Differences Among Air Source Heat Pumps Operating at High, Medium, and Low Temperatures, and Guidelines for Selecting the Appropriate One

In the realm of sustainable home heating, heat pumps have emerged as a popular choice. These ingenious devices harness the ambient heat from the air or ground to warm homes, providing an eco-friendly alternative to traditional heating methods.

One significant development in heat pump technology is the adaptation of modern compressors for a second cycle, resulting in medium temperature heat pumps. These units can deliver temperatures suitable for both hot water and central heating, marking a step forward in comfort and efficiency.

For those with ample land, ground source heat pumps are an option. Living near water bodies opens up the possibility of water source heat pumps. However, it's essential to note that these heat pumps cannot deliver different temperatures for hot water and central heating simultaneously.

When it comes to controls, a balance must be struck. Simplistic controls may not provide efficient performance, while complex controls can be challenging to manage. Understanding the manufacturer's jargon is crucial when dealing with heat pump controls.

The refrigerant used in heat pumps also plays a crucial role. R32 is now commonly used in new air source heat pumps, offering flow temperatures up to around 60°C to 65°C. Low temperature air source heat pumps, the first available, have a maximum flow temperature of around 55°C.

However, due to their high global warming potential, refrigerants like R410a, which was previously used in low temperature heat pumps, are being phased out. The latest medium- and high-temperature air source heat pumps are now using natural refrigerants such as R290 (propane) and R744 (CO2) instead. These refrigerants have a low Global Warming Potential (GWP under 150), making them more environmentally friendly.

High temperature heat pumps can reach higher temperatures, facilitating their use in existing buildings with traditional radiators. These models often use two different refrigerants and compressor systems to achieve higher temperatures. R744, a refrigerant used in high temperature heat pumps, can achieve high temperatures due to its ability to be compressed to extremely high pressures.

On the other hand, R290 is becoming the go-to refrigerant for air source heat pumps due to its lower global warming potential. However, it is highly flammable, so it's crucial to use controls efficiently to maintain efficiency and safety.

Lastly, it's important to remember that the heat pump's efficiency is influenced by the controls and software, which can affect its ability to match the home's heat load. Efficient controls can help ensure that the heat pump operates at its best, providing comfortable warmth while minimising energy consumption.