Air Source Heat Pumps
How do they work?
An air source heat pump (ASHP) is a heating system that extracts heat from the outdoor air and transfers it indoors to provide heating for a property. It works by utilising the principles of refrigeration to absorb heat from the air and deliver it at a higher temperature suitable for heating purposes. Here's how an ASHP works for a UK homeowner looking to install a new heating system:
1. Outdoor Unit: The ASHP consists of an outdoor unit, typically installed on an external wall or ground-mounted in the vicinity of the property. This unit contains a fan and a refrigeration system.
2. Heat Absorption: The fan draws in air from the surrounding environment. Even at low temperatures, there is heat energy present in the air. The ASHP's refrigeration system contains a liquid refrigerant that absorbs this heat energy from the outdoor air.
3. Refrigerant Circulation: The absorbed heat causes the refrigerant to vaporize into a gas form. The gas is then compressed by a compressor within the outdoor unit, increasing its temperature.
4. Heat Exchange: The heated refrigerant gas passes through a heat exchanger known as the condenser. In the condenser, the hot gas releases its heat energy to a water-based central heating system or directly to the home's underfloor heating or radiators.
5. Expansion Valve: After releasing its heat, the refrigerant returns to a liquid state and passes through an expansion valve, which reduces its pressure. This prepares the refrigerant to repeat the cycle of heat absorption from the outdoor air.
6. Indoor Distribution: The heated water or air is then distributed throughout the home, providing warmth and comfort. It can be circulated through radiators, underfloor heating systems, or even air handling units, depending on the specific heating system setup.
7. Optional Hot Water: Some ASHPs can also provide domestic hot water by incorporating a separate hot water cylinder or utilising a heat pump with a built-in hot water tank. This allows homeowners to have a combined heating and hot water system.
ASHPs are an energy-efficient heating solution, particularly in moderate climates like the UK, where outdoor air temperatures seldom reach extreme lows. They can extract heat from the air even when temperatures are below freezing, though their efficiency decreases as temperatures drop. ASHPs are an attractive option for UK homeowners looking to install a new heating system as they offer reduced energy consumption, lower carbon emissions, and potential cost savings compared to traditional heating systems like gas boilers or electric heaters.
Benefits of installing an air source heat pump?
Energy efficiency
Air source heat pumps are highly efficient because they transfer heat rather than generate it directly. Energy Saving Trust states that, for every unit of electricity used, a heat pump can typically provide around three to four units of heat. Actual efficiency varies depending on factors such as the system design, outside temperature and how the heat pump is operated.
Source: Energy Saving Trust
Reduce energy bills
ASHPs can help homeowners reduce heating costs in some circumstances, depending on the heating system being replaced, the property, the system design and the energy tariff. Running costs vary from home to home.
Low maintenance
ASHPs generally require minimal maintenance. Regular inspections, filter cleaning or replacement, and occasional checks of the refrigerant levels are typically sufficient to keep the system running optimally. Additionally, ASHPs have a long lifespan, providing reliable heating for many years with proper care.
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