat a summer cottage or a country house.

System selection criteria

Before buying a heat pump, you need to consider:

• System setup costs. To connect a VT in Moscow, you will need to lay a horizontal contour. A pit is dug (10 thousand rubles / shift for renting an excavator), then preparation for work is carried out (5 thousand rubles). The well costs 1000 rubles / lm, taking into account the installation and piping of the probe. For the system to work normally, 350 m of the circuit or 350 thousand rubles will be needed.
• Energy consumption. A 9 kW heat pump consumes 2.7 kW / h of electricity, which is cheaper than a similar electric boiler.
• Payback. Alternative heating, taking into account installation costs and electricity consumption, will pay off after 3 years.
• Climatic conditions of the region of residence. THs are ineffective in areas with frosty winters. They will not be able to take the required amount of heat from the soil, air or water.
• Device power. The owner of a one-story house of 10x10 squares must make calculations based on: the maximum negative temperature (-20 degrees); temperature differences outside and in the room (20 - -20 = 40); heat loss of walls (brick - 13.5 kW). To the last indicator of the minimum power, you need to add about 50%.
• Storage tank capacity. With 3 starts of the pump, 30 liters of water are needed, with 5 starts - 20 liters.

When selecting equipment, the condition of the house and the features of the area where it is located are taken into account.

Advantages and disadvantages

Heating communications with a heat pump have a number of advantages:

• energy saving: at a consumption of 1 kW / h, 4 kW / h of heat is obtained;
• reducing the cost of repairing the system;
• versatility - suitable for installation in regions without gas mains, power lines, because will operate on air, soil or water;
• full automation of the system - in case of a long absence, the owner can set a constant temperature regime of +10 degrees;
• environmental safety - does not produce oxides, acids and benzoic compounds;
• no emergency situations - the coolant and system components do not heat up to critical temperatures;
• the ability to operate at temperatures up to -15 degrees;
• reversibility - the units cool the house in the summer, removing heat from the rooms and directing it to the backup environment;
• long-term use: without overhaul, the pump is used for 25-50 years, a compressor spare part fails every 15-20 years.

The disadvantages of using heat pumps include:

• financial costs for organizing a geothermal system;
• long-term (5-10 years) payback of the system;
• the need to use additional heating in cold regions.

In floor heating systems, it is allowed to use fan coils that transfer heat or cold to air from water. If you have an old home, you will need heating redevelopment.

Popular heat pump manufacturers

Heat pumps are mainly produced by companies from Asia. Daikin, Mitsubishi Electric and Hitach were the first to supply the European market. The equipment is also produced by manufacturers from South Korea (LG and Samsung), China (Midea and Gree).

European brands Dimplex, Nibe, Alpha-Inno Tec, AJ Tech, CIAT, Technibel, Atlantic, Airwell, Buderus also have ATW modifications.

DIY heat pump

It is possible to make a heat pump yourself only for heating a small house.

1. Purchase an old refrigerator and disassemble it by removing the automation.
2. Make a condenser from a 100 L steel tank cut in half. A copper coil with 1 mm thick walls is placed in the tank.
3. Make a coil by winding a copper tube around a gas or oxygen cylinder observing the same distance between the turns.
4. Fix the turns by threading the wire through the holes in the aluminum corners.
5. Weld parts of the tank.
6. Make an evaporator from a 60-80 liter plastic container. It is equipped with a coil and a thread for the drain and supply pipes.
7. Install the equipment in the room and bring 2 air ducts to it, cut into the front sash.
8. Solder copper pipes, pump in freon.
9. Make a starting start and connect the structure to the heating.

Air will be supplied through the upper channel to the freezer, cooled and supplied to the housing. After warming up by a heat exchanger on the rear wall, air masses will enter the room.

As a result of the work, a system with a closed loop is obtained. Refrigerant circulates in it, taking and transporting energy from the evaporator to the condenser. The heat energy received has a small power, therefore, it is required to additionally connect a warm floor or low-inertia type radiators.

The outlet water temperature will be no more than 50-60 degrees.

Scheme

A bivalent heating system scheme will help to save on the independent manufacture of the device and its installation. It involves calculating the power of the heat pump based on the minimum temperature. The unit will not operate at full capacity throughout the year.

Nanos in this case is a passive unit to which a gas or solid fuel boiler is connected. The bypass is connected to the latter.

Thermal pump modifications are efficient but expensive equipment. With a long payback period, they will be the only alternative in areas without gas supply.