In the heat source system, the absorbed environmental heat flows to the evaporator. There it encounters the liquid refrigerant. This refrigerant evaporates even at very low temperatures. This allows the heat pump to absorb heat from the environment even in frosty conditions. The refrigerant absorbs heat from the environment and becomes gaseous.
¿Cómo funciona una bomba de calor?
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¿Cómo funciona una bomba de calor?
Una bomba de calor de aerotermia funciona transfiriendo el calor del aire exterior a un espacio interior, mediante intercambio térmico. La unidad exterior de la bomba de calor, posee un ventilador que impulsa un caudal de aire del exterior a través de una batería de intercambio denominada comúnmente como evaporador.
Important facts at a glance:
- A heat pump extracts up to three quarters of the energy it needs from the environment (air, ground, or water) and only one quarter from electricity.
- The core components are the evaporator, compressor, condenser, and expansion valve, which work together in a closed circuit.
- Heat pumps function reliably even at very low outdoor temperatures and can be used to cool rooms in addition to heating them.
Structure and operating principle of the heat pump
Regardless of the tapped environmental energy source, the heat pump system consists of three parts:
Heat source system: extracts energy from the environment
Heat pump: Makes environmental heat usable
Heat distribution and storage system: distributes and stores heat in the building
Proceso del ciclo de refrigeración: el núcleo del principio de la bomba de calor
Independientemente de la fuente de calor que se utilice para generar calor, el proceso del ciclo de refrigeración, que consta de cuatro pasos, siempre forma parte del modo de funcionamiento de la bomba de calor.
The refrigerant, now in gaseous form, enters the compressor. This requires electricity and greatly increases the pressure of the gas. The increase in pressure also raises the temperature of the gas to the level required for heating. The compressor is the central component that uses electrical energy to convert environmental heat into usable heating energy.
Interesting fact: This principle can be observed not only in the functioning of heat pumps. If the opening of a bicycle pump is closed and the air is compressed, the cylinder of the air pump heats up.
The hot, gaseous refrigerant flows into the condenser. There, it releases heat to the heating system by warming the heating water. During this process, the gas cools down and becomes liquid again. The released heat energy is then distributed to the rooms via the heating distribution system (e.g., underfloor heating). Some of it can also be stored in a buffer or hot water tank for later use.
The refrigerant, which is now liquid again but still under pressure, is passed through an expansion valve (also known as a pressure relief valve). This causes the pressure to drop significantly, the refrigerant cools further, and the entire heat pump process begins again.
A continuación, un segundo intercambiador de calor (condensador) transfiere la energía del vapor calentado al circuito de calefacción (suelo radiante, radiadores, depósito de calefacción y/o acumulador de ACS). En el proceso, el refrigerante, que todavía está bajo presión, se enfría y se licúa de nuevo. Al pasar a través de la válvula de expansión disminuiremos la presión del refrigerante, y una vez que ha alcanzado su estado inicial, el ciclo de refrigeración vuelve a empezar de nuevo.
Explicado de forma sencilla: La bomba de calor
Principio de funcionamiento de la bomba de calor aerotérmica
Una bomba de calor aerotérmica puede constar de una unidad interior y una unidad exterior o sólo de la unidad exterior. En ambos casos, un ventilador provoca el paso del aire exterior por un intercambiador de calor (bateria de evaporación). Por el intercambiador circula el refrigerante que cambia de estado físico a temperaturas muy bajas. Al entrar en contacto con el aire exterior, el refrigerante se calienta y se convierte gradualmente en vapor. Para aumentar el calor resultante hasta la temperatura requerida se utiliza un compresor. Éste comprime el vapor y aumenta tanto la presión como la temperatura del vapor refrigerante.
Repetición continua del proceso
Estos procesos tienen lugar en un circuito cerrado (circuito frigorífico) dentro de la bomba de calor. Para transportar el calor, se utiliza un líquido (gas refrigerante) que tiene la capacidad de evaporarse a temperaturas muy bajas. Incluso temperaturas de -20º C son suficientes para proporcionar energía y evaporar el gas. A continuación, el refrigerante en forma de vapor frío, por ejemplo a -20º C, se comprime en el compresor. Este proceso aumenta la presión y hace que aumente considerablemente su temperatura. Este refrigerante en forma de vapor caliente se condensa y libera toda la energía en forma de calor al sistema de calefacción en el condensador (intercambiador de placas). Posteriormente, la presión del refrigerante líquido se reduce considerablemente al pasar a través de la válvula de expansión. Esto hace que la temperatura del líquido vuelva a descender al nivel inicial. El proceso vuelve a comenzar desde el principio.
