HOW AN AIR SOURCE HEAT PUMP WORKS

An air source heat pump (ASHP) is a renewable energy system that extracts heat from the outside air and transfers it indoors to provide heating, hot water, and, in some cases, cooling. In the UK, ASHPs are becoming increasingly popular as a sustainable and efficient way to heat homes and buildings. Here's how an air source heat pump works:

 Basic Components

1. Outdoor Unit: Contains the evaporator coil and a fan to draw air over the coil.

2. Indoor Unit: Houses the condenser coil, expansion valve, and other components needed to distribute heat.

3. Refrigerant: A special fluid that circulates through the system, absorbing and releasing heat as it changes state between liquid and gas.

4. Compressor: Increases the pressure and temperature of the refrigerant.

5. Expansion Valve: Reduces the pressure of the refrigerant, allowing it to cool down.

 How It Works

1. Absorption of Heat:

The fan in the outdoor unit draws in outside air over the evaporator coil.

The refrigerant inside the evaporator coil absorbs heat from the air, causing it to evaporate and turn into a gas.

2. Compression:

The gaseous refrigerant is then compressed by the compressor, increasing its temperature significantly.

3. Heat Transfer:

The hot, high-pressure refrigerant gas flows to the condenser coil in the indoor unit.

Inside the condenser coil, the refrigerant releases its heat, which is then transferred to the Indoor air or to a hot water system via a heat exchanger.

As the refrigerant releases heat, it condenses back into a liquid.

4. Expansion:

The liquid refrigerant passes through an expansion valve, which reduces its pressure and temperature.

The cooled refrigerant returns to the evaporator coil in the outdoor unit, and the cycle repeats.

Efficiency

Coefficient of Performance (COP): ASHPs are highly efficient, with a typical COP of 3 to 4. This means that for every unit of electricity consumed, the pump can produce 3 to 4 units of heat.

Year-Round Operation: ASHPs can operate in temperatures as low as -15°C, making them suitable for the UK's mild climate. However, their efficiency decreases at lower temperatures.

Benefits

1. Environmental Impact:  ASHPs reduce greenhouse gas emissions compared to traditional fossil fuel heating systems.

2. Energy Savings: Lower operational costs due to higher efficiency.

3. Renewable Heat Incentive (RHI):In the UK, homeowners can receive payments for the heat generated by their ASHP through the RHI scheme.

Considerations

1. Installation Cost: Higher initial cost compared to conventional heating systems, but potential savings over time.

2. Noise: Outdoor units can produce noise, so placement should be considered.

3. Efficiency in Extreme Cold: Supplemental heating might be needed during extremely cold weather.

Overall, air source heat pumps offer a sustainable and efficient heating solution, particularly suitable for the UK's climate.