Skip to main content

Why CO2 (R744) Heat Pumps Are The Best For Domestic Hot Water

At Clade we’re almost evangelical about the benefits of using CO2 as a refrigerant in heat pumps – it’s environmentally friendly, safe, and performs extremely well.

Previously, we’ve mostly discussed their use for space heating. Today we wanted to deal specifically with why CO2 heat pumps work so well for heating domestic hot water. .

How CO2 Heat Pumps Perform Well For Hot Water

One of the common misconceptions about heat pumps, frequently repeated in the newspapers, is that they can’t reliably heat water above around 60 degrees C.

That’s just not true. CO2 heat pumps have proven again and again that, even with variable ambient conditions, they can produce a hot water supply at 80 degrees C. 

At Clade we have delivered CO2 heat pumps that have delivered consistent, sanitary hot water for leisure centres, schools and healthcare institutions. Traditionally these applications would have used gas boilers or combined heat and power but, with the pressing need to decarbonise, they are looking for low carbon alternatives.

Our CO2 heat pumps can produce flow temperatures of up to 80 degrees C, which is more than enough for most hot water requirements. They can do this while maintaining a large delta temperature and low coefficient of performance (COP) of over 4. All this while using CO2 as a refrigerant, which has a global warming potential (GWP) of just 1.

That means they’re not only low carbon, safe and future-proof but they perform extremely well. There is no sacrifice of performance in order to decarbonise. 

The Best CO2 Heat Pump Configuration For Hot Water

The key to ensuring your CO2 heat pump delivers high performance is, first and foremost, to use good engineering practice in the design and install. 

Hot water is ideal for CO2 because the return temperature to the gas cooler (condenser in a conventional heat pump) can always be kept low. A plate heat exchanger should be used to “load” a domestic hot water store rather than a coil as you would see in a calorifier. As a hot water store gets near to full, or as a result of convection currents, the temperature around the coil rises and so therefore does the return to the heat pump. Whereas with a loading plate heat exchanger the process is more controlled and happens outside of the store, maintaining the desired return temperature. 

We have a recommended schematic on our website here.

All this is standard practice for Clade CO2 heat pump installations – we don’t just take care of the design, manufacture and install – we can help with configuration and on-going support and maintenance to ensure consistent performance.