HOW DOES AN AIR SOURCE HEAT PUMP WORK?

An air source heat pump (ASHP) system is a highly efficient heating and cooling solution that transfers heat between the outside air and your home. In the UK, these systems are gaining popularity due to their ability to provide renewable heating and cooling while offering a significantly lower environmental impact compared to traditional gas boilers. Here’s a more detailed explanation of how an air source heat pump works:

1. Heat Absorption from the Air

The system begins by extracting heat from the outside air, even in colder temperatures. The heat pump contains a refrigerant fluid designed to evaporate at low temperatures. The outdoor unit uses a fan to draw in the air, which then passes over the heat pump’s evaporator coil. The refrigerant inside the coil absorbs heat from the air, causing it to evaporate and turn into a gas.

2. Compression of the Refrigerant Gas

Once the refrigerant has absorbed heat, it becomes a low-pressure gas. This gas is then compressed by the heat pump’s compressor. The compression significantly increases the gas's temperature, concentrating the thermal energy. This step is crucial because it enables the heat pump to continue providing heating even on colder days, as the heat is intensified and can be transferred efficiently into your home.

3. Heat Transfer to the Building

The high-temperature, high-pressure refrigerant gas is then passed through a coil or heat exchanger inside the heat pump. Here, it transfers its heat to the building's heating system, typically water circulating through underfloor heating or radiators. As the refrigerant cools, it condenses back into a liquid.

4. Expansion and Cycle Repeats

The refrigerant liquid is then expanded through an expansion valve, which causes its pressure to drop and its temperature to cool further. The refrigerant then flows back to the outdoor unit to absorb more heat from the air, repeating the cycle. This continuous loop allows the system to efficiently transfer heat into the home.

5. Heating and Cooling Modes

• Heating: During winter, the air source heat pump extracts heat from the cold outdoor air and uses it to warm the home.

• Cooling: In summer, the system can reverse the flow of refrigerant. By extracting heat from the indoor air, it releases it outside, functioning like an air conditioner.

Key Features and Benefits:

• Efficiency: Air source heat pumps are highly efficient, typically generating 3-4 units of heat for every unit of electricity used to power the compressor. This translates to 300-400% efficiency.

• Renewable Energy: By extracting heat from the air, a renewable source, air source heat pumps are an environmentally friendly alternative to traditional fossil fuel heating systems.

• Reduced Carbon Emissions: By reducing reliance on gas or oil for heating, these systems help lower your home’s carbon footprint.

• Government Incentives: In the UK, there are government schemes like the Renewable Heat Incentive (RHI) that provide financial support to help with the cost of installing air source heat pumps.

Conclusion

In summary, an air source heat pump works by extracting heat from the outdoor air, compressing it to increase its temperature, and then transferring this heat to your home. With its energy efficiency, environmental benefits, and ability to provide both heating and cooling, the air source heat pump is an increasingly popular choice for sustainable home heating in the UK.