Operation of an air heat pump

An air-source heat pump can extract heat from the ambient air even at low temperatures — down to minus 20 degrees Celsius. Even at such temperatures, the refrigerant used will evaporate.

The refrigeration cycle process as part of the operating mode

The air heat pump uses the surrounding air as a heat source to supply the entire building with heat. During operation, a built-in fan actively draws in air and directs it to the heat exchanger — the evaporator. A refrigerant circulates in it, whose physical state changes at low temperatures due to its thermal properties. When it comes into contact with the supplied “warm” outdoor air, it heats up until it eventually begins to evaporate. Since the temperature of the resulting vapor is still relatively low, the vapor flows on to an electrically driven compressor. This increases the pressure, which also raises the temperature. Once the refrigerant vapor has reached the required temperature, it flows to the next heat exchanger — the condenser — where it transfers heat to the heating system and condenses.

The heat obtained in this way can be used for space heating or domestic hot water. Before the cooled refrigerant can be reheated and compressed again, it first passes through an expansion valve. This causes the pressure and temperature to drop back to the initial level, after which the cycle can be repeated.

Air heat pump

Air heat pumps use the free energy of the ambient air for heating. They are ideal for modernization projects and can be positioned flexibly.

Heat from the air

[1] Vitocal air heat pump
[2] Hot water cylinder
[3] Heating water buffer cylinder

Heat from the air (with outdoor unit)

[1] Vitocal split air heat pump
[2] Hot water cylinder
[3] Heating water buffer cylinder
[4] Outdoor unit

Optimized components ensure economical operation

Modern Viessmann air heat pumps are characterized by very high efficiency; their coefficient of performance (COP) is up to 4.0 at an outdoor temperature of 2 °C and a flow temperature of 35 °C. COP indicates the instantaneous ratio of useful heat produced to the drive energy consumed. Such a high value can only be achieved through coordinated components. In this case, an energy-efficient high-efficiency pump, a variable-speed fan, a compressor with anti-vibration mounts and an electronic expansion valve ensure the highest possible level of efficiency. Viessmann air heat pumps are also among the quietest units available and are optimized for using self-generated energy from photovoltaic (PV) systems.

Improving life-cycle assessment with green electricity

Heating with ecological energy is considered climate-resilient. Depending on output and outdoor temperature, usually only part of the drive energy needs to be supplied as electricity. For some time now, many utilities have also been offering special heat-pump tariffs that are not only more financially attractive than standard electricity tariffs but also more ecological. By combining an efficient air heat pump with green electricity, system owners protect both their wallets and the environment.

Cooling with an air heat pump

Although the primary task of an air heat pump is heating, thanks to reversible operation it can also be used for cooling. This ensures a pleasant indoor climate in all rooms not only in the colder months but also in the warmer ones.

Author: viessmann.lv