Early forms of heat pumps were solely based underground, relying on using heat stored underground from the sun’s solar radiation. Although still an efficient and useful system, recent developments have enabled the introduction of Air Source Heat Pumps, which harvests low-level energy from outdoor air and uses this to transfer heat for the supply of hot water and heating.
Air Source Heat Pumps
Typically, an air source heat pump will provide 3kWh of heating energy for every 1kWh of electricity it uses. This provides an efficient reduction in running costs for a home. Because of the way the system works, it will provide an effective heat source even when temperatures reach as low as -20 degrees outside. The system also offers the advantage of giving off no local co2 emissions, reducing its impact on the environment.
An air source heat pump will work on the similar principle to a domestic refrigerator, working on a continuous cycle of changing a refrigerant from liquid to vapour. By pulling heat from the outside air into a refrigerant, it is then processed through a compressor and condenser, enabling it to emit heat as it condenses. After completing this, the refrigerant drops in temperature and returns to the start of the cycle.
Although more commonly associated with air conditioning systems, which will transfer heat from one environment to another, heat pumps can also then provide an effective heating solution, being recognised as a renewable heat technology.
Advantages if Air Source Heat Pumps (ASHP)
- Could lower fuel bills – compared to conventional electric heating
- Can offer a form of income through governments Renewable Heat Incentive
- Need little maintenance – simple self-contained system
- Easier to install than Ground Source Heat Pumps
- Suitable for all size of property – can be fitted in flats & terraced houses
Ground Source Heat Pumps
This more conventional form of renewable energy uses the heat from the sun’s solar radiation to supply a source of hot water and heating. Directly beneath the Earths surface, the ground maintains a relatively constant temperature of approximately 12 degrees, and during colder months, will be substantially warmer than the air & buildings above. By using a system of pipes buried in the ground, a mixture of refrigerant and water is used to absorb heat from the ground, before being concentrated and transferred to a building. This system can then provide a perfect low temperature heating system such as underfloor heating.
The efficiency and size of the system will determine how much heat can be harvested. Longer ground loops will draw more heat, although if space is limited, a vertical borehole can be used in a similar manner.
Ground Source Heat Pumps will offer the same advantages as an Air Source system, allowing you to lower your fuel costs and potentially earn money through your system. Heat pumps can have some impact on the environment as they need electricity to run, but the heat they extract is constantly renewed naturally.