Refrigerant: Essential for the heat pump to function
A special refrigerant is essential for a heat pump to function. A key feature is its extremely low boiling point. This allows the liquid to turn into a gas even at very low temperatures – sometimes as low as minus 20 °C. This is why a heat pump works reliably even in winter when outside temperatures are low.
Incidentally, the latest generation of Viessmann heat pumps use the natural refrigerant propane (R290), which is in no way inferior to conventional refrigerants in terms of its properties.
La compresión requiere corriente eléctrica
Un componente esencial del circuito de refrigeración es el compresor. Esto se debe a que, sin compresión, las temperaturas de salida son demasiado bajas para poder calentar un edificio a una temperatura confortable, más aún en días muy fríos con temperaturas bajo cero.
Heat pump for heating and cooling
The heat pump functions reliably even at very low outdoor temperatures. Water-to-water and brine-to-water heat pumps are particularly efficient at supplying heat, as the ground and groundwater maintain constant temperatures throughout the year. However, air-to-water heat pumps also operate at temperatures below freezing. Viessmann heat pumps, such as the Vitocal 250-A, remain reliable even at low outdoor temperatures (below -10 °C).
Thanks to their reversible function, heat pumps can also cool in summer
The operating principle of a heat pump is reversible. This means that rooms can not only be heated, but also cooled with a heat pump, provided that the technical requirements are met. There are two different cooling methods:
- Natural cooling: The heat pump remains switched off. The cooler temperature of the environmental heat source (ground, groundwater) is used to cool the rooms via a heat exchanger.
- Active cooling: The function of the heat pump is actively reversed so that the heat is transported from the rooms to the outside. This mode of operation is similar to that of a refrigerator.
You can read about the detailed process of the cooling functions in our guide to natural and active cooling.
Reversing the function of the heat pump for cooling
The principle of operation of the heat pump is reversible. For this reason, rooms can not only be heated, but also cooled - if the technical requirements are met. A distinction must be made between Natural and Active Cooling. While in the latter the function of the heat pump is actively reversed, it remains switched off in passive or natural cooling.
FAQ – Frequently asked questions about how heat pumps work
The power consumption of a heat pump depends, among other things, on its efficiency (annual performance factor) and the required heating capacity. Most of the heating energy comes from the environment; the electricity is mainly needed to operate the compressor.
Yes, most modern heat pumps can generate hot water for the household in addition to heating rooms. There are also standalone hot water heat pumps specifically designed for hot water production, which efficiently heat drinking water all year round. These can either use exhaust air from the house (e.g., from the basement or laundry room) or extract heat from the outside air. You can find out more about this special type of heat pump in our guide to hot water heat pumps.
Yes, Viessmann offers heat pumps that reach high flow temperatures (e.g., 70 °C) and can therefore also be used in well-insulated existing buildings with conventional radiators.
You can read more about this in our guide to heat pumps in older buildings.
The combination of a heat pump and a PV system is ideal. The solar power generated during the day can be used directly to operate the heat pump, which further reduces operating costs and increases independence.
A geothermal heat pump uses the heat stored in the ground. There are two main methods used for this:
- Ground probes: These are drilled vertically up to 100 meters deep into the ground. They require little space and are particularly efficient.
- Ground collectors: These are laid horizontally and over a large area at a shallow depth. They are cheaper to install but require a larger garden area.
The most suitable method depends on the conditions of your property. You can find more details in our guides to ground collectors and geothermal probes.
En la práctica, se utilizan varios compresores, como los de pistón o los scroll, todos ellos de accionamiento eléctrico. El consumo de energía para la compresión depende de muchos factores. Entre ellos, la demanda de calor, la tecnología del compresor y, no menos importante, la diferencia de temperatura entre la fuente de calor y el sistema de calefacción. Por regla general: Cuanto mayor sea la diferencia de temperatura entre la fuente de calor y la temperatura de impulsión, más tendrá que trabajar el compresor.
