20 August 2024
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Image: Charlie Mowbray, Senior Product Manager at Ideal Heating – Commercial
Charlie Mowbray, Senior Product Manager at Ideal Heating – Commercial, sheds some much-needed light on five of the most frequently misunderstood aspects of natural refrigerants.
“Heat pumps are a widely suitable and cost-effective solution for decarbonising the UK’s buildings and are vital to delivering Net Zero” states the UK government in its ‘Heat Pump Investment Roadmap - Leading the way to net zero’ published in April 2023. That’s because heat pumps reduce the reliance on fossil fuels, produce zero local carbon emissions, and can be up to 400% more efficient than traditional boilers. Heat pumps utilise the free energy in the air to heat water, even when that air temperature is as low as -20°C. When heat pumps are partnered with a renewable electricity supplier, heat generation is 100% carbon neutral.
The role of refrigerants within heat pumps
All heat pumps require a refrigerant, a bit like a fridge, but in reverse. In a heat pump, a fan passes ambient air over extremely cold liquid refrigerant. The refrigerant captures the heat from the ambient air and becomes a warm vapour. That warm refrigerant vapour passes through a compressor which produces hot refrigerant and usable heat. The heat in the hot refrigerant is then transferred to the heating and hot water system through a heat exchanger. After the heat is transferred the refrigerant passes through an expansion valve which reduces its temperature, making it cold again and enabling it to capture heat from the ambient air, continuing the cycle. It’s a neat solution and one that has been used successfully for many decades, only not until relatively recently in the UK.
The move to natural refrigerants
With heat pump technology being over 150 years old, there has understandably been a variety of different refrigerants used over the years. In the past three decades, the most popular have been R407c, R22, R410a and R32. But, as we have become more aware of the negative environmental impacts of many of these older refrigerants, the industry is moving to natural refrigerants in the form of R290 (Propane) and R744 (CO2). These are refrigerants that occur naturally, as opposed to those that are synthetically made. At Ideal Heating Commercial, we have recently expanded our own ECOMOD commercial heat pump range to include natural refrigerants. But with any change comes apprehension, and the word ‘natural’ has left many people assuming these refrigerants will not be as effective as their synthetic counterparts, which is far from the truth. That’s just one of the misconceptions surrounding natural refrigerant-based heat pumps, but there are plenty more! Let’s look at five of the most frequently misunderstood aspects of natural refrigerants and shed some much-needed light.
1. Performance
Contrary to what you might think, natural refrigerants can perform better than synthetic alternatives in heat pumps for two key reasons. Firstly, they can achieve a higher coefficient of performance (COP), making them more efficient. COP is the ratio of heat produced, relative to each unit of electricity consumed in the heat pump. Secondly, natural refrigerants can produce higher temperatures, making these heat pumps ideal for heating water. Our ECOMOD 290HT, for example, can achieve a maximum flow temperature up to 75°C. That said, designing a heating circuit to 55°C would make the system much more efficient, in line with the most recently published Building Regulations Part L.
2. Environment
Refrigerants are allocated a Global Warming Potential (GWP); those with a high GWP are extremely potent greenhouse gases that warm the planet. Older, synthetic refrigerants nearly all have a high GWP, and we expect them to eventually be phased out. R410a, for example, has a whopping GWP of 2088. Compare that to R290 at 3 and CO2 at just 1 and you can see why natural refrigerants are the environmentally friendly option.
3.Total cost of ownership
Moving to natural refrigerants is not only good for the planet, but also makes commercial sense now and in the future. As far as the present day is concerned, synthetic refrigerants are already more expensive than natural ones as the manufacturing process is more complex, and they are subject to the F-gas phase down. As their production declines, high GWP refrigerants will become increasingly scarce and therefore more expensive. Furthermore, over the life of the heat pump, if you opt for a high GWP refrigerant heat pump now, you may find yourself in the costly and inconvenient position of having a potential stranded asset in the not-too-distant future.
4. System design
Controls If you can design a heat pump system which utilises a synthetic refrigerant, then you will have no trouble in doing the same with most natural refrigerant heat pumps. The system design for R290 in particular is straightforward. In fact, a natural refrigerant heat pump system often requires less amendment to the hot water cylinder, as they do not require immersion heaters for anti-Legionella cycles due to the higher temperatures that are achievable.
5. Training
As with all refrigerants and heat pump installations, appropriate training is required. If you have already undertaken heat pump training, then the good news is that no additional training is necessary for fitting R290 heat pumps (although product specific training is always highly beneficial). However, heat pumps that use CO2 have a higher Delta T return temperature, so the system design differs slightly. Whatever training you undertake, be sure that it includes both theory and practical, hands-on training. Ideal Heating provides commercial heat pump training free of charge via our Expert Academy training team. We also strongly urge heating engineers to consider British Plumbing Employers Council (BPEC)1 accredited training on heat pumps, which is recognised as a demonstration of competence for the Microgeneration Certification Scheme (MCS)2. It provides the foundation knowledge required to correctly install heat pumps in line with industry best practice and guidelines. Natural refrigerant heat pumps are undoubtedly the way forward when it comes to commercial heating and hot water. They tick all the boxes, sometimes outperforming synthetic refrigerants, with their low GWP, getting us one step forward to that important net zero goal.
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