Heat Pump: What It Is and How Many kWh It Consumes

Updated on: 06/12/2024

What is a heat pump?

A heat pump is a thermal machine that allows energy to be transferred from one environment to another, based on a reversible refrigeration cycle that achieves the perfect temperature, both in winter and summer. It acts in both directions, heating or cooling the room according to your needs. In other words, it functions as both a heating and cooling system.

Its operation is similar to that of refrigerators or air conditioning systems.

How does a heat pump work?

To understand how a heat pump works, it is essential to know its two main components: the hot source and the cold source. These two elements work together to transfer thermal energy from one place to another, depending on the need for heating or cooling.

The operation of a heat pump is based on a thermodynamic cycle. During winter, the heat pump absorbs thermal energy from the outside air and transfers it inside the space to increase the temperature. In this process, the cold source absorbs energy from the outside, while the hot source releases it inside, heating the space.

In summer, the cycle is reversed. In this case, the hot source is inside, absorbing the heat from the house, and the cold source is outside, releasing that energy.
 

What power does a heat pump need?

When choosing a heat pump, it is important to consider several factors that influence its required power. These factors include the size of your home, thermal insulation, the climate of the region, and the efficiency of the device itself.

Generally, the power of heat pumps is measured in kilowatts (kW), and you can find models ranging from 2 kW to 20 kW or more, depending on your home's heating and cooling needs.

To get an estimate of the required power for your heat pump, you can use our electric power calculator.

Types of heat pumps

Heat pumps can be classified into two types: by the type of circuit they use or by the source from which they extract thermal energy. 

By type of system or circuit:

•    Air-to-air heat pump: This type takes heat from the outside air and transfers it to the indoor air of the space. It is a common option for heating and cooling in both winter and summero.

•    Air-to-water heat pump: In this system, the heat pump extracts heat from the outside air and transfers it to a water circuit, which can then be used for central heating or hot water.

•    Water-to-water heat pump: This type of heat pump uses water from a natural source to extract and transfer heat. It is very efficient and is often used in larger installations.

By source of heat or thermal energy:

The second classification of heat pumps is based on the source from which they extract heat or thermal energy. 

Geothermal heat pump 

The geothermal heat pump extracts heat from the ground or groundwater, being more efficient than systems that depend on outside air.

It works through geothermal collectors installed in the subsoil, where a fluid absorbs the heat and transports it to the heat pump. This amplifies and transfers the heat to the building's heating system, and in summer, the process is reversed to cool the interior.

Hydrothermal heat pump

The hydrothermal heat pump is a system that uses the heat stored in bodies of water, such as rivers, lakes, or wells. 

This type of heat pump takes advantage of the thermal stability of water, which maintains a constant temperature throughout the year, and uses a circuit that extracts heat from that water. 

A refrigerant fluid circulates through a heat exchanger submerged in the water body, absorbing the heat from the aquatic environment. This fluid, heated by the water, is then compressed by the heat pump to increase its temperature and transfer the heat to the heating system. 

In summer, the hydrothermal heat pump can be reversed to act as a cooling system, extracting heat from the building's interior and releasing it into the water. 

Aerothermal heat pump 

The operation of an aerothermal heat pump is based on absorbing heat from the outside air through an evaporator. The heat absorbed by the evaporator is transferred to a refrigerant fluid, which is compressed to increase its temperature. 

This heat is then transferred to the building's heating system through a condenser. In summer, the cycle is reversed, and the heat pump extracts heat from the interior, releasing it into the outside air, acting as an air conditioning system.

How much does a heat pump consume?

The consumption of a heat pump can vary significantly depending on several factors, such as the device's characteristics, operating hours, and the electricity rate.

However, the efficiency of a heat pump is measured using the COP (Coefficient of Performance), which is the ratio between the thermal energy (kW) that the heat pump produces and the electrical energy (kW) it consumes.

Generally, a heat pump with a COP of three can generate three kW of heat for every kW of electricity consumed. This means that, to produce 12,000 kWh of heat per year, a heat pump with a COP of three will use approximately 4,000 kWh of electricity. On average, the monthly consumption of a heat pump in a home can be around 390 kWh, although this varies depending on specific heating and cooling needs, as well as the efficiency of the installed model.

It is important to consider that the consumption of a heat pump also depends on environmental conditions, the quality of the building's insulation, and the efficient use of the system. 

How to calculate the hourly consumption of a heat pump?

To know how much a heat pump consumes per hour, you can use its COP, which indicates the device's efficiency. For example, a heat pump with a COP of three produces three kW of heat for every kW of electricity consumed.

If you have a 5 kW heat pump with a COP of three, the electrical consumption per hour would be approximately 1.67 kW. This means that, to generate 5 kW of heat, the heat pump consumes 1.67 kW of electricity per hour.

However, remember that actual consumption can vary depending on the factors mentioned above.

How much does an air conditioner with a heat pump consume?

Air conditioners with heat pumps are more efficient than traditional heating systems. Generally, their power ranges between 2 and 5 kW. If we consider a 3 kW air conditioner with a Coefficient of Performance (COP) of three, it consumes around 1 kW of electricity per hour to produce 3 kW of heat. 

Which consumes more: traditional heating or a heat pump?

In a room of about 30 m², each kWh spent on a heat pump can offer between 2 and 6 kWh of heat in the home. The equipment will typically have a thermal power of 2.5 kW, and its electrical power will be around 0.5 to 0.8 kW. Therefore, for every 3 kWh of heat generated (thermal), the equipment consumes an average of 1 kWh of electrical energy.

When comparing the consumption between a heat pump and an electric radiator, the latter consumes an average of 1 kWh of electrical energy. Therefore, you could achieve significant savings by using the heat pump.