An Introduction to heat pumps

What is a heat pump?

While based on a similar technology to air conditioners and freezers, heat pumps use the heat found in external air, water or the ground and compress it using electricity. This compression causes the extracted warmth to heat up and then be released into the conditioned space through the use of water within a wet central heating system.

The history of the heat pump

While heat pumps have been used in a number of different areas for years, the first heat pump is said to have been built in 1856 and the first ground source was 1948, it is only within the last few that popularity has soared with heat pumps being used for heating both domestic and commercial properties.

They provide heat energy from a variety of sources, depending on the model, to a heat sink. In order to work, they are required to shift thermal energy in the opposite direction to natural order. In other words, they take heat from a cooler environment and release it into a warmer one. Although classed as a renewable heating method, heat pumps tend to use around 1 unit of electricity for every 3-5 units of heat and so are not completely self-sufficient.

Seasonal performance factor

The seasonal performance factor of a heat pump is how much heat energy is generated using one unit of electricity over the course of a year. The higher the SPF, the more heat is generated for the same unit of electricity. Usually, air source heat pumps are around 3, water source heat pumps around 3.5 and ground source heat pumps around 4. The reason for the change is the difference in temperature witnessed in each heat source over the seasons. So the outside air temperature falls just when the air source heat pump needs to be providing the most heat, whereas the ground stays at much more of a constant temperature, meaning that the ground source heat pump doesn’t have to use as much electricity to reach the same temperature.

Important considerations for heat pumps

As heat pumps do not heat up water to the same extent as boilers within wet central heating systems, there are some important things to research before you install one. The first is radiator size. If you are replacing your wet central heating system with a heat pump, your current radiators may not be of an adequate size for the rooms. Secondly, as the heat is not of the same temperature as gas, oil and biomass boilers you would need to have a well-insulated house to ensure that the required temperature is reached. This is a recent/new build, an insulated solid wall property and cavity wall properties with cavity insulation.