How does a heat pump work?
The heat pump principle
FAQ 23.02.2022 | Karl KrollThe way a heat pump works is often compared to the reverse principle of a refrigerator. While a refrigerator extracts heat energy from its interior and transfers it to the outside, a heat pump does the opposite:
it extracts free heat energy from the environment and transfers it to the medium water,
which is then used for heating, for example in the underfloor heating system, or for generating hot water.
Let our qualified specialist partners advise you individually and without obligation about our products.
The big advantage: The heat pump does use electricity to harness environmental energy for heating and hot water. However, an air-to-water heat pump, for example, can usually draw up to 75 % of the required energy from the environment - and only needs to draw 25 % as electricity. This makes it particularly efficient compared to heat generators that use heating oil or natural gas, for example.
Where does the environmental heat come from?
Heat sourcesThe most common heat sources
The air-to-water heat pump uses environmental heat from the outside air - this even works at very low outside temperatures. Using thermal energy from the ground with a brine to water heat pump, also called a ground source heat pump, is somewhat more efficient.
But how does it work that energy is extracted from icy cold air in winter, relatively cool soil or groundwater to heat our buildings? How is it possible to generate pleasant heat without combustion and flame?
How heat generation works
Step by stepCircuit of a heat pump
A refrigerant circulates in each heat pump. Refrigerant is a medium that can absorb heat at low temperature and low pressure and that can release heat at high pressure and thus increased temperature. The change of state of the refrigerant, which is hermetically sealed inside the heat pump system, provides the necessary energy transport. In heat pumps, the refrigerant goes through the following circuit:
1. Evaporating Regardless of the energy source, the environmental energy is transferred to the refrigerant in the evaporator. The liquid refrigerant gradually evaporates, becomes gaseous, expands and absorbs energy from the environment. You can compare this to water, which turns into steam when heated, except that this happens faster with refrigerant and at sub-zero temperatures.
2. Compressing: Because the temperature of the refrigerant vapour is not sufficient to heat a room, the vapour is sucked in with the help of a refrigerant compressor driven by electricity. The compression increases the pressure and the refrigerant vapour heats up considerably. You can imagine a bicycle pump in whose piston the compressed air becomes warmer.
3. Liquefying The hot, pressurised refrigerant vapour flows into the condenser. Since the energy previously absorbed from the environment cannot be lost, it is transferred here to the connected heating system in the form of heat.
4. Relaxing: The energy release causes the refrigerant to become liquid again and the pressure to drop. It flows back to the evaporator through the expansion valve and the circuit starts again.
Incidentally, the refrigerant circuit can also be reversed to use heat pumps for cooling as well. With an appropriately equipped system, a ‘reversible’ heat pump can be used to cool the rooms to pleasant temperatures in the warmer months. Where necessary, the option of installing a heat pump should be taken into account from the very beginning in order for the system to be configured accordingly.
Heat pumps from Mitsubishi Electric
Products
Modern systems for sustainable heating
Sustainable, future-proof solutions for space heating and hot water at all times. Our high-quality heat pumps work reliably to always provide sufficient energy for heating and hot water.
Whether new construction or renovation, private applications, commercial or industrial - we have the right heat pump solution for you.